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Encyclopedia > Foliage
The leaves of a Beech tree
A leaf with laminar structure and pinnate venation
A leaf with laminar structure and pinnate venation

In botany, a leaf is an above-ground plant organ specialized for photosynthesis. For this purpose, a leaf is typically flat (laminar) and thin, to expose the cells containing chloroplast (chlorenchyma tissue, a type of parenchyma) to light over a broad area, and to allow light to penetrate fully into the tissues. Leaves are also the sites in most plants where respiration, transpiration, and guttation take place. Leaves can store food and water, and are modified in some plants for other purposes. The comparable structures of ferns are correctly referred to as fronds. Furthermore, leaves are prominent in the human diet as leaf vegetables. Maple leaves in Brookfield, Massachusetts Autumn leaf color is a phenomenon that affects the normally green leaves of many deciduous trees by which they take on, during a few weeks in the autumn months, one or many colors that range from red to yellow. ... Image File history File links Leavessnipedale. ... Image File history File links Leavessnipedale. ... Species Fagus crenata - Japanese Beech Fagus engleriana - Chinese Beech Fagus grandifolia - American Beech Fagus hayatae - Taiwan Beech Fagus japonica - Japanese Blue Beech Fagus longipetiolata - South Chinese Beech Fagus lucida - Shining Beech Fagus mexicana - Mexican Beech or Haya Fagus orientalis - Oriental Beech Fagus sylvatica - European Beech Beech (Fagus) is a genus... Image File history File links Download high-resolution version (1024x768, 158 KB) Leaf1. ... Image File history File links Download high-resolution version (1024x768, 158 KB) Leaf1. ... Pinguicula grandiflora Botany is the scientific study of plantlife. ... Divisions Green algae Chlorophyta Charophyta Land plants (embryophytes) Non-vascular plants (bryophytes) Marchantiophyta—liverworts Anthocerotophyta—hornworts Bryophyta—mosses Vascular plants (tracheophytes) †Rhyniophyta—rhyniophytes †Zosterophyllophyta—zosterophylls Lycopodiophyta—clubmosses †Trimerophytophyta—trimerophytes Pteridophyta—ferns and horsetails Seed plants (spermatophytes) †Pteridospermatophyta—seed ferns Pinophyta—conifers Cycadophyta—cycads Ginkgophyta—ginkgo Gnetophyta—gnetae Magnoliophyta—flowering plants... In biology, an organ (Latin: organum, instrument, tool) is a group of tissues that perform a specific function or group of functions. ... The leaf is the primary site of photosynthesis in plants. ... Chloroplasts are organelles found in plant cells and eukaryotic algae that conduct photosynthesis. ... Parenchyma is a term used to describe a bulk of a substance. ... This article or section does not cite any references or sources. ... // In animal physiology, respiration is the transport of oxygen from the ambient air to the tissue cells and the transport of carbon dioxide in the opposite direction. ... Transpiration is the evaporation of water into the atmosphere from the leaves and stems of plants. ... Guttation is the appearance of drops of water on the leaves of some vascular plants, such as grasses. ... Impact from a water drop causes an upward rebound jet surrounded by circular capillary waves. ... Classes Psilotopsida Equisetopsida Marattiopsida Pteridopsida (Polypodiopsida) A fern is any one of a group of about 20,000 species of plants classified in the phylum or division Pteridophyta, also known as Filicophyta. ... A fern with simple (lobed or pinnatifid) blades, the dissection of each blade not quite reaching to the rachis. ... Trinomial name Homo sapiens sapiens Linnaeus, 1758 Humans, or human beings, are bipedal primates belonging to the mammalian species Homo sapiens (Latin: wise man or knowing man) in the family Hominidae (the great apes). ... In nutrition, the diet is the sum of food consumed by a person or other organism. ... Fresh Swiss chard Fresh water spinach Creamed spinach Steamed kale Leaf vegetables, also called potherbs, greens, or leafy greens, are plant leaves eaten as a vegetable, sometimes accompanied by tender petioles and shoots. ...

Contents

Leaf anatomy

A structurally complete leaf of an angiosperm consists of a petiole (leaf stem), a lamina (leaf blade), and stipules (small processes located to either side of the base of the petiole). The petiole attaches to the stem at a point that is called the "leaf axil". Not every species produces leaves with all of these structural components. In some species, paired stipules are not obvious or are absent altogether. A petiole may be absent, 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 Leaf morphology. After a period of time (i.e. seasonally, during the autumn), deciduous trees shed their leaves. These leaves decompose into the soil. It has been suggested that Angiospermae, and Anthophyta be merged into this article or section. ... Leaf of Dog Rose (Rosa canina), showing the petiole and two leafy stipules In botany, the petiole is the small stalk attaching the leaf blade to the stem. ... The lanceolate-linear, paired stipules of Hibiscus kokio In botany, stipule refers to outgrowths borne on either side of the base of a leafstalk (or petiole). ...


A leaf is considered to be a plant organ, typically consisting of the following tissues:

  1. An epidermis that covers the upper and lower surfaces
  2. An interior chlorenchyma called the mesophyll
  3. An arrangement of veins (the vascular tissue).

Image File history File links Leaf_anatomy. ...

