.
-as of [3 MARCH 2024]–
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*TYPES* —>
.
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“AMBER”
(think ‘mosquito trap’)
(think ‘dinosaurs’)
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-a plant with an elongated stem (‘trunk’) supporting leaves or branches-
.
(there is no precise botanical definition as to what specifically defines a “tree”)
(trees are supposedly “good for the environment”)
leaves absorb “odors”
(i’m assuming all “odors” must be “bad”)
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“mesquite”
(leguminous plant)
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“VINE”
“betel”
(a climbing plant)
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“VINE”
“GRAPE-VINE”
“WINE”
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*WIKI-LINK*
(Latin vīnea “grapevine”, “vineyard”, from vīnum “wine”)
A vine is any plant with a growth habit of trailing or scandent (that is, climbing) stems, lianas or runners.
The word vine can also refer to such stems or runners themselves, for instance, when used in wicker work.
In parts of the world, including the British Isles, the term “vine” usually applies exclusively to grapevines (Vitis),[3] while the term “climber” is used for all climbing plants.
Growth forms[edit]
Grapevine covering a chimney
Certain plants always grow as vines, while a few grow as vines only part of the time.
For instance, poison ivy and bittersweet can grow as low shrubs when support is not available, but will become vines when support is available.
A vine displays a growth form based on long stems.
This has two purposes. A vine may use rock exposures, other plants, or other supports for growth rather than investing energy in a lot of supportive tissue, enabling the plant to reach sunlight with a minimum investment of energy. This has been a highly successful growth form for plants such as kudzu and Japanese honeysuckle, both of which are invasive exotics in parts of North America. There are some tropical vines that develop skototropism, and grow away from the light, a type of negative phototropism. Growth away from light allows the vine to reach a tree trunk, which it can then climb to brighter regions.[6]
The vine growth form may also enable plants to colonize large areas quickly, even without climbing high. This is the case with periwinkle and ground ivy. It is also an adaptation to life in areas where small patches of fertile soil are adjacent to exposed areas with more sunlight but little or no soil. A vine can root in the soil but have most of its leaves in the brighter, exposed area, getting the best of both environments.
The evolution of a climbing habit has been implicated as a key innovation associated with the evolutionary success and diversification of a number of taxonomic groups of plants.[7] It has evolved independently in several plant families, using many different climbing methods,[8] such as:
twining the stem around a support (e.g., morning glories, Ipomoea species)
by way of adventitious, clinging roots (e.g., ivy, Hedera species)
with twining petioles (e.g., Clematis species)
using tendrils, which can be specialized shoots (Vitaceae), leaves (Bignoniaceae), or even inflorescences (Passiflora)
using tendrils which also produce adhesive pads at the end that attach themselves quite strongly to the support (Parthenocissus)
using thorns (e.g. climbing rose) or other hooked structures, such as hooked branches (e.g. Artabotrys hexapetalus)
The climbing fetterbush (Pieris phillyreifolia) is a woody shrub-vine which climbs without clinging roots, tendrils, or thorns. It directs its stem into a crevice in the bark of fibrous barked trees (such as bald cypress) where the stem adopts a flattened profile and grows up the tree underneath the host tree’s outer bark. The fetterbush then sends out branches that emerge near the top of the tree.[9]
Most vines are flowering plants. These may be divided into woody vines or lianas, such as wisteria, kiwifruit, and common ivy, and herbaceous (nonwoody) vines, such as morning glory.
One odd group of vining plants is the fern genus Lygodium, called climbing ferns.[10] The stem does not climb, but rather the fronds (leaves) do. The fronds unroll from the tip, and theoretically never stop growing; they can form thickets as they unroll over other plants, rockfaces, and fences.
Twining vines[edit]
A twining vine, also known as a bine, is one that climbs by its shoots growing in a helix, in contrast to vines that climb using tendrils or suckers. Many bines have rough stems or downward-pointing bristles to aid their grip. Hops (used in flavoring beer) are a commercially important example of a bine.[13][14]
The direction of rotation of the shoot tip during climbing is autonomous and does not (as sometimes imagined) derive from the shoot’s following the sun around the sky – the direction of twist does not therefore depend upon which side of the equator the plant is growing on.
This is shown by the fact that some bines always twine clockwise, including runner bean (Phaseolus coccineus) and bindweed (Convolvulus species), while others twine anticlockwise, including French bean (Phaseolus vulgaris) and climbing honeysuckles (Lonicera species).
The contrasting rotations of bindweed and honeysuckle was the theme of the satirical song “Misalliance”,[15] written and sung by Michael Flanders and Donald Swann.
Horticultural climbing plants[edit]
The term “vine” also applies to cucurbitaceae like cucumbers where botanists refer to creeping vines; in commercial agriculture the natural tendency of coiling tendrils to attach themselves to pre-existing structures or espaliers is optimized by the installation of trellis netting.
Gardeners can use the tendency of climbing plants to grow quickly. If a plant display is wanted quickly, a climber can achieve this. Climbers can be trained over walls, pergolas, fences, etc. Climbers can be grown over other plants to provide additional attraction. Artificial support can also be provided. Some climbers climb by themselves; others need work, such as tying them in and training them.
Scientific description[edit]
This section needs attention from an expert in plants. The specific problem is: It is the work of a student editor, it needs verification, and may be overly technical for this article. WikiProject Plants may be able to help recruit an expert. (May 2018)
Vines widely differ in size, form and evolutionary origin. Darwin classified climbing groups based on their climbing method. He classified five classes of vines – twining plants, leaf climbers, tendril bearers, root climbers and hook climbers.
Vines are unique in that they have multiple evolutionary origins. They usually reside in tropical locations and have the unique ability to climb. Vines are able to grow in both deep shade and full sun due to their uniquely wide range of phenotypic plasticity. This climbing action prevents shading by neighbors and allows the vine to grow out of reach of herbivores.[16] The environment where a vine can grow successfully is determined by the climbing mechanism of a vine and how far it can spread across supports. There are many theories supporting the idea that photosynthetic responses are closely related to climbing mechanisms.
Temperate twining vines, which twist tightly around supports, are typically poorly adapted for climbing beneath closed canopies due to their smaller support diameter and shade intolerance. In contrast, tendril vines usually grow on the forest floor and onto trees until they reach the surface of the canopy, suggesting that they have greater physiological plasticity.[17] It has also been suggested that twining vines’ revolving growth is mediated by changes in turgor pressure mediated by volume changes in the epidermal cells of the bending zone.[18]
Climbing vines can take on many unique characteristics in response to changes in their environments. Climbing vines can induce chemical defenses and modify their biomass allocation in response to herbivores. In particular, the twisting vine C. arvensis increases its twining in response to herbivore-associated leaf damage, which may lead to reduced future herbivory.[19] Additionally, the tendrils of perennial vine Cayratia japonica are more likely to coil around nearby plants of another species than nearby plants of the same species in natural and experimental settings. This ability, which has only been previously documented in roots, demonstrates the vine’s ability to distinguish whether another plant is of the same species as itself or a different one.
In tendrilled vines, the tendrils are highly sensitive to touch and the coiling action is mediated by the hormones octadecanoids, jasmonates and indole-3-acetic acid. The touch stimulus and hormones may interact via volatile compounds or internal oscillation patterns.[20] Research has found the presence of ion translocating ATPases in the Bryonia dioica species of plants, which has implications for a possible ion mediation tendril curling mechanism. In response to a touch stimulus, vanadate sensitive K+, Mg2+ ATPase and a Ca2+ translocating ATPase rapidly increase their activity.
.
This increases transmembrane ion fluxes that appear to be involved in the early stages of tendril coiling.
.
Example vine taxa[edit]
Actinidia arguta, the tara vine
Aconitum Bulbuliferum
Actinidia polygama, the silver vine
Adlumia fungosa, the Allegheny vine
Aeschynanthus radicans, the lipstick vine
Akebia, the chocolate vine
Ampelocissus acetosa, known as wild grape or djabaru
Ampelopsis glandulosa var. brevipedunculata, known as wild grape or porcelain berry
Anredera cordifolia
Antigonon, the coral vine
Antigonon leptopus, the confederate vine
Aptenia cordifolia, the heart-leaved aptenia
Berchemia scandens, the rattan vine
Bignonia, the cross vine
Bougainvillea, a genus of thorny ornamental vines, bushes, and trees
Campsis, the trumpet vine
Campsis grandiflora, the Chinese trumpet vine
Cardiospermum halicacabum, the balloon vine
Celastrus, the staff vine
Ceropegia linearis, the rosary vine or sweetheart vine
Cissus antarctica, the kangaroo vine
Cissus hypoglauca, the water vine
Citrullus lanatus var. lanatus, the watermelon
Cucumis sativus, the cucumber
Cyphostemma juttae, known as wild grape
Epipremnum aureum, known as silver vine
Fallopia baldschuanica, the Russian vine
Ficus pumila, known as the climbing fig
Hedera helix, known as common ivy, English ivy, European ivy, or ivy
Ipomoea cairica, known as Cairo morning glory, coast morning glory and railroad creeper
Kennedia coccinea, the common coral vine
Lagenaria siceraria, known as the bottle gourd, calabash, opo squash, or long melon
Lathyrus odoratus, the sweet pea
Lonicera japonica, known as Suikazura or Japanese honeysuckle
Luffa, a genus of tropical and subtropical vines classified in the cucumber family, Cucurbitaceae
Lygodium, a genus of about 40 species of ferns, known as climbing ferns
Momordica charantia, the bitter gourd
Mikania scandens, the hemp vine
Muehlenbeckia adpressa, the macquarie vine
Nepenthes, a genus of carnivorous plants known as tropical pitcher plants or monkey cups
Pandorea pandorana, the wonga wonga vine
Parthenocissus quinquefolia, known as the Virginia creeper, Victoria creeper, five-leaved ivy, or five-finger
Passiflora edulis, the passion fruit
Periploca graeca, the silk vine
Podranea ricasoliana, the pink trumpet vine
Pueraria lobata, the kudzu vine
Scindapsus pictus, the silver vine
Sechium edule, known as chayote, christophene, or several other names
Senecio angulatus, known as Cape ivy
Solandra, a genus of flowering plants in the nightshade family
Solanum laxum, the potato vine
Strongylodon macrobotrys, the jade vine
Syngonium, the goosefoot vine
Syngonium podophyllum, the arrowhead vine
Thunbergia grandiflora, known as the Bengal clock vine or blue trumpet vine
Thunbergia erecta, the bush clock vine
Toxicodendron radicans, known as poison ivy
Vitis, any of about sixty species of grape
Wisteria, a genus of flowering plants in the pea family
See also[edit]
Vine (disambiguation)
Liana, any of various long-stemmed, woody vines
Nutation (botany), bending and growth patterns of plants, which dictate the growth of vines.