Epidermis

The epidermis is the outer multi-layered group of cells covering the leaf. It forms the boundary separating the plant's inner cells from the external world. The epidermis serves several functions: protection against water loss, regulation of gas exchange, secretion of metabolic compounds, and (in some species) absorption of water. Most leaves show dorsoventral anatomy: the upper (adaxial) and lower (abaxial) surfaces have somewhat different construction and may serve different functions. The epidermis is the outer multi-layered group of cells covering the leaf and young tissues of a plant. ... Drawing of the structure of cork as it appeared under the microscope to Robert Hook from Micrographia which is the origin of the word cell. POOP Cells in culture, stained for keratin (red) and DNA (green). ... A few of the metabolic pathways in a cell. ...


The epidermis is usually transparent (epidermal cells lack chloroplasts) and coated on the outer side with a waxy cuticle that prevents water loss. The cuticle is in some cases thinner on the lower epidermis than on the upper epidermis, and is thicker on leaves from dry climates as compared with those from wet climates. Transparent glass ball In optics, transparency is the property of allowing light to pass. ... Plant cuticles are a protective waxy covering produced only by the epidermal cells (Kolattukudy, 1996) of leaves, young shoots and all other aerial plant organs. ...


The epidermis tissue includes several differentiated cell types: epidermal cells, guard cells, subsidiary cells, and epidermal hairs (trichomes). The epidermal cells are the most numerous, largest, and least specialized. These are typically more elongated in the leaves of monocots than in those of dicots. Trichomes, from the Greek meaning growth of hair, are fine outgrowths or appendages on plants and protists. ... Orders Base Monocots: Acorus Alismatales Asparagales Dioscoreales Liliales Pandanales Family Petrosaviaceae Commelinids: Arecales Commelinales Poales Zingiberales Family Dasypogonaceae Monocotyledons or monocots are a group of flowering plants usually ranked as a class and once called the Monocotyledoneae. ... Orders see text Dicotyledons or dicots are flowering plants whose seed contains two embryonic leaves or cotyledons. ...


The epidermis is covered with pores called stomata, part of a stoma complex consisting of a pore surrounded on each side by chloroplast-containing guard cells, and two to four subsidiary cells that lack chloroplasts. The stoma complex regulates the exchange of gases and water vapor between the outside air and the interior of the leaf. Typically, the stomata are more numerous over the abaxial (lower) epidermis than the adaxial (upper) epidermis. Stoma of a leaf under a microscope. ...


Mesophyll

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". Parenchyma is a term used to describe a bulk of a substance. ... Chlorenchyma cells in plant anatomy are parenchyma cells that contain chloroplasts. ... This article is about the leaf, a plant organ. ... This article or section is in need of attention from an expert on the subject. ...


In ferns and most flowering plants the mesophyll is divided into two layers:

  • An upper palisade layer of tightly packed, vertically elongated cells, one to two cells thick, directly beneath the adaxial epidermis. Its cells contain many more chloroplasts than the spongy layer. These long cylindrical cells are regularly arranged in one to five rows. 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. This separation must be minimal to afford capillary action for water distribution. In order to adapt to their different environment (such as sun or shade), plants had to adapt this structure to obtain optimal result. 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 rounded and not so tightly packed. There are large intercellular air spaces. These cells contain fewer chloroplasts than those of the palisade layer.

The pores or stomata of the epidermis open into substomatal chambers, connecting to air spaces between the spongy layer cells. This article or section does not cite its references or sources. ... Absorption, in chemistry, is a physical or chemical phenomenon or a process in which atoms, molecules, or ions enter some bulk phase - gas, liquid or solid material. ... Capillary action, capillarity, or capillary motion is the ability of a substance (the standard reference is to a tube in plants but can be seen readily with porous paper) to draw a substance up against gravity. ...


These two different layers of the mesophyll are absent in many aquatic and marsh plants. Even an epidermis and a mesophyll may be lacking. Instead for their gaseous exchanges they use a homogeneous aerenchyma (thin-walled cells separated by large gas-filled spaces). Their stomata are situated at the upper surface. Aerenchyma is the spongy tissue occurring mainly in the stems of many aquatic or marsh plants. ...


Leaves are normally green in color, which comes from chlorophyll found in plastids in the chlorenchyma cells. Plants that lack chlorophyll cannot photosynthesize. Mossy, green fountain in Wattens, Austria. ... Chlorophyll gives leaves their green color Space-filling model of the chlorophyll molecule Chlorophyll is a green photosynthetic pigment found in most plants, algae, and cyanobacteria. ... Plastids are major organelles found in plants and algae. ... The leaf is the primary site of photosynthesis in plants. ...