On the Movements and Habits of Climbing Plants, by Charles Darwin
List of world’s longest vines
Vine training systems
Pergola
Trellis (architecture)
References[edit]
^ Brown, Lesley (1993). The New shorter Oxford English dictionary on historical principles. Oxford [Eng.]: Clarendon. ISBN 0-19-861271-0.
^ Jackson; Benjamin; Daydon (1928). A Glossary of Botanic Terms with their Derivation and Accent, 4th ed. London: Gerald Duckworth & Co.
^ Francis E. Putz (1991). The Biology of Vines. Cambridge University Press. pp. xiii. ISBN 978-0-521-39250-1. Using ‘vines’ to denote all climbing plants may initially confuse some readers from lands where, with due respect for wine, ‘the vine’ is used solely in reference to grapes.
^ Shorter Oxford English dictionary, 6th ed. Oxford, UK: Oxford University Press. 2007. p. 3804. ISBN 978-0199206872.
^ “Creepers”. mannuthynursery. Retrieved 17 July 2013.
^ Glimn-Lacy, Janice; Kaufman, Peter B. (2006). Botany Illustrated. Springer. doi:10.1007/0-387-28875-9. ISBN 978-0-387-28870-3.
^ Gianoli, Ernesto (2004). “Evolution of a climbing habit promotes diversification in flowering plants”. Proceedings of the Royal Society B: Biological Sciences. 271 (1552): 2011–2015. doi:10.1098/rspb.2004.2827. JSTOR 4142967. PMC 1691831. PMID 15451690.
^ Putz, Francis E. “Vine Ecology”. Retrieved 1 March 2012.
^ Weakley, Alan (2010). Flora of the Southern and Mid-Atlantic States (PDF). p. 661.
^ “Japanese climbing fern”. Center for Aquatic and Invasive Plants. Retrieved 17 July 2013.
^ Haldeman, Jan. “As the vine twines”. Native and Naturalized Plants of the Carolinas and Georgia. Retrieved 16 January 2018.
^ Weakley, Alan S. (May 2015). Flora of the Southern and Mid-Atlantic States. UNC Herbarium, North Carolina Botanical Garden, University of North Carolina at Chapel Hill. Retrieved 16 January 2018.
^ bine at Merriam-Webster
^ Cone Heads at Willamette Week
^ Misalliance
^ Gianoli, Ernesto; Molina-Montenegro, Marco A. (2005). “Leaf Damage Induces Twining in a Climbing Plant”. The New Phytologist. 167 (2): 385–90. doi:10.1111/j.1469-8137.2005.01484.x. JSTOR 3694507. PMID 15998392.
^ Carter, Gregory A.; Teramura, Alan H. (1988). “Vine Photosynthesis and Relationships to Climbing Mechanisms in a Forest Understory”. American Journal of Botany. 75 (7): 1101. doi:10.2307/2443769. JSTOR 2443769.
^ Millet, B.; Melin, D.; Badot, P.-M. (1988). “Circumnutation in Phaseolus vulgaris. I. Growth, osmotic potential and cell ultrastructure in the free moving part of the shoot”. Physiologia Plantarum. 72: 133–138. doi:10.1111/j.1399-3054.1988.tb06634.x.
^ Molina-Montenegro, Marco A.; Gianoli, Ernesto; Becerra, José (2007). “Interactive Effects of Leaf Damage, Light Intensity and Support Availability on Chemical Defenses and Morphology of a Twining Vine”. Journal of Chemical Ecology. 33 (1): 95–103. doi:10.1007/s10886-006-9215-8. PMID 17111219. S2CID 27419071.
^ Fukano, Yuya; Yamawo, Akira (26 August 2015). “Self-discrimination in the tendrils of the vine is mediated by physiological connection”. Proceedings of the Royal Society B: Biological Sciences. 282 (1814): 20151379. doi:10.1098/rspb.2015.1379. PMC 4571702. PMID 26311669.
^ Liß, H.; Weiler, E. W. (July 1994). “Ion-translocating ATPases in tendrils of Bryonia dioica Jacq”. Planta. 194 (2): 169–180. doi:10.1007/BF00196385. JSTOR 23383001. S2CID 25162242.
External links[edit]
Look up vine in Wiktionary,
the free dictionary
en.wikipedia.org /wiki/Vine
Vine
Contributors to Wikimedia projects
14-18 minutes
This article is about climbing plants in general. For grapevines, see Vitis.
For other uses, see Vine (disambiguation)
.
*LEAF*
.
en.wikipedia.org /wiki/Leaf
Leaf
Contributors to Wikimedia projects
67-85 minutes
Diagram of a simple leaf.
Apex
Midvein (Primary vein)
Secondary vein.
Lamina.
Leaf margin
Petiole
Bud
Stem
Top and Right: Staghorn Sumac, Rhus typhina (Compound Leaf)
Bottom: Skunk Cabbage, Symplocarpus foetidus (Simple Leaf)
- Apex
- Primary Vein
- Secondary Vein
- Lamina
- Leaf Margin
- Petiole
A leaf (plural leaves) is the principal lateral appendage of the vascular plant stem,[1] usually borne above ground and specialized for photosynthesis. The leaves and stem together form the shoot.[2] Leaves are collectively referred to as foliage, as in “autumn foliage”.[3][4] In most leaves, the primary photosynthetic tissue, the palisade mesophyll, is located on the upper side of the blade or lamina of the leaf[1] but in some species, including the mature foliage of Eucalyptus,[5] palisade mesophyll is present on both sides and the leaves are said to be isobilateral. Most leaves are flattened and have distinct upper (adaxial) and lower (abaxial) surfaces that differ in color, hairiness, the number of stomata (pores that intake and output gases), the amount and structure of epicuticular wax and other features. Leaves are mostly green in color due to the presence of a compound called chlorophyll that is essential for photosynthesis as it absorbs light energy from the sun. A leaf with white patches or edges is called a variegated leaf.
Leaves can have many different shapes, sizes, and textures. The broad, flat leaves with complex venation of flowering plants are known as megaphylls and the species that bear them, the majority, as broad-leaved or megaphyllous plants. In the clubmosses, with different evolutionary origins, the leaves are simple (with only a single vein) and are known as microphylls.[6] Some leaves, such as bulb scales, are not above ground. In many aquatic species, the leaves are submerged in water. Succulent plants often have thick juicy leaves, but some leaves are without major photosynthetic function and may be dead at maturity, as in some cataphylls and spines. Furthermore, several kinds of leaf-like structures found in vascular plants are not totally homologous with them. Examples include flattened plant stems called phylloclades and cladodes, and flattened leaf stems called phyllodes which differ from leaves both in their structure and origin.[4][7] Some structures of non-vascular plants look and function much like leaves. Examples include the phyllids of mosses and liverworts.
General characteristics[edit]
Leaves are the most important organs of most vascular plants.[8] Green plants are autotrophic, meaning that they do not obtain food from other living things but instead create their own food by photosynthesis. They capture the energy in sunlight and use it to make simple sugars, such as glucose and sucrose, from carbon dioxide and water. The sugars are then stored as starch, further processed by chemical synthesis into more complex organic molecules such as proteins or cellulose, the basic structural material in plant cell walls, or metabolized by cellular respiration to provide chemical energy to run cellular processes. The leaves draw water from the ground in the transpiration stream through a vascular conducting system known as xylem and obtain carbon dioxide from the atmosphere by diffusion through openings called stomata in the outer covering layer of the leaf (epidermis), while leaves are orientated to maximize their exposure to sunlight. Once sugar has been synthesized, it needs to be transported to areas of active growth such as the plant shoots and roots. Vascular plants transport sucrose in a special tissue called the phloem. The phloem and xylem are parallel to each other, but the transport of materials is usually in opposite directions. Within the leaf these vascular systems branch (ramify) to form veins which supply as much of the leaf as possible, ensuring that cells carrying out photosynthesis are close to the transportation system.[9]
Typically leaves are broad, flat and thin (dorsiventrally flattened), thereby maximising the surface area directly exposed to light and enabling the light to penetrate the tissues and reach the chloroplasts, thus promoting photosynthesis. They are arranged on the plant so as to expose their surfaces to light as efficiently as possible without shading each other, but there are many exceptions and complications. For instance, plants adapted to windy conditions may have pendent leaves, such as in many willows and eucalypts. The flat, or laminar, shape also maximizes thermal contact with the surrounding air, promoting cooling. Functionally, in addition to carrying out photosynthesis, the leaf is the principal site of transpiration, providing the energy required to draw the transpiration stream up from the roots, and guttation.