Fallen autumn leaves
Fallen autumn leaves

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. After the leaf is shed, a leaf scar develops on the twig. In cold autumns they sometimes change color, and turn yellow, bright orange or red as various accessory pigments (carotenoids and anthocyanins) are revealed when the tree responds to cold and reduced sunlight by curtailing chlorophyll production. Image File history File links Download high resolution version (1600x1067, 349 KB) Please see the file description page for further information. ... Image File history File links Download high resolution version (1600x1067, 349 KB) Please see the file description page for further information. ... In geography, temperate latitudes of the globe lie between the tropics and the polar circles. ... Boreal may refer to these: Northern from the eponymous Boreas, god of the North Wind in Greek mythology. ... Deciduous means temporary or tending to fall off (deriving from the Latin word decidere, to fall off) and is typically used in reference to trees or shrubs that lose their leaves seasonally. ... Abscission (from ab- away from, and scission cutting or severing) is the shedding of a body part. ... Maple leaves in Brookfield, Massachusetts Autumn leaf color is a phenomenon that affects the normally green leaves of many deciduous trees by which they take on, during a few weeks in the autumn months, one or many colors that range from red to yellow. ... A yellow Tulip. ... The orange, a fruit from which the modern name of the orange colour comes. ... Red is any of a number of similar colors evoked by light consisting predominantly of the longest wavelengths of light discernible by the human eye, in the wavelength range of roughly 625–750 nm. ... The orange ring surrounding Grand Prismatic Spring is due to carotenoid molecules, produced by huge mats of algae and bacteria. ... Plants with abnormally high anthocyanin quantities are popular as ornamental plants - here, a selected purple-leaf cultivar of European Beech Anthocyanins (from Greek: (anthos) = flower + (kyanos) = blue) are water-soluble vacuolar flavonoid pigments that appear red to blue, according to pH. They are synthesized exclusively by organisms of the plant... Prism splitting light High Resolution Solar Spectrum Sunlight in the broad sense is the total spectrum of the electromagnetic radiation given off by the Sun. ...


Veins

The veins are the vascular tissue of the leaf and are located in the spongy layer of the mesophyll. They are typical examples of pattern formation through ramification. The pattern of the veins is called venation. Cross section of celery stalk, showing vascular bundles, which include both phloem and xylem. ... The science of pattern formation deals with the visible, (statistically) orderly outcomes of self-organisation and the common principles behind similar patterns. ... Naturally-occurring ramification helps gives these conifers a regular, cone-shaped outline. ... The arrangements of veins and veinlets is called venation. ...


The veins are made up of:

  • xylem, which brings water from the roots into the leaf.
  • phloem, which usually moves sap out, the latter containing the glucose produced by photosynthesis in the leaf.

The xylem typically lies over the phloem. Both are embedded in a dense parenchyma tissue, called "pith", with usually some structural collenchyma tissue present. In vascular plants, xylem is one of the two types of transport tissue in plants, phloem being the other one. ... In vascular plants, phloem is the living tissue that carries organic nutrients, particularly sucrose, a sugar, to all parts of the plant where needed. ...


Leaf morphology

Underside view of a leaf

External leaf characteristics (such as shape, margin, hairs, etc.) are important for identifying plant species, and botanists have developed a rich terminology for describing leaf characteristics. These structures are a part of what makes leaves determinant, they grow and achieve a specific pattern and shape, then stop. Other plant parts like stems or roots are non-determinant, and will usually continue to grow as long as they have the resources to do so. Leaf photo close-up, shot on a Nikon digital camera by Nicholas Moreau (user:zanimum) This image has been released into the public domain by the copyright holder, its copyright has expired, or it is ineligible for copyright. ... Leaf photo close-up, shot on a Nikon digital camera by Nicholas Moreau (user:zanimum) This image has been released into the public domain by the copyright holder, its copyright has expired, or it is ineligible for copyright. ... In biology, a species is one of the basic units of biodiversity. ... Terminology is the study of terms and their use — of words and compound words that are used in specific contexts. ...


Classification of leaves can occur through many different designative schema, and the type of leaf is usually characteristic of a species, although some species produce more than one type of leaf. The longest type of leaf is a leaf from palm trees, measuring at nine feet long. The terminology associated with the description of leaf morphology is presented, in illustrated form, at Wikibooks.


Basic leaf types

Leaves of the White Spruce (Picea glauca) are needle-shaped and their arrangement is spiral
Leaves of the White Spruce (Picea glauca) are needle-shaped and their arrangement is spiral

Image File history File links Download high-resolution version (1024x1280, 205 KB) File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Leaf Gymnosperm ... Image File history File links Download high-resolution version (1024x1280, 205 KB) File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Leaf Gymnosperm ... Classes Psilotopsida Equisetopsida Marattiopsida Pteridopsida (Polypodiopsida) A fern is any one of a group of about 20,000 species of plants classified in the phylum or division Pteridophyta, also known as Filicophyta. ... A fern with simple (lobed or pinnatifid) blades, the dissection of each blade not quite reaching to the rachis. ... Orders & Families Cordaitales † Pinales   Pinaceae - Pine family   Araucariaceae - Araucaria family   Podocarpaceae - Yellow-wood family   Sciadopityaceae - Umbrella-pine family   Cupressaceae - Cypress family   Cephalotaxaceae - Plum-yew family   Taxaceae - Yew family Vojnovskyales † Voltziales † The conifers, division Pinophyta, are one of 13 or 14 division level taxa within the Kingdom Plantae. ... It has been suggested that Angiospermae, and Anthophyta be merged into this article or section. ... Classes Lycopodiopsida - clubmosses Selaginellopsida - spikemosses Isoetopsida - quillworts The Division Lycopodiophyta (sometimes called Lycophyta) is a tracheophyte subdivision of the Kingdom Plantae. ... Microphylls are photosynthetic flaps of plant tissue with a solitary, unbranched vein. ... The word sheath has a number of related meanings in English. ... Subfamilies There are 7 subfamilies: Subfamily Arundinoideae Subfamily Bambusoideae Subfamily Centothecoideae Subfamily Chloridoideae Subfamily Panicoideae Subfamily Pooideae Subfamily Stipoideae The true grasses are monocotyledonous plants (Class Liliopsida) in the Family Poaceae, also known as Gramineae. ... Species See text The genus Nepenthes (Tropical Pitcher Plants or Monkey Cups) in the monotypic family Nepenthaceae contains roughly 80-100 species, (depending on author), several natural and many cultivated hybrids. ...

Arrangement on the stem

Different terms are usually used to describe leaf placement (phyllotaxis): In botany, phyllotaxis is the arrangement of the leaves on the shoot of a plant. ...

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 developing buds in the axils of these leaves.
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 developing buds in the axils of these leaves.
  • Alternate — leaf attachments are singular at nodes, and leaves alternate direction, to a greater or lesser degree, along the stem.
  • Opposite — leaf attachments are paired at each node; decussate if, as typical, each successive pair is rotated 90° progressing along the stem; or distichous if not rotated, but two-ranked (in the same geometric flat-plane) [1].
  • Whorled — three or more leaves 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.
  • Rosulate — leaves form a rosette

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 centred 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 a limit of 360° x 34/89 = 137.52 or 137° 30', an angle known mathematically as the golden angle. In the series, the numerator indicates the number of complete turns or "gyres" until a leaf arrives at the initial position. The denominator indicates the number of leaves in the arrangement. This can be demonstrated by the following: Download high resolution version (950x683, 185 KB)Photo of plant (Alternanthera sp. ... Download high resolution version (950x683, 185 KB)Photo of plant (Alternanthera sp. ... A rosette of leaves at the base of a dandelion In botany, a rosette is a circular arrangement of the leaves, with all the leaves at a single height. ... A helix (pl: helices), from the Greek word έλικας/έλιξ, is a twisted shape like a spring, screw or a spiral (correctly termed helical) staircase. ... A clockwise motion is one that proceeds like the clocks hands: from the top to the right, then down and then to the left, and back to the top. ... In mathematics, the Fibonacci numbers form a sequence defined recursively by: In words: you start with 0 and 1, and then produce the next Fibonacci number by adding the two previous Fibonacci numbers. ... In geometry, the golden angle is the angle created by dividing the circumference c of a circle into a section a and a smaller section b such that and and taking the angle of arc subtended by the length of circumference equal to b as the golden angle. ... In algebra, a vulgar fraction consists of one integer divided by a non-zero integer. ...

  • 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.

The fact that an arrangement of anything in nature can be described by a mathematical formula is not in itself mysterious. Mathematics are the science of discovering numerical relationships and applying formulae to these relationships. The formulae themselves can provide clues to the underlying physiological processes that, in this case, determine where the next leaf bud will form in the elongating stem. Euclid, Greek mathematician, 3rd century BC, as imagined by by Raphael in this detail from The School of Athens. ... A formula is a concise way of expressing information symbolically (as in a mathematical or chemical formula) or a general relationship between quantities. ...


Divisions of the lamina (blade)

Two basic forms of leaves can be described considering the way the blade is divided. A simple leaf has an undivided blade. However, the leaf shape may be formed of 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 separated along a main or secondary vein. 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. A leaflet in botany is a part of a compound leaf. ... Subfamilies Faboideae Caesalpinioideae Mimosoideae References GRIN-CA 2002-09-01 The name Fabaceae belongs to either of two families, depending on viewpoint. ... A fern with simple (lobed or pinnatifid) blades, the dissection of each blade not quite reaching to the rachis. ... Rachis was also king of the Lombards, 744-749. ...

  • Palmately compound leaves have the leaflets radiating from the end of the petiole, like fingers off the palm of a hand, e.g. Cannabis (hemp) and Aesculus (buckeyes).
  • Pinnately compound leaves have the leaflets arranged along the main or mid-vein.
    • odd pinnate: with a terminal leaflet, e.g. Fraxinus (ash).
    • even pinnate: lacking a terminal leaflet, e.g. Swietenia (mahogany).
  • 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 pinnules on one secondary vein are called "pinna"; e.g. Albizia (silk tree).
  • trifoliate: a pinnate leaf with just three leaflets, e.g. Trifolium (clover), Laburnum (laburnum).
  • pinnatifid: pinnately dissected to the midrib, but with the leaflets not entirely separate, e.g. Polypodium, some Sorbus (whitebeams).