Many gymnosperms have thin needle-like or scale-like leaves that can be advantageous in cold climates with frequent snow and frost.[10] These are interpreted as reduced from megaphyllous leaves of their Devonian ancestors.[6] Some leaf forms are adapted to modulate the amount of light they absorb to avoid or mitigate excessive heat, ultraviolet damage, or desiccation, or to sacrifice light-absorption efficiency in favor of protection from herbivory. For xerophytes the major constraint is not light flux or intensity, but drought.[11] Some window plants such as Fenestraria species and some Haworthia species such as Haworthia tesselata and Haworthia truncata are examples of xerophytes.[12] and Bulbine mesembryanthemoides.[13]
Leaves also function to store chemical energy and water (especially in succulents) and may become specialized organs serving other functions, such as tendrils of peas and other legumes, the protective spines of cacti and the insect traps in carnivorous plants such as Nepenthes and Sarracenia.[14] Leaves are the fundamental structural units from which cones are constructed in gymnosperms (each cone scale is a modified megaphyll leaf known as a sporophyll)[6]:408 and from which flowers are constructed in flowering plants.[6]:445
Vein skeleton of a leaf. Veins contain lignin that make them harder to degrade for microorganisms.
The internal organization of most kinds of leaves has evolved to maximize exposure of the photosynthetic organelles, the chloroplasts, to light and to increase the absorption of carbon dioxide while at the same time controlling water loss. Their surfaces are waterproofed by the plant cuticle and gas exchange between the mesophyll cells and the atmosphere is controlled by minute (length and width measured in tens of µm) openings called stomata which open or close to regulate the rate exchange of carbon dioxide, oxygen, and water vapor into and out of the internal intercellular space system. Stomatal opening is controlled by the turgor pressure in a pair of guard cells that surround the stomatal aperture. In any square centimeter of a plant leaf, there may be from 1,000 to 100,000 stomata.[15]
Near the ground these Eucalyptus saplings have juvenile dorsiventral foliage from the previous year, but this season their newly sprouting foliage is isobilateral, like the mature foliage on the adult trees above
The shape and structure of leaves vary considerably from species to species of plant, depending largely on their adaptation to climate and available light, but also to other factors such as grazing animals (such as deer), available nutrients, and ecological competition from other plants. Considerable changes in leaf type occur within species, too, for example as a plant matures; as a case in point Eucalyptus species commonly have isobilateral, pendent leaves when mature and dominating their neighbors; however, such trees tend to have erect or horizontal dorsiventral leaves as seedlings, when their growth is limited by the available light.[16] Other factors include the need to balance water loss at high temperature and low humidity against the need to absorb atmospheric carbon dioxide. In most plants, leaves also are the primary organs responsible for transpiration and guttation (beads of fluid forming at leaf margins).
Leaves can also store food and water, and are modified accordingly to meet these functions, for example in the leaves of succulent plants and in bulb scales. The concentration of photosynthetic structures in leaves requires that they be richer in protein, minerals, and sugars than, say, woody stem tissues. Accordingly, leaves are prominent in the diet of many animals.
Correspondingly, leaves represent heavy investment on the part of the plants bearing them, and their retention or disposition are the subject of elaborate strategies for dealing with pest pressures, seasonal conditions, and protective measures such as the growth of thorns and the production of phytoliths, lignins, tannins and poisons.
Deciduous plants in frigid or cold temperate regions typically shed their leaves in autumn, whereas in areas with a severe dry season, some plants may shed their leaves until the dry season ends. In either case, the shed leaves may be expected to contribute their retained nutrients to the soil where they fall.
In contrast, many other non-seasonal plants, such as palms and conifers, retain their leaves for long periods; Welwitschia retains its two main leaves throughout a lifetime that may exceed a thousand years.
The leaf-like organs of bryophytes (e.g., mosses and liverworts), known as phyllids, differ morphologically from the leaves of vascular plants in that they lack vascular tissue, are usually only a single cell thick, and have no cuticle stomata or internal system of intercellular spaces. The leaves of bryophytes are only present on the gametophytes, while in contrast the leaves of vascular plants are only present on the sporophytes, and are associated with buds (immature shoot systems in the leaf axils). These can further develop into either vegetative or reproductive structures.[14]
Simple, vascularized leaves (microphylls), such as those of the early Devonian lycopsid Baragwanathia, first evolved as enations, extensions of the stem. True leaves or euphylls of larger size and with more complex venation did not become widespread in other groups until the Devonian period, by which time the carbon dioxide concentration in the atmosphere had dropped significantly. This occurred independently in several separate lineages of vascular plants, in progymnosperms like Archaeopteris, in Sphenopsida, ferns and later in the gymnosperms and angiosperms. Euphylls are also referred to as macrophylls or megaphylls (large leaves).[6]
Morphology[edit]
Leafstem of dog rose with petiole, stipules and leaflets
A structurally complete leaf of an angiosperm consists of a petiole (leaf stalk), a lamina (leaf blade), stipules (small structures located to either side of the base of the petiole) and a sheath. Not every species produces leaves with all of these structural components. The proximal stalk or petiole is called a stipe in ferns. The lamina is the expanded, flat component of the leaf which contains the chloroplasts. The sheath is a structure, typically at the base that fully or partially clasps the stem above the node, where the latter is attached. Leaf sheathes typically occur in grasses and Apiaceae (umbellifers). Between the sheath and the lamina, there may be a pseudopetiole, a petiole like structure. Pseudopetioles occur in some monocotyledons including bananas, palms and bamboos.[18] Stipules may be conspicuous (e.g. beans and roses), soon falling or otherwise not obvious as in Moraceae or absent altogether as in the Magnoliaceae. A petiole may be absent (apetiolate), or the blade may not be laminar (flattened). The tremendous variety shown in leaf structure (anatomy) from species to species is presented in detail below under morphology. The petiole mechanically links the leaf to the plant and provides the route for transfer of water and sugars to and from the leaf. The lamina is typically the location of the majority of photosynthesis. The upper (adaxial) angle between a leaf and a stem is known as the axil of the leaf. It is often the location of a bud. Structures located there are called “axillary”.
External leaf characteristics, such as shape, margin, hairs, the petiole, and the presence of stipules and glands, are frequently important for identifying plants to family, genus or species levels, and botanists have developed a rich terminology for describing leaf characteristics. Leaves almost always have determinate growth. They grow to a specific pattern and shape and then stop. Other plant parts like stems or roots have non-determinate growth, and will usually continue to grow as long as they have the resources to do so.
The type of leaf is usually characteristic of a species (monomorphic), although some species produce more than one type of leaf (dimorphic or polymorphic). The longest leaves are those of the Raffia palm, R. regalis which may be up to 25 m (82 ft) long and 3 m (9.8 ft) wide.[19] The terminology associated with the description of leaf morphology is presented, in illustrated form, at Wikibooks.
Where leaves are basal, and lie on the ground, they are referred to as prostrate.
Basic leaf types[edit]
Perennial plants whose leaves are shed annually are said to have deciduous leaves, while leaves that remain through winter are evergreens. Leaves attached to stems by stalks (known as petioles) are called petiolate, and if attached directly to the stem with no petiole they are called sessile.[20]
Ferns have fronds.
Conifer leaves are typically needle- or awl-shaped or scale-like, they are usually evergreen, but can sometimes be deciduous. Usually, they have a single vein.
Flowering plant (Angiosperm) leaves: the standard form includes stipules, a petiole, and a lamina.
Lycophytes have microphylls.
Sheath leaves are the type found in most grasses and many other monocots.
Other specialized leaves include those of Nepenthes, a pitcher plant.
Dicot leaves have blades with pinnate vegetation (where major veins diverge from one large mid-vein and have smaller connecting networks between them). Less commonly, dicot leaf blades may have palmate venation (several large veins diverging from petiole to leaf edges). Finally, some exhibit parallel venation.[20]
Monocot leaves in temperate climates usually have narrow blades, and usually parallel venation converging at leaf tips or edges. Some also have pinnate venation.[20]
Arrangement on the stem[edit]
Different terms are usually used to describe the arrangement of leaves on the stem (phyllotaxis):
The leaves on this plant are arranged in pairs opposite one another, with successive pairs at right angles to each other (decussate) along the red stem. Note the developing buds in the axils of these leaves.
Alternate
One leaf, branch, or flower part attaches at each point or node on the stem, and leaves alternate direction, to a greater or lesser degree, along the stem.
Basal
Arising from the base of the stem.
Cauline
Arising from the aerial stem.
Opposite
Two leaves, branches, or flower parts attach at each point or node on the stem. Leaf attachments are paired at each node and decussate if, as typical, each successive pair is rotated 90° progressing along the stem.
Whorled, or verticillate
Three or more leaves, branches, or flower parts attach at each point or node on the stem. As with opposite leaves, successive whorls may or may not be decussate, rotated by half the angle between the leaves in the whorl (i.e., successive whorls of three rotated 60°, whorls of four rotated 45°, etc.). Opposite leaves may appear whorled near the tip of the stem. Pseudoverticillate describes an arrangement only appearing whorled, but not actually so.
Rosulate
Leaves form a rosette.
Rows
The term, distichous, literally means two rows. Leaves in this arrangement may be alternate or opposite in their attachment. The term, 2-ranked, is equivalent. The terms, tristichous and tetrastichous, are sometimes encountered. For example, the “leaves” (actually microphylls) of most species of Selaginella are tetrastichous, but not decussate.
As a stem grows, leaves tend to appear arranged around the stem in a way that optimizes yield of light. In essence, leaves form a helix pattern centered around the stem, either clockwise or counterclockwise, with (depending upon the species) the same angle of divergence. There is a regularity in these angles and they follow the numbers in a Fibonacci sequence: 1/2, 2/3, 3/5, 5/8, 8/13, 13/21, 21/34, 34/55, 55/89. This series tends to the golden angle, which is approximately 360° × 34/89 ≈ 137.52° ≈ 137° 30′. In the series, the numerator indicates the number of complete turns or “gyres” until a leaf arrives at the initial position and the denominator indicates the number of leaves in the arrangement. This can be demonstrated by the following:
Alternate leaves have an angle of 180° (or 1⁄2)
120° (or 1⁄3): three leaves in one circle
144° (or 2⁄5): five leaves in two gyres
135° (or 3⁄8): eight leaves in three gyres.
Divisions of the blade[edit]
A leaf with laminar structure and pinnate venation
Two basic forms of leaves can be described considering the way the blade (lamina) is divided. A simple leaf has an undivided blade. However, the leaf may be dissected to form lobes, but the gaps between lobes do not reach to the main vein. A compound leaf has a fully subdivided blade, each leaflet of the blade being separated along a main or secondary vein. The leaflets may have petiolules and stipels, the equivalents of the petioles and stipules of leaves. Because each leaflet can appear to be a simple leaf, it is important to recognize where the petiole occurs to identify a compound leaf. Compound leaves are a characteristic of some families of higher plants, such as the Fabaceae. The middle vein of a compound leaf or a frond, when it is present, is called a rachis.
Palmately compound
Leaves have the leaflets radiating from the end of the petiole, like fingers of the palm of a hand; for example, Cannabis (hemp) and Aesculus (buckeyes).
Pinnately compound
Leaves have the leaflets arranged along the main or mid-vein.
Odd pinnate
With a terminal leaflet; for example, Fraxinus (ash).
Even pinnate
Lacking a terminal leaflet; for example, Swietenia (mahogany). A specific type of even pinnate is bipinnate, where leaves only consist of two leaflets; for example, Hymenaea.
Bipinnately compound
Leaves are twice divided: the leaflets are arranged along a secondary vein that is one of several branching off the rachis. Each leaflet is called a pinnule. The group of pinnules on each secondary vein forms a pinna; for example, Albizia (silk tree).
Trifoliate (or trifoliolate)
A pinnate leaf with just three leaflets; for example, Trifolium (clover), Laburnum (laburnum), and some species of Toxicodendron (for instance, poison ivy).
Pinnatifid
Pinnately dissected to the central vein, but with the leaflets not entirely separate; for example, Polypodium, some Sorbus (whitebeams). In pinnately veined leaves the central vein in known as the midrib.
Characteristics of the petiole[edit]
The overgrown petioles of rhubarb (Rheum rhabarbarum) are edible.
Petiolated leaves have a petiole (leaf stalk), and are said to be petiolate.
Sessile (epetiolate) leaves have no petiole and the blade attaches directly to the stem. Subpetiolate leaves are nearly petiolate or have an extremely short petiole and may appear to be sessile.
In clasping or decurrent leaves, the blade partially surrounds the stem.
When the leaf base completely surrounds the stem, the leaves are said to be perfoliate, such as in Eupatorium perfoliatum.
In peltate leaves, the petiole attaches to the blade inside the blade margin.
In some Acacia species, such as the koa tree (Acacia koa), the petioles are expanded or broadened and function like leaf blades; these are called phyllodes. There may or may not be normal pinnate leaves at the tip of the phyllode.
A stipule, present on the leaves of many dicotyledons, is an appendage on each side at the base of the petiole, resembling a small leaf. Stipules may be lasting and not be shed (a stipulate leaf, such as in roses and beans), or be shed as the leaf expands, leaving a stipule scar on the twig (an exstipulate leaf). The situation, arrangement, and structure of the stipules is called the “stipulation”.
Free, lateral
As in Hibiscus.
Adnate
Fused to the petiole base, as in Rosa.
Ochreate
Provided with ochrea, or sheath-formed stipules, as in Polygonaceae; e.g., rhubarb.
Encircling the petiole base
Interpetiolar
Between the petioles of two opposite leaves, as in Rubiaceae.
Intrapetiolar
Between the petiole and the subtending stem, as in Malpighiaceae.
Veins[edit]
Branching veins on underside of taro leaf
Veins (sometimes referred to as nerves) constitute one of the more visible leaf traits or characteristics. The veins in a leaf represent the vascular structure of the organ, extending into the leaf via the petiole and providing transportation of water and nutrients between leaf and stem, and play a crucial role in the maintenance of leaf water status and photosynthetic capacity.They also play a role in the mechanical support of the leaf.[21][22] Within the lamina of the leaf, while some vascular plants possess only a single vein, in most this vasculature generally divides (ramifies) according to a variety of patterns (venation) and form cylindrical bundles, usually lying in the median plane of the mesophyll, between the two layers of epidermis.[23] This pattern is often specific to taxa, and of which angiosperms possess two main types, parallel and reticulate (net like). In general, parallel venation is typical of monocots, while reticulate is more typical of eudicots and magnoliids (“dicots”), though there are many exceptions.[24][23][25]
The vein or veins entering the leaf from the petiole are called primary or first-order veins. The veins branching from these are secondary or second-order veins. These primary and secondary veins are considered major veins or lower order veins, though some authors include third order.[26] Each subsequent branching is sequentially numbered, and these are the higher order veins, each branching being associated with a narrower vein diameter.[27] In parallel veined leaves, the primary veins run parallel and equidistant to each other for most of the length of the leaf and then converge or fuse (anastomose) towards the apex. Usually, many smaller minor veins interconnect these primary veins, but may terminate with very fine vein endings in the mesophyll. Minor veins are more typical of angiosperms, which may have as many as four higher orders.[26] In contrast, leaves with reticulate venation there is a single (sometimes more) primary vein in the centre of the leaf, referred to as the midrib or costa and is continuous with the vasculature of the petiole more proximally. The midrib then branches to a number of smaller secondary veins, also known as second order veins, that extend toward the leaf margins. These often terminate in a hydathode, a secretory organ, at the margin. In turn, smaller veins branch from the secondary veins, known as tertiary or third order (or higher order) veins, forming a dense reticulate pattern. The areas or islands of mesophyll lying between the higher order veins, are called areoles. Some of the smallest veins (veinlets) may have their endings in the areoles, a process known as areolation.[27] These minor veins act as the sites of exchange between the mesophyll and the plant’s vascular system.[22] Thus, minor veins collect the products of photosynthesis (photosynthate) from the cells where it takes place, while major veins are responsible for its transport outside of the leaf. At the same time water is being transported in the opposite direction.[28][24][23]
The number of vein endings is very variable, as is whether second order veins end at the margin, or link back to other veins.[25] There are many elaborate variations on the patterns that the leaf veins form, and these have functional implications. Of these, angiosperms have the greatest diversity.[26] Within these the major veins function as the support and distribution network for leaves and are correlated with leaf shape. For instance, the parallel venation found in most monocots correlates with their elongated leaf shape and wide leaf base, while reticulate venation is seen in simple entire leaves, while digitate leaves typically have venation in which three or more primary veins diverge radially from a single point.[29][22][27][30]
In evolutionary terms, early emerging taxa tend to have dichotomous branching with reticulate systems emerging later. Veins appeared in the Permian period (299–252 mya), prior to the appearance of angiosperms in the Triassic (252–201 mya), during which vein hierarchy appeared enabling higher function, larger leaf size and adaption to a wider variety of climatic conditions.[26] Although it is the more complex pattern, branching veins appear to be plesiomorphic and in some form were present in ancient seed plants as long as 250 million years ago. A pseudo-reticulate venation that is actually a highly modified penniparallel one is an autapomorphy of some Melanthiaceae, which are monocots; e.g., Paris quadrifolia (True-lover’s Knot). In leaves with reticulate venation, veins form a scaffolding matrix imparting mechanical rigidity to leaves.[31]
Morphology changes within a single plant[edit]
Homoblasty
Characteristic in which a plant has small changes in leaf size, shape, and growth habit between juvenile and adult stages, in contrast to;
Heteroblasty
Characteristic in which a plant has marked changes in leaf size, shape, and growth habit between juvenile and adult stages.