Look up Cannabis in Wiktionary, the free dictionary. ... Species Aesculus arguta: Texas Buckeye Aesculus californica: California Buckeye Aesculus chinensis: Chinese Horse-chestnut Aesculus flava (): Yellow Buckeye Aesculus glabra: Ohio Buckeye Aesculus hippocastanum: Common Horse-chestnut Aesculus indica: Indian Horse-chestnut Aesculus neglecta: Dwarf Buckeye Aesculus parviflora: Bottlebrush Buckeye Aesculus pavia: Red Buckeye Aesculus sylvatica: Painted Buckeye Aesculus turbinata... Species See text European Ash in flower Narrow-leafed Ash (Fraxinus angustifolia) shoot with leaves Closeup of European Ash seeds 19th century illustration of Manna Ash (Fraxinus ornus) An ash can be any of four different tree genera from four very distinct families (see end of page for disambiguation), but... An example of Mahogany The name mahogany is used when referring to numerous varieties of dark-colored wood, originally the wood of the species Swietenia mahagoni, sometimes referred to as Spanish or Cuban Mahogany. ... Species About 150 species Albizia is a genus of about 150 species of mostly fast-growing subtropical and tropical trees and shrubs in the Subfamily Mimosoideae of the legume family, Fabaceae. ... Species See text Clover is my sisters name! Clover (Trifolium) is a genus of about 300 species of plants in the pea family Fabaceae. ... Species Laburnum anagyroides Laburnum alpinum Laburnum is a genus of two species of small trees in the subfamily Faboideae of the pea family Fabaceae, Laburnum anagyroides (Common Laburnum) and (Alpine Laburnum). ... Species See text Polypodium is a large genus of true ferns, widely distributed throughout the world, but specially developed in the tropics. ... Subgenera Sorbus Aria Micromeles Cormus Torminaria Chamaemespilus The genus Sorbus is a genus of about 100-200 species of trees and shrubs in the subfamily Maloideae of the Rose family Rosaceae. ...

Characteristics of the petiole

The overgrown petioles of Rhubarb (Rheum rhabarbarum) are edible.
The overgrown petioles of Rhubarb (Rheum rhabarbarum) are edible.

Petiolated leaves have a petiole. Sessile leaves do not: the blade attaches directly to the stem. In clasping or decurrent leaves, the blade partially or wholly surrounds the stem, often giving the impression that the shoot grows through the leaf. When this is actually the case, the leaves are called "perfoliate", such as in Claytonia perfoliata. In peltate leaves, the petiole attaches to the blade inside from the blade margin. Image File history File links Rabarber_stelen. ... Image File history File links Rabarber_stelen. ... Species About 60, including: R. nobile R. palmatum For other uses see Rhubarb (disambiguation) Rhubarb is a perennial plant that grows from thick short rhizomes, comprising the genus Rheum. ... Leaf of Dog Rose (Rosa canina), showing the petiole and two leafy stipules In botany, the petiole is the small stalk attaching the leaf blade to the stem. ... Binomial name Claytonia perfoliata Donn ex Willd. ...


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. Species About 1,300; see List of Acacia species Acacia tree in the Serengeti, Tanzania Acacia is a genus of shrubs and trees of Gondwanian origin belonging to the subfamily Mimosoideae of the family Fabaceae, first described from Africa by Linnaeus in 1773. ... A young Koa tree showing compound leaves and phyllodes The Koa (Acacia koa; Family Fabaceae) is a large tree endemic to the Australian and Pacific islands acacias) in that the leaves produced early in the growth of the plant are compound leaves typical of the pea family. ... Phyllodes are modified petioles or leaf stems. ...


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 lanceolate-linear, paired stipules of Hibiscus kokio In botany, stipule refers to outgrowths borne on either side of the base of a leafstalk (or petiole). ... Orders See text. ... Species Between 100 and 150, see list Wikimedia Commons has media related to: Rosa A rose is a flowering shrub of the genus Rosa, and the flower of this shrub. ... Green beans Bean is a common name for large plant seeds of several genera of Fabaceae (formerly Leguminosae) used for food or feed. ...

  • The situation, arrangement, and structure of the stipules is called the "stipulation".
    • free
    • adnate : fused to the petiole base
    • ochreate : provided with ochrea, or sheath-formed stipules, e.g. rhubarb,
    • encircling the petiole base
    • interpetiolar : between the petioles of two opposite leaves.
    • intrapetiolar : between the petiole and the subtending stem

In botany, stipule (Latin stipula: straw, stalk[1]) is a term coined by Linnaeus[1] which refers to outgrowths borne on either side of the base of a leafstalk (the petiole). ... Species About 60, including: R. nobile R. palmatum For other uses see Rhubarb (disambiguation) Rhubarb is a perennial plant that grows from thick short rhizomes, comprising the genus Rheum. ...

Venation (arrangement of the veins)

Palmate-veined leaf
Palmate-veined leaf
Vein skeleton of a Hydrangea leaf

There are two subtypes of venation, namely, craspedodromous, where the major veins stretch up to the margin of the leaf, and camptodromous, when major veins extend close to the margin, but bend before they intersect with the margin. Palmate-veined leaf File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... Palmate-veined leaf File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... Image File history File linksMetadata Download high-resolution version (800x700, 144 KB)HELLO File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... Image File history File linksMetadata Download high-resolution version (800x700, 144 KB)HELLO File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... Species See text Hydrangea (common name also Hydrangea; pronounced haidréindʒiə) is a genus of about 70-75 species of flowering plants native to southern and eastern Asia (from Japan to China, the Himalaya and Indonesia) and North and South America. ...