Anatomy[edit]
Medium-scale features[edit]
Leaves are normally extensively vascularized and typically have networks of vascular bundles containing xylem, which supplies water for photosynthesis, and phloem, which transports the sugars produced by photosynthesis. Many leaves are covered in trichomes (small hairs) which have diverse structures and functions.
Medium scale diagram of leaf internal anatomy
Small-scale features[edit]
The major tissue systems present are
The epidermis, which covers the upper and lower surfaces
The mesophyll tissue inside the leaf, which is rich in chloroplasts (also called chlorenchyma)
The arrangement of veins (the vascular tissue)
These three tissue systems typically form a regular organization at the cellular scale. Specialized cells that differ markedly from surrounding cells, and which often synthesize specialized products such as crystals, are termed idioblasts.[32]
Fine scale diagram of leaf structure
Major leaf tissues[edit]
Cross-section of a leaf
Epidermal cells
Spongy mesophyll cells
Epidermis[edit]
The epidermis is the outer layer of cells covering the leaf. It is covered with a waxy cuticle which is impermeable to liquid water and water vapor and forms the boundary separating the plant’s inner cells from the external world. The cuticle is in some cases thinner on the lower epidermis than on the upper epidermis, and is generally thicker on leaves from dry climates as compared with those from wet climates.[33] The epidermis serves several functions: protection against water loss by way of transpiration, regulation of gas exchange and secretion of metabolic compounds. Most leaves show dorsoventral anatomy: The upper (adaxial) and lower (abaxial) surfaces have somewhat different construction and may serve different functions.
The epidermis tissue includes several differentiated cell types; epidermal cells, epidermal hair cells (trichomes), cells in the stomatal complex; guard cells and subsidiary cells. The epidermal cells are the most numerous, largest, and least specialized and form the majority of the epidermis. They are typically more elongated in the leaves of monocots than in those of dicots.
Chloroplasts are generally absent in epidermal cells, the exception being the guard cells of the stomata. The stomatal pores perforate the epidermis and are surrounded on each side by chloroplast-containing guard cells, and two to four subsidiary cells that lack chloroplasts, forming a specialized cell group known as the stomatal complex. The opening and closing of the stomatal aperture is controlled by the stomatal complex and regulates the exchange of gases and water vapor between the outside air and the interior of the leaf. Stomata therefore play the important role in allowing photosynthesis without letting the leaf dry out. In a typical leaf, the stomata are more numerous over the abaxial (lower) epidermis than the adaxial (upper) epidermis and are more numerous in plants from cooler climates.
Mesophyll[edit]
For the term Mesophyll in the size classification of leaves, see Leaf size.
Most of the interior of the leaf between the upper and lower layers of epidermis is a parenchyma (ground tissue) or chlorenchyma tissue called the mesophyll (Greek for “middle leaf”). This assimilation tissue is the primary location of photosynthesis in the plant. The products of photosynthesis are called “assimilates”.
In ferns and most flowering plants, the mesophyll is divided into two layers:
An upper palisade layer of vertically elongated cells, one to two cells thick, directly beneath the adaxial epidermis, with intercellular air spaces between them. Its cells contain many more chloroplasts than the spongy layer. Cylindrical cells, with the chloroplasts close to the walls of the cell, can take optimal advantage of light. The slight separation of the cells provides maximum absorption of carbon dioxide. Sun leaves have a multi-layered palisade layer, while shade leaves or older leaves closer to the soil are single-layered.
Beneath the palisade layer is the spongy layer. The cells of the spongy layer are more branched and not so tightly packed, so that there are large intercellular air spaces between them. The pores or stomata of the epidermis open into substomatal chambers, which are connected to the intercellular air spaces between the spongy and palisade mesophyll cell, so that oxygen, carbon dioxide and water vapor can diffuse into and out of the leaf and access the mesophyll cells during respiration, photosynthesis and transpiration.
Leaves are normally green, due to chlorophyll in chloroplasts in the mesophyll cells. Plants that lack chlorophyll cannot photosynthesize.
Vascular tissue[edit]
The veins are the vascular tissue of the leaf and are located in the spongy layer of the mesophyll. The pattern of the veins is called venation. In angiosperms the venation is typically parallel in monocotyledons and forms an interconnecting network in broad-leaved plants. They were once thought to be typical examples of pattern formation through ramification, but they may instead exemplify a pattern formed in a stress tensor field.[34][35][36]
A vein is made up of a vascular bundle. At the core of each bundle are clusters of two distinct types of conducting cells:
Xylem
Cells that bring water and minerals from the roots into the leaf.
Phloem
Cells that usually move sap, with dissolved sucrose(glucose to sucrose) produced by photosynthesis in the leaf, out of the leaf.
The xylem typically lies on the adaxial side of the vascular bundle and the phloem typically lies on the abaxial side. Both are embedded in a dense parenchyma tissue, called the sheath, which usually includes some structural collenchyma tissue.
Leaf development[edit]
According to Agnes Arber’s partial-shoot theory of the leaf, leaves are partial shoots,[37] being derived from leaf primordia of the shoot apex. Early in development they are dorsiventrally flattened with both dorsal and ventral surfaces.[14] Compound leaves are closer to shoots than simple leaves. Developmental studies have shown that compound leaves, like shoots, may branch in three dimensions.[38][39] On the basis of molecular genetics, Eckardt and Baum (2010) concluded that “it is now generally accepted that compound leaves express both leaf and shoot properties.”[40]
Ecology[edit]
Biomechanics[edit]
Plants respond and adapt to environmental factors, such as light and mechanical stress from wind. Leaves need to support their own mass and align themselves in such a way as to optimize their exposure to the sun, generally more or less horizontally. However, horizontal alignment maximizes exposure to bending forces and failure from stresses such as wind, snow, hail, falling debris, animals, and abrasion from surrounding foliage and plant structures. Overall leaves are relatively flimsy with regard to other plant structures such as stems, branches and roots.[41]
Both leaf blade and petiole structure influence the leaf’s response to forces such as wind, allowing a degree of repositioning to minimize drag and damage, as opposed to resistance. Leaf movement like this may also increase turbulence of the air close to the surface of the leaf, which thins the boundary layer of air immediately adjacent to the surface, increasing the capacity for gas and heat exchange, as well as photosynthesis. Strong wind forces may result in diminished leaf number and surface area, which while reducing drag, involves a trade off of also reducing photosynthesis. Thus, leaf design may involve compromise between carbon gain, thermoregulation and water loss on the one hand, and the cost of sustaining both static and dynamic loads. In vascular plants, perpendicular forces are spread over a larger area and are relatively flexible in both bending and torsion, enabling elastic deforming without damage.[41]
Many leaves rely on hydrostatic support arranged around a skeleton of vascular tissue for their strength, which depends on maintaining leaf water status. Both the mechanics and architecture of the leaf reflect the need for transportation and support. Read and Stokes (2006) consider two basic models, the “hydrostatic” and “I-beam leaf” form (see Fig 1).[41] Hydrostatic leaves such as in Prostanthera lasianthos are large and thin, and may involve the need for multiple leaves rather single large leaves because of the amount of veins needed to support the periphery of large leaves. But large leaf size favors efficiency in photosynthesis and water conservation, involving further trade offs. On the other hand, I-beam leaves such as Banksia marginata involve specialized structures to stiffen them. These I-beams are formed from bundle sheath extensions of sclerenchyma meeting stiffened sub-epidermal layers. This shifts the balance from reliance on hydrostatic pressure to structural support, an obvious advantage where water is relatively scarce. [41] Long narrow leaves bend more easily than ovate leaf blades of the same area. Monocots typically have such linear leaves that maximize surface area while minimising self-shading. In these a high proportion of longitudinal main veins provide additional support.[41]
Interactions with other organisms[edit]
Although not as nutritious as other organs such as fruit, leaves provide a food source for many organisms. The leaf is a vital source of energy production for the plant, and plants have evolved protection against animals that consume leaves, such as tannins, chemicals which hinder the digestion of proteins and have an unpleasant taste. Animals that are specialized to eat leaves are known as folivores.
Some species have cryptic adaptations by which they use leaves in avoiding predators. For example, the caterpillars of some leaf-roller moths will create a small home in the leaf by folding it over themselves. Some sawflies similarly roll the leaves of their food plants into tubes. Females of the Attelabidae, so-called leaf-rolling weevils, lay their eggs into leaves that they then roll up as means of protection. Other herbivores and their predators mimic the appearance of the leaf. Reptiles such as some chameleons, and insects such as some katydids, also mimic the oscillating movements of leaves in the wind, moving from side to side or back and forth while evading a possible threat.
Seasonal leaf loss[edit]
Leaves shifting color in autumn (fall)
Leaves in temperate, boreal, and seasonally dry zones may be seasonally deciduous (falling off or dying for the inclement season). This mechanism to shed leaves is called abscission. When the leaf is shed, it leaves a leaf scar on the twig. In cold autumns, they sometimes change color, and turn yellow, bright-orange, or red, as various accessory pigments (carotenoids and xanthophylls) are revealed when the tree responds to cold and reduced sunlight by curtailing chlorophyll production. Red anthocyanin pigments are now thought to be produced in the leaf as it dies, possibly to mask the yellow hue left when the chlorophyll is lost—yellow leaves appear to attract herbivores such as aphids.[42] Optical masking of chlorophyll by anthocyanins reduces risk of photo-oxidative damage to leaf cells as they senesce, which otherwise may lower the efficiency of nutrient retrieval from senescing autumn leaves.[43]
Evolutionary adaptation[edit]
Poinsettia bracts are leaves which have evolved red pigmentation in order to attract insects and birds to the central flowers, an adaptive function normally served by petals (which are themselves leaves highly modified by evolution).
In the course of evolution, leaves have adapted to different environments in the following ways:[citation needed]
Waxy micro- and nanostructures on the surface reduce wetting by rain and adhesion of contamination (See Lotus effect).
Divided and compound leaves reduce wind resistance and promote cooling.
Hairs on the leaf surface trap humidity in dry climates and create a boundary layer reducing water loss.
Waxy plant cuticles reduce water loss.
Large surface area provides a large area for capture of sunlight.
In harmful levels of sunlight, specialized leaves, opaque or partly buried, admit light through a translucent leaf window for photosynthesis at inner leaf surfaces (e.g. Fenestraria).
Kranz leaf anatomy in plants who perform C4 carbon fixation
Succulent leaves store water and organic acids for use in CAM photosynthesis.
Aromatic oils, poisons or pheromones produced by leaf borne glands deter herbivores (e.g. eucalypts).
Inclusions of crystalline minerals deter herbivores (e.g. silica phytoliths in grasses, raphides in Araceae).
Petals attract pollinators.
Spines protect the plants from herbivores (e.g. cacti).
Stinging hairs to protect against herbivory, e.g. in Urtica dioica and Dendrocnide moroides (Urticaceae).
Special leaves on carnivorous plants are adapted for trapping food, mainly invertebrate prey, though some species trap small vertebrates as well (see carnivorous plants).
Bulbs store food and water (e.g. onions).
Tendrils allow the plant to climb (e.g. peas).
Bracts and pseudanthia (false flowers) replace normal flower structures when the true flowers are greatly reduced (e.g. spurges and spathes in the Araceae.
Terminology[edit]
Shape[edit]
Leaves showing various morphologies. Clockwise from upper left: tripartite lobation, elliptic with serrulate margin, palmate venation, acuminate odd-pinnate (center), pinnatisect, lobed, elliptic with entire margin
Edge (margin)[edit]
Image Term Latin Description
Leaf morphology entire.png Entire Forma
integra Even; with a smooth margin; without toothing
Leaf morphology ciliate.png Ciliate Ciliata Fringed with hairs
Leaf morphology crenate.png Crenate Crenata Wavy-toothed; dentate with rounded teeth
Leaf morphology dentate.png Dentate Dentata Toothed
May be coarsely dentate, having large teeth
or glandular dentate, having teeth which bear glands
Leaf morphology denticulate.png Denticulate Denticulata Finely toothed
Leaf morphology doubly serrate.png Doubly serrate Duplicato-dentata Each tooth bearing smaller teeth
Leaf morphology serrate.png Serrate Serrata Saw-toothed; with asymmetrical teeth pointing forward
Leaf morphology serrulate.png Serrulate Serrulata Finely serrate
Leaf morphology sinuate.png Sinuate Sinuosa With deep, wave-like indentations; coarsely crenate
Leaf morphology lobate.png Lobate Lobata Indented, with the indentations not reaching the center
Leaf morphology undulate.png Undulate Undulata With a wavy edge, shallower than sinuate
Leaf morphology spiny.png Spiny or pungent Spiculata With stiff, sharp points such as thistles
Apex (tip)[edit]
Image Term Latin Description
Handdrawn Acuminate.png Acuminate _ Long-pointed, prolonged into a narrow, tapering point in a concave manner
Handdrawn Acute.png Acute _ Ending in a sharp, but not prolonged point
Handdrawn Cuspidate.png Cuspidate _ With a sharp, elongated, rigid tip; tipped with a cusp
Handdrawn Emarginate.png Emarginate _ Indented, with a shallow notch at the tip
Handdrawn Mucronate.png Mucronate _ Abruptly tipped with a small short point
Handdrawn Mucronate.png Mucronulate _ Mucronate, but with a noticeably diminutive spine
Handdrawn Obcordate.png Obcordate _ Inversely heart-shaped
Handdrawn Obtuse.png Obtuse _ Rounded or blunt
Handdrawn Truncate.png Truncate _ Ending abruptly with a flat end
Base[edit]
Acuminate
Coming to a sharp, narrow, prolonged point.
Acute
Coming to a sharp, but not prolonged point.
Auriculate
Ear-shaped.
Cordate
Heart-shaped with the notch towards the stalk.
Cuneate
Wedge-shaped.
Hastate
Shaped like an halberd and with the basal lobes pointing outward.
Oblique
Slanting.
Reniform
Kidney-shaped but rounder and broader than long.
Rounded
Curving shape.
Sagittate
Shaped like an arrowhead and with the acute basal lobes pointing downward.
Truncate
Ending abruptly with a flat end, that looks cut off.
Surface[edit]
The leaf surface is also host to a large variety of microorganisms; in this context it is referred to as the phyllosphere.
Hairiness[edit]
Scanning electron microscope image of trichomes on the lower surface of a Coleus blumei (coleus) leaf
“Hairs” on plants are properly called trichomes. Leaves can show several degrees of hairiness. The meaning of several of the following terms can overlap.
Arachnoid, or arachnose
With many fine, entangled hairs giving a cobwebby appearance.
Barbellate
With finely barbed hairs (barbellae).
Bearded
With long, stiff hairs.
Bristly
With stiff hair-like prickles.
Canescent
Hoary with dense grayish-white pubescence.
Ciliate
Marginally fringed with short hairs (cilia).
Ciliolate
Minutely ciliate.
Floccose
With flocks of soft, woolly hairs, which tend to rub off.
Glabrescent
Losing hairs with age.
Glabrous
No hairs of any kind present.
Glandular
With a gland at the tip of the hair.
Hirsute
With rather rough or stiff hairs.
Hispid
With rigid, bristly hairs.
Hispidulous
Minutely hispid.
Hoary
With a fine, close grayish-white pubescence.
Lanate, or lanose
With woolly hairs.
Pilose
With soft, clearly separated hairs.
Puberulent, or puberulous
With fine, minute hairs.
Pubescent
With soft, short and erect hairs.
Scabrous, or scabrid
Rough to the touch.
Sericeous
Silky appearance through fine, straight and appressed (lying close and flat) hairs.
Silky
With adpressed, soft and straight pubescence.
Stellate, or stelliform
With star-shaped hairs.
Strigose
With appressed, sharp, straight and stiff hairs.
Tomentose
Densely pubescent with matted, soft white woolly hairs.
Cano-tomentose
Between canescent and tomentose.
Felted-tomentose
Woolly and matted with curly hairs.
Tomentulose
Minutely or only slightly tomentose.
Villous
With long and soft hairs, usually curved.
Woolly
With long, soft and tortuous or matted hairs.
Timing[edit]
Hysteranthous
Developing after the flowers [44]
Synanthous
Developing at the same time as the flowers [45]
Venation[edit]
Classification[edit]
- Parallel venation, Iris
A number of different classification systems of the patterns of leaf veins (venation or veination) have been described,[25] starting with Ettingshausen (1861),[46] together with many different descriptive terms, and the terminology has been described as “formidable”.[25] One of the commonest among these is the Hickey system, originally developed for “dicotyledons” and using a number of Ettingshausen’s terms derived from Greek (1973–1979):[47][48][49] (see also: Simpson Figure 9.12, p. 468)[25]
Hickey system[edit]
- Pinnate (feather-veined, reticulate, pinnate-netted, penniribbed, penninerved, or penniveined)
The veins arise pinnately (feather like) from a single primary vein (mid-vein) and subdivide into secondary veinlets, known as higher order veins. These, in turn, form a complicated network. This type of venation is typical for (but by no means limited to) “dicotyledons” (non monocotyledon angiosperms). E.g., Ostrya. There are three subtypes of pinnate venation:
Craspedodromous (Greek: kraspedon – edge, dromos – running)
The major veins reach to the margin of the leaf.
Camptodromous
Major veins extend close to the margin, but bend before they intersect with the margin.
Hyphodromous
All secondary veins are absent, rudimentary or concealed
These in turn have a number of further subtypes such as eucamptodromous, where secondary veins curve near the margin without joining adjacent secondary veins.
Craspedodromous
Camptodromous
Hyphodromous
- Parallelodromous (parallel-veined, parallel-ribbed, parallel-nerved, penniparallel, striate)
Two or more primary veins originating beside each other at the leaf base, and running parallel to each other to the apex and then converging there. Commissural veins (small veins) connect the major parallel veins. Typical for most monocotyledons, such as grasses. The additional terms marginal (primary veins reach the margin), and reticulate (primary veins do not reach the margin) are also used. - Campylodromous (campylos – curve)
Several primary veins or branches originating at or close to a single point and running in recurved arches, then converging at apex. E.g. Maianthemum . - Acrodromous
Two or more primary or well developed secondary veins in convergent arches towards apex, without basal recurvature as in Campylodromous. May be basal or suprabasal depending on origin, and perfect or imperfect depending on whether they reach to 2/3 of the way to the apex. E.g., Miconia (basal type), Endlicheria (suprabasal type).