  • Feather-veined, reticulate — the veins arise pinnately from a single mid-vein and subdivide into veinlets. These, in turn, form a complicated network. This type of venation is typical for dicotyledons.
    • Pinnate-netted, penniribbed, penninerved, penniveined; the leaf has usually one main vein (called the mid-vein), with veinlets, smaller veins branching off laterally, usually somewhat parallel to each other; eg Malus (apples).
    • Three main veins originate from the base of the lamina, as in Ceanothus.
    • Palmate-netted, palmate-veined, fan-veined; several main veins diverge from near the leaf base where the petiole attaches, and radiate toward the edge of the leaf; e.g. most Acer (maples).
  • Parallel-veined, parallel-ribbed, parallel-nerved, penniparallel — veins run parallel most the length of the leaf, from the base to the apex. Commissural veins (small veins) connect the major parallel veins. Typical for most monocotyledons, such as grasses.
  • Dichotomous — There are no dominant bundles, with the veins forking regularly by pairs; found in Ginkgo and some pteridophytes.

Orders See text. ... Species Malus angustifolia - Southern Crab Malus baccata - Siberian Crabapple Malus bracteata Malus brevipes Malus coronaria - Sweet Crabapple Malus domestica - Apple Malus florentina Malus floribunda - Japanese Crabapple Malus formosana Malus fusca - Oregon Crab, Pacific Crab Malus glabrata Malus glaucescens Malus halliana Malus honanensis Malus hupehensis - Chinese Crabapple Malus ioensis - Prairie Crab... Species See text Ceanothus L., is a genus of about 50-60 species of shrubs or small trees in the buckthorn family Rhamnaceae. ... In vector calculus, the divergence is an operator that measures a vector fields tendency to originate from or converge upon a given point. ... Distribution Species See List of Acer species Maples are trees or shrubs in the genus Acer. ... Parallel is a term in geometry and in everyday life that refers to a property in Euclidean space of two or more lines or planes, or a combination of these. ... Hemerocallis flower, with three flower parts in each whorl Wheat, an economically important monocot The monocotyledons or Monocots are a group of flowering plants, (angiosperms) dominating great parts of the earth. ... Subfamilies There are 7 subfamilies: Subfamily Arundinoideae Subfamily Bambusoideae Subfamily Centothecoideae Subfamily Chloridoideae Subfamily Panicoideae Subfamily Pooideae Subfamily Stipoideae The true grasses are monocotyledonous plants (Class Liliopsida) in the Family Poaceae, also known as Gramineae. ... Binomial name Ginkgo biloba L. The Ginkgo (Ginkgo biloba), frequently misspelled as Gingko, and sometimes known as the Maidenhair Tree, is a unique tree with no close living relatives. ... Classes Psilotopsida Equisetopsida Marattiopsida Pteridopsida (Polypodiopsida) A fern is any one of a group of about 20,000 species of plants classified in the phylum or division Pteridophyta, also known as Filicophyta. ...

Leaf morphology changes within a single plant

  • Homoblasty - Characteristic in which a plant has small changes in leaf size, shape, and growth habit between juvenile and adult stages.
  • Heteroblasty - Charactistic in which a plant has marked changes in leaf size, shape, and growth habit between juvenile and adult stages.



Leaf terminology

Stylized alternate maple leaf shape design found in Canada on flag and elsewhere
Chart illustrating some leaf morphology terms
Chart illustrating some leaf morphology terms
Shape
Main article: Leaf shape

Image File history File links Size of this preview: 600 × 600 pixelsFull resolution (610 × 610 pixel, file size: 5 KB, MIME type: image/gif) From http://www. ... Image File history File links Size of this preview: 600 × 600 pixelsFull resolution (610 × 610 pixel, file size: 5 KB, MIME type: image/gif) From http://www. ... Image File history File links Download high resolution version (2163x1977, 603 KB) Summary Chart of leaf morphology characteristics. ... Image File history File links Download high resolution version (2163x1977, 603 KB) Summary Chart of leaf morphology characteristics. ... In botany, the following terms are used to describe the shape of plant leaves: cordate leaf Acicular: slender and pointed Alternate (alternifolia): Arranged alternately Bipinnate (bipinnata): Each leaflet also pinnate Cordate (cordata): Heart-shaped, stem attaches to cleft Cuneate: Triangular, stem attaches to point Deltoid: Triangular, stem attaches to side...

Margins (edge)

The leaf margin is characteristic for a genus and aids in determining the species.

  • entire: even; with a smooth margin; without toothing
  • ciliate: fringed with hairs
  • crenate: wavy-toothed; dentate with rounded teeth, such as Fagus (beech)
  • dentate: toothed, such as Castanea (chestnut)
    • coarse-toothed: with large teeth
    • glandular toothed: with teeth that bear glands.
  • denticulate: finely toothed
  • doubly toothed: each tooth bearing smaller teeth, such as Ulmus (elm)
  • lobate: indented, with the indentations not reaching to the center, such as many Quercus (oaks)
    • palmately lobed: indented with the indentations reaching to the center, such as Humulus (hop).
  • serrate: saw-toothed with asymmetrical teeth pointing forward, such as Urtica (nettle)
  • serrulate: finely serrate
  • sinuate: with deep, wave-like indentations; coarsely crenate, such as many Rumex (docks)
  • spiny: with stiff, sharp points, such as some Ilex (hollies) and Cirsium (thistles).