Imperfect basal
Imperfect suprabasal
Perfect basal
Perfect suprabasal
- Actinodromous
Three or more primary veins diverging radially from a single point. E.g., Arcangelisia (basal type), Givotia (suprabasal type).
Imperfect marginal
Imperfect reticulate
- Palinactodromous
Primary veins with one or more points of secondary dichotomous branching beyond the primary divergence, either closely or more distantly spaced. E.g., Platanus.
Venation of a poinsettia (Euphorbia pulcherrima) leaf
Venation of a Poinsettia (Euphorbia pulcherrima) leaf.
Types 4–6 may similarly be subclassified as basal (primaries joined at the base of the blade) or suprabasal (diverging above the blade base), and perfect or imperfect, but also flabellate.
At about the same time, Melville (1976) described a system applicable to all Angiosperms and using Latin and English terminology.[50] Melville also had six divisions, based on the order in which veins develop.
Arbuscular (arbuscularis)
Branching repeatedly by regular dichotomy to give rise to a three dimensional bush-like structure consisting of linear segment (2 subclasses)
Flabellate (flabellatus)
Primary veins straight or only slightly curved, diverging from the base in a fan-like manner (4 subclasses)
Palmate (palmatus)
Curved primary veins (3 subclasses)
Pinnate (pinnatus)
Single primary vein, the midrib, along which straight or arching secondary veins are arranged at more or less regular intervals (6 subclasses)
Collimate (collimatus)
Numerous longitudinally parallel primary veins arising from a transverse meristem (5 subclasses)
Conglutinate (conglutinatus)
Derived from fused pinnate leaflets (3 subclasses)
A modified form of the Hickey system was later incorporated into the Smithsonian classification (1999) which proposed seven main types of venation, based on the architecture of the primary veins, adding Flabellate as an additional main type. Further classification was then made on the basis of secondary veins, with 12 further types, such as;
Brochidodromous
Closed form in which the secondaries are joined together in a series of prominent arches, as in Hildegardia.
Craspedodromous
Open form with secondaries terminating at the margin, in toothed leaves, as in Celtis.
Eucamptodromous
Intermediate form with upturned secondaries that gradually diminish apically but inside the margin, and connected by intermediate tertiary veins rather than loops between secondaries, as in Cornus.
Cladodromous
Secondaries freely branching toward the margin, as in Rhus.
terms which had been used as subtypes in the original Hickey system.[51]
Brochidodromous
Craspedodromous
Eucamptodromous
Cladodromous
Further descriptions included the higher order, or minor veins and the patterns of areoles (see Leaf Architecture Working Group, Figures 28–29).[51]
Flabellate
Several to many equal fine basal veins diverging radially at low angles and branching apically. E.g. Paranomus.
Analyses of vein patterns often fall into consideration of the vein orders, primary vein type, secondary vein type (major veins), and minor vein density. A number of authors have adopted simplified versions of these schemes.[52][25] At its simplest the primary vein types can be considered in three or four groups depending on the plant divisions being considered;
pinnate
palmate
parallel
where palmate refers to multiple primary veins that radiate from the petiole, as opposed to branching from the central main vein in the pinnate form, and encompasses both of Hickey types 4 and 5, which are preserved as subtypes; e.g., palmate-acrodromous (see National Park Service Leaf Guide).[53]
Palmate, Palmate-netted, palmate-veined, fan-veined
Several main veins of approximately equal size diverge from a common point near the leaf base where the petiole attaches, and radiate toward the edge of the leaf. Palmately veined leaves are often lobed or divided with lobes radiating from the common point. They may vary in the number of primary veins (3 or more), but always radiate from a common point.[54] e.g. most Acer (maples).
Other systems[edit]
Alternatively, Simpson uses:[25]
Uninervous
Central midrib with no lateral veins (microphyllous), seen in the non-seed bearing tracheophytes, such as horsetails
Dichotomous
Veins successively branching into equally sized veins from a common point, forming a Y junction, fanning out. Amongst temperate woody plants, Ginkgo biloba is the only species exhibiting dichotomous venation. Also some pteridophytes (ferns).[54]
Parallel
Primary and secondary veins roughly parallel to each other, running the length of the leaf, often connected by short perpendicular links, rather than form networks. In some species, the parallel veins join together at the base and apex, such as needle-type evergreens and grasses. Characteristic of monocotyledons, but exceptions include Arisaema, and as below, under netted.[54]
Netted (reticulate, pinnate)
A prominent midvein with secondary veins branching off along both sides of it. The name derives from the ultimate veinlets which form an interconnecting net like pattern or network. (The primary and secondary venation may be referred to as pinnate, while the net like finer veins are referred to as netted or reticulate); most non-monocot angiosperms, exceptions including Calophyllum. Some monocots have reticulate venation, including Colocasia, Dioscorea and Smilax.[54]
Equisetum:
Reduced microphyllous leaves (L) arising in whorl from node
However, these simplified systems allow for further division into multiple subtypes. Simpson,[25] (and others)[55] divides parallel and netted (and some use only these two terms for Angiosperms)[56] on the basis of the number of primary veins (costa) as follows;
Parallel
Penni-parallel (pinnate, pinnate parallel, unicostate parallel)
Single central prominent midrib, secondary veins from this arise perpendicularly to it and run parallel to each other towards the margin or tip, but do not join (anastomose). The term unicostate refers to the prominence of the single midrib (costa) running the length of the leaf from base to apex. e.g. Zingiberales, such as Bananas etc.
Palmate-parallel (multicostate parallel)
Several equally prominent primary veins arising from a single point at the base and running parallel towards tip or margin. The term multicostate refers to having more than one prominent main vein. e.g. “fan” (palmate) palms (Arecaceae)
Multicostate parallel convergent
Mid-veins converge at apex e.g. Bambusa arundinacea = B. bambos (Aracaceae), Eichornia
Multicostate parallel divergent
Mid-veins diverge more or less parallel towards the margin e.g. Borassus (Poaceae), fan palms
Netted (Reticulate)
Pinnately (veined, netted, unicostate reticulate)
Single prominent midrib running from base to apex, secondary veins arising on both sides along the length of the primary midrib, running towards the margin or apex (tip), with a network of smaller veinlets forming a reticulum (mesh or network). e.g. Mangifera, Ficus religiosa, Psidium guajava, Hibiscus rosa-sinensis, Salix alba
Palmately (multicostate reticulate)
More than one primary veins arising from a single point, running from base to apex. e.g. Liquidambar styraciflua This may be further subdivided;
Multicostate convergent
Major veins diverge from origin at base then converge towards the tip. e.g. Zizyphus, Smilax, Cinnamomum
Multicostate divergent
All major veins diverge towards the tip. e.g. Gossypium, Cucurbita, Carica papaya, Ricinus communis
Ternately (ternate-netted)
Three primary veins, as above, e.g. (see) Ceanothus leucodermis,[57] C. tomentosus,[58] Encelia farinosa
Borassus sp.:
Multicostate parallel divergent
These complex systems are not used much in morphological descriptions of taxa, but have usefulness in plant identification, [25] although criticized as being unduly burdened with jargon.[59]
An older, even simpler system, used in some flora[60] uses only two categories, open and closed.[61]
Open: Higher order veins have free endings among the cells and are more characteristic of non-monocotyledon angiosperms. They are more likely to be associated with leaf shapes that are toothed, lobed or compound. They may be subdivided as;
Pinnate (feather-veined) leaves, with a main central vein or rib (midrib), from which the remainder of the vein system arises
Palmate, in which three or more main ribs rise together at the base of the leaf, and diverge upward.
Dichotomous, as in ferns, where the veins fork repeatedly
Closed: Higher order veins are connected in loops without ending freely among the cells. These tend to be in leaves with smooth outlines, and are characteristic of monocotyledons.
They may be subdivided into whether the veins run parallel, as in grasses, or have other patterns.
Other descriptive terms[edit]
There are also many other descriptive terms, often with very specialized usage and confined to specific taxonomic groups.[62] The conspicuousness of veins depends on a number of features. These include the width of the veins, their prominence in relation to the lamina surface and the degree of opacity of the surface, which may hide finer veins. In this regard, veins are called obscure and the order of veins that are obscured and whether upper, lower or both surfaces, further specified.[63][54]
Terms that describe vein prominence include bullate, channelled, flat, guttered, impressed, prominent and recessed (Fig. 6.1 Hawthorne & Lawrence 2013).[59][64] Veins may show different types of prominence in different areas of the leaf. For instance Pimenta racemosa has a channelled midrib on the upper surfae, but this is prominent on the lower surface.[59]
Describing vein prominence:
Bullate
Surface of leaf raised in a series of domes between the veins on the upper surface, and therefore also with marked depressions. e.g. Rytigynia pauciflora,[65] Vitis vinifera
Channelled (canalicululate)
Veins sunken below the surface, resulting in a rounded channel. Sometimes confused with “guttered” because the channels may function as gutters for rain to run off and allow drying, as in many Melastomataceae.[66] e.g. (see) Pimenta racemosa (Myrtaceae),[67] Clidemia hirta (Melastomataceae).