Species Fagus crenata - Japanese Beech Fagus engleriana - Chinese Beech Fagus grandifolia - American Beech Fagus hayatae - Taiwan Beech Fagus japonica - Japanese Blue Beech Fagus longipetiolata - South Chinese Beech Fagus lucida - Shining Beech Fagus mexicana - Mexican Beech or Haya Fagus orientalis - Oriental Beech Fagus sylvatica - European Beech Beech (Fagus) is a genus... Species Castanea alnifolia - Bush Chinkapin* Castanea crenata - Japanese Chestnut Castanea dentata - American Chestnut Castanea henryi - Henrys Chestnut Castanea mollissima - Chinese Chestnut Castanea ozarkensis - Ozark Chinkapin Castanea pumila - Allegheny Chinkapin Castanea sativa - Sweet Chestnut Castanea seguinii - Seguins Chestnut * treated as a synonym of by many authors Chestnut (Castanea), including... Species See text. ... Species See List of Quercus species The term oak can be used as part of the common name of any of several hundred species of trees and shrubs in the genus Quercus, and some related genera, notably Cyclobalanopsis and Lithocarpus. ... Species Humulus lupulus L. Humulus japonicus Siebold & Zucc. ... Species See text. ... Species About 200, see text. ... Species Ilex ambigua—Sand Holly Ilex amelanchier—Swamp Holly Ilex aquifolium—European Holly Ilex bioritsensis Ilex buergeri Ilex canariensis—Small-leaved Holly Ilex cassine—Dahoon Holly Ilex centrochinensis Ilex ciliospinosa Ilex colchica Ilex collina Ilex corallina Ilex coriacea—Gallberry Ilex cornuta—Chinese Holly Ilex crenata—Japanese Holly Ilex cyrtura Ilex... Milk thistle flowerhead Thistledown a method of seed dispersal by wind. ...

Tip of the leaf

Leaves showing various morphologies. Clockwise from upper left: tripartite lobation, elliptic with serrulate margin, peltate with palmate venation, acuminate odd-pinnate (center), pinnatisect, lobed, elliptic with entire margin
Leaves showing various morphologies. Clockwise from upper left: tripartite lobation, elliptic with serrulate margin, peltate with palmate venation, acuminate odd-pinnate (center), pinnatisect, lobed, elliptic with entire margin
  • acuminate: long-pointed, prolonged into a narrow, tapering point in a concave manner.
  • acute: ending in a sharp, but not prolonged point
  • cuspidate: with a sharp, elongated, rigid tip; tipped with a cusp.
  • emarginate: indented, with a shallow notch at the tip.
  • mucronate: abruptly tipped with a small short point, as a continuation of the midrib; tipped with a mucro.
  • mucronulate: mucronate, but with a smaller spine.
  • obcordate: inversely heart-shaped, deeply notched at the top.
  • obtuse: rounded or blunt
  • truncate: ending abruptly with a flat end, that looks cut off.

Image File history File links Download high resolution version (847x1159, 108 KB) Summary leaves scanned by me, User debivort 1998. ... Image File history File links Download high resolution version (847x1159, 108 KB) Summary leaves scanned by me, User debivort 1998. ...

Base of the leaf

  • 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 norch away from the stem.
  • 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 of the leaf

The "Scale" shape leaves (needles) of the Norfolk Island Pine tree. Araucaria heterophylla
The "Scale" shape leaves (needles) of the Norfolk Island Pine tree. Araucaria heterophylla

The surface of a leaf can be described by several botanical terms: Image File history File linksMetadata Download high-resolution version (576x800, 412 KB) Close up of Norfolk Pine needles. ... Image File history File linksMetadata Download high-resolution version (576x800, 412 KB) Close up of Norfolk Pine needles. ... Binomial name Araucaria heterophylla (Salisb. ...

  • farinose: bearing farina; mealy, covered with a waxy, whitish powder.
  • glabrous: smooth, not hairy.
  • glaucous: with a whitish bloom; covered with a very fine, bluish-white powder.
  • glutinous: sticky, viscid.
  • papillate, papillose: bearing papillae (minute, nipple-shaped protuberances).
  • pubescent: covered with erect hairs (especially soft and short ones)
  • punctate: marked with dots; dotted with depressions or with translucent glands or colored dots.
  • rugose: deeply wrinkled; with veins clearly visible.
  • scurfy: covered with tiny, broad scalelike particles.
  • tuberculate: covered with tubercles; covered with warty prominences.
  • verrucose: warted, with warty outgrowths.
  • viscid, viscous: covered with thick, sticky secretions.

The leaf surface is also host to a large variety of microorganisms; in this context it is referred to as the phyllosphere. A microorganism or microbe is an organism that is so small that it is microscopic (invisible to the naked eye). ... The phyllosphere is a term used in microbiology to refer to leaf surfaces or total above-ground surfaces of a plant as a habitat for microorganisms. ...


Hairiness (trichomes)

Common Mullein (Verbascum thapsus) leaves are covered in dense, stellate trichomes.