Guttered
Veins partly prominent, the crest above the leaf lamina surface, but with channels running along each side, like gutters
Impressed
Vein forming raised line or ridge which lies below the plane of the surface which bears it, as if pressed into it, and are often exposed on the lower surface. Tissue near the veins often appears to pucker, giving them a sunken or embossed appearance
Obscure
Veins not visible, or not at all clear; if unspecified, then not visible with the naked eye. e.g. Berberis gagnepainii. In this Berberis, the veins are only obscure on the undersurface.[68]
Prominent
Vein raised above surrounding surface so to be easily felt when stroked with finger. e.g. (see) Pimenta racemosa,[67] Spathiphyllum cannifolium[69]
Recessed
Vein is sunk below the surface, more prominent than surrounding tissues but more sunken in channel than with impressed veins. e.g. Viburnum plicatum.
Describing other features:
Plinervy (plinerved)
More than one main vein (nerve) at the base. Lateral secondary veins branching from a point above the base of the leaf. Usually expressed as a suffix, as in 3-plinerved or triplinerved leaf. In a 3-plinerved (triplinerved) leaf three main veins branch above the base of the lamina (two secondary veins and the main vein) and run essentially parallel subsequently, as in Ceanothus and in Celtis. Similarly, a quintuplinerve (five-veined) leaf has four secondary veins and a main vein. A pattern with 3-7 veins is especially conspicuous in Melastomataceae. The term has also been used in Vaccinieae. The term has been used as synonymous with acrodromous, palmate-acrodromous or suprabasal acrodromous, and is thought to be too broadly defined.[70][70]
Scalariform
Veins arranged like the rungs of a ladder, particularly higher order veins
Submarginal
Veins running close to leaf margin
Trinerved
2 major basal nerves besides the midrib
Diagrams of venation patterns[edit]
Image Term Description
Leaf morphology arcuate.png Arcuate Secondary arching toward the apex
Leaf morphology dichotomous.png Dichotomous Veins splitting in two
Leaf morphology longitudinal.png Longitudinal All veins aligned mostly with the midvein
Leaf morphology parallel.png Parallel All veins parallel and not intersecting
Leaf morphology pinnate.png Pinnate Secondary veins borne from midrib
Leaf morphology reticulate.png Reticulate All veins branching repeatedly, net veined
Leaf morphology rotate.png Rotate Veins coming from the center of the leaf and radiating toward the edges
Leaf morphology cross venulate.png Transverse Tertiary veins running perpendicular to axis of main vein, connecting secondary veins
Size[edit]
The terms megaphyll, macrophyll, mesophyll, notophyll, microphyll, nanophyll and leptophyll are used to describe leaf sizes (in descending order), in a classification devised in 1934 by Christen C. Raunkiær and since modified by others.[71]
See also[edit]
References[edit]
^ Jump up to: a b Esau 2006.
^ Cutter 1969.
^ Haupt 1953.
^ Jump up to: a b Mauseth 2009.
^ James et al 1999.
^ Jump up to: a b c d e Stewart & Rothwell 1993.
^ Cooney-Sovetts & Sattler 1987.
^ Tsukaya 2013.
^ Feugier 2006.
^ Purcell 2016.
^ Willert et al 1992.
^ Bayer 1982.
^ Marloth 1913–1932.
^ Jump up to: a b c Simpson 2011, p. 356.
^ Krogh 2010.
^ James & Bell 2000.
^ Heywood et al 2007.
^ Simpson 2011, pp. 356–357.
^ Hallé 1977.
^ Jump up to: a b c Botany Illustrated: Introduction to Plants Major Groups Flowering Plant Families. Thomson Science. 1984. p. 21.
^ Rolland-Lagan et al 2009.
^ Jump up to: a b c Walls 2011.
^ Jump up to: a b c Dickison 2000.
^ Jump up to: a b Rudall 2007.
^ Jump up to: a b c d e f g h i Simpson 2011, Leaf venation pp. 465–468
^ Jump up to: a b c d Sack & Scoffoni 2013.
^ Jump up to: a b c Roth-Nebelsick et al 2001.
^ Ueno et al 2006.
^ Runions et al 2005.
^ Massey & Murphy 1996, Surface-Venation-Texure
^ Bagchi et al 2016.
^ Cote 2009.
^ Clements 1905.
^ Couder et al 2002.
^ Corson et al 2009.
^ Laguna et al 2008.
^ Arber 1950.
^ Rutishauser & Sattler 1997.
^ Lacroix et al 2003.
^ Eckardt & Baum 2010.
^ Jump up to: a b c d e Read & Stokes 2006.
^ Doring et al 2009.
^ Feild et al 2001.
^ Kew Glossary: Hysteranthous
^ Kew Glossary: Synanthous
^ Ettingshausen 1861.
^ Hickey 1973.
^ Hickey & Wolfe 1975.
^ Hickey 1979.
^ Melville 1976.
^ Jump up to: a b Leaf Architecture Working Group 1999.
^ Judd et al 2007.
^ Florissant Leaf Key 2016.
^ Jump up to: a b c d e Kling et al 2005, Leaf Venation
^ Berg 2007.
^ Angiosperm Morphology 2017, Venation
^ Simpson 2017, Ceanothus leucodermis
^ Simpson 2017, Ceanothus tomentosus
^ Jump up to: a b c Hawthorne & Lawrence 2013, Leaf venation pp. 135–136
^ Cullen et al 2011.
^ Beach 1914, Venation
^ Neotropikey 2017.
^ Oxford herbaria glossary 2017.
^ Oxford herbaria glossary 2017, Vein prominence
^ Verdcourt & Bridson 1991.
^ Hemsley & Poole 2004, Leaf morphology and drying p. 254
^ Jump up to: a b Hughes 2017, Pimenta racemosa
^ Cullen et al 2011, Berberis gagnepainii vol. II p. 398
^ Kwantlen 2015, Spathiphyllum cannifolium
^ Jump up to: a b Pedraza-Peñalosa 2013.
^ Whitten et al 1997.
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Bagchi, Debjani; Dasgupta, Avik; Gondaliya, Amit D.; Rajput, Kishore S. (2016). “Insights from the Plant World: A Fractal Analysis Approach to Tune Mechanical Rigidity of Scaffolding Matrix in Thin Films”. Advanced Materials Research. 1141: 57–64. doi:10.4028/www.scientific.net/AMR.1141.57. S2CID 138338270.
Clements, Edith Schwartz (December 1905). “The Relation of Leaf Structure to Physical Factors”. Transactions of the American Microscopical Society. 26: 19–98. doi:10.2307/3220956. JSTOR 3220956.
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Corson, Francis; Adda-Bedia, Mokhtar; Boudaoud, Arezki (2009). “In silico leaf venation networks: Growth and reorganization driven by mechanical forces” (PDF). Journal of Theoretical Biology. 259 (3): 440–448. doi:10.1016/j.jtbi.2009.05.002. PMID 19446571. Archived from the original (PDF) on 2017-12-09.
Cote, G. G. (2009). “Diversity and distribution of idioblasts producing calcium oxalate crystals in Dieffenbachia seguine (Araceae)”. American Journal of Botany. 96 (7): 1245–1254. doi:10.3732/ajb.0800276. PMID 21628273.
Couder, Y.; Pauchard, L.; Allain, C.; Adda-Bedia, M.; Douady, S. (1 July 2002). “The leaf venation as formed in a tensorial field” (PDF). The European Physical Journal B. 28 (2): 135–138. Bibcode:2002EPJB…28..135C. doi:10.1140/epjb/e2002-00211-1. S2CID 51687210. Archived from the original (PDF) on 9 December 2017.
Döring, T. F; Archetti, M.; Hardie, J. (7 January 2009). “Autumn leaves seen through herbivore eyes”. Proceedings of the Royal Society B: Biological Sciences. 276 (1654): 121–127. doi:10.1098/rspb.2008.0858. PMC 2614250. PMID 18782744.
Eckardt, N. A.; Baum, D. (20 July 2010). “The Podostemad Puzzle: The Evolution of Unusual Morphology in the Podostemaceae”. The Plant Cell Online. 22 (7): 2104. doi:10.1105/tpc.110.220711. PMC 2929115. PMID 20647343.
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Websites[edit]
Bucksch, Alexander; Blonder, Benjamin; Price, Charles; Wing, Scott; Weitz, Joshua; Das, Abhiram (2017). “Cleared Leaf Image Database”. School of Biology, Georgia Institute of Technology. Retrieved 12 March 2017.
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Glossaries
Hughes, Colin. “The virtual field herbarium”. Oxford University Herbaria. Archived from the original on 5 March 2017. Retrieved 4 March 2017.
“Plant Characteristics”. Archived from the original (Glossary) on 5 March 2017. Retrieved 4 March 2017., in Hughes (2017)
“Glossary of botanical terms”. Neotropikey. Royal Botanic Gardens, Kew. Retrieved 18 February 2017.
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“Leafshapes”. Donsgarden. Retrieved 9 January 2020
.
External links
Look up leaf in Wiktionary, the free dictionary.
“Leaf”
Encyclopædia Britannica
(11th ed.)
1911
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💕💝💖💓🖤💙🖤💙🖤💙🖤❤️💚💛🧡❣️💞💔💘❣️🧡💛💚❤️🖤💜🖤💙🖤💙🖤💗💖💝💘
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*🌈✨ *TABLE OF CONTENTS* ✨🌷*
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🔥🔥🔥🔥🔥🔥*we won the war* 🔥🔥🔥🔥🔥🔥