"Hairs" on plants are properly called trichomes. Leaves can show several degrees of hairiness. The meaning of several of the following terms can overlap. Image File history File linksMetadata Download high-resolution version (1224x1632, 1060 KB) http://www. ... Image File history File linksMetadata Download high-resolution version (1224x1632, 1060 KB) http://www. ... Binomial name Verbascum thapsus L. Verbascum thapsus (Common or Great Mullein) is a species of mullein, native to Europe, northern Africa and Asia, and introduced in the Americas and Australia. ... Trichomes, from the Greek meaning growth of hair, are fine outgrowths or appendages on plants and protists. ...

  • glabrous: no hairs of any kind present.
  • arachnoid, 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.
  • 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, lanose: with woolly hairs.
  • pilose: with soft, clearly separated hairs.
  • puberulent, puberulous: with fine, minute hairs.
  • pubescent: with soft, short and erect hairs.
  • scabrous, 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, 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.
  • villous: with long and soft hairs, usually curved.
  • woolly: with long, soft and tortuous or matted hairs.

Adaptations

The leaves of Poinsettia have evolved a red pigmentation in order to attract insects and birds to the central flowers, an adaptive function normally served by petals.
The leaves of Poinsettia have evolved a red pigmentation in order to attract insects and birds to the central flowers, an adaptive function normally served by petals.

In the course of evolution, leaves adapted to different environments in the following ways: Image File history File linksMetadata Download high resolution version (2592x1944, 1232 KB) Summary Photo of Poinsettia, taken by Vineeth. ... Image File history File linksMetadata Download high resolution version (2592x1944, 1232 KB) Summary Photo of Poinsettia, taken by Vineeth. ... Binomial name Euphorbia pulcherrima Willd. ... It has been suggested that Corolla be merged into this article or section. ...

  • A certain surface structure avoids moistening by rain and contaminations (Lotus effect).
  • Sliced leaves reduce wind resistance.
  • Hairs on the leaf surface trap humidity in dry climates and creates a large boundary layer and reduces water loss.
  • Waxy leaf surfaces reduce water loss.
  • Shiny leaves deflect the sun's rays.
  • Reductions of leaf sizes accompanied by a transfer of the photosynthetic functions to the stems reduces water loss.
  • In more or less opaque or buried in the soil leaves translucent windows filter the light before the photosynthetis takes place at the inner leaf surfaces (e.g. Fenestraria).
  • Thicker leaves store water (leaf succulents).
  • Aromatic oils, poisons or pheromones produced by leaf borne glands deter herbivores (e.g. eucalypts).
  • Inclusions of crystalline minerals deters herbivores.
  • A transformation into petals attracts pollinators.
  • A transformation into spines protects the plants (e.g. cactus).
  • A transformation into insect traps helps feeding the plants (carnivorous plants).
  • A transformation into bulbs helps storing food and water (e.g. onion).
  • A transformation into tendrils allow the plant to climb (e.g. pea).
  • A transformation into bracts and pseudanthia (false flowers) replaces normal flower structures if the true flowers are extremely reduced (e.g. Spurges).

Water on the surface of a lotus leaf The Lotus effect in material science is the observed self-cleaning property found with lotus plants. ... candle wax This page is about the substance. ... The Sun (Latin: Sol) is the star at the center of the Solar System. ... Species Fenestraria rhopalophylla Fenestraria is a monotypic genus of succulent plants in the family Aizoaceae. ... Succulent plants, or succulents, are plants that store water in their enlarged fleshy leaves, stems, or roots. ... Fragrance oils, also known as aroma oils, aromatic oils, and flavor oils, are blended synthetic aroma compounds or natural essential oils that are diluted with a carrier like propylene glycol, vegetable oil, or mineral oil. ... This article is about the dangerous substance. ... Fanning honeybee exposes Nasonov gland (white-at tip of abdomen) releasing pheromone to entice swarm into an empty hive A pheromone is any chemical produced by a living organism that transmits a message to other members of the same species. ... Species About 600, see text Eucalyptus is a diverse genus of trees (rarely shrubs), the members of which dominate the tree flora of Australia. ... It has been suggested that Corolla be merged into this article or section. ... Raised thorns on the stem of the wait-a-bit climber Prickles on rose stems Thorns of the Ocotillo A spine is a rigid, pointed surface protuberance or needle-like structure on an animal, shell, or plant, presumably serving as a defense against attack by predators. ... Genera See Taxonomy of the Cactaceae A cactus (plural cacti, cactuses or cactus) is any member of the succulent plant family Cactaceae, native to the Americas. ... Nepenthes mirabilis in flower, growing on a road cut in Palau Carnivorous plants (sometimes called insectivorous plants) are plants that derive some or most of their nutrients (but not energy) from trapping and consuming animals or protozoans, especially insects and other arthropods. ... Shallot bulbs A bulb is an underground vertical shoot that has modified leaves (or thickened leaf bases) that is used as food storage organs by a dormant plant. ... Binomial name Allium cepa L. Percentages are relative to US recommendations for adults. ... In botany, a tendril is a specialized stem, leaf or petiole with a threadlike shape that is used by climbing plants for support and attachment, generally by twining around whatever it touches. ... Binomial name Pisum sativum L. A pea is the small, edible round green bean which grows in a pod on the leguminous vine Pisum sativum, or in some cases to the immature pods. ... Toothed bracts on Rhinanthus minor In botany, a bract is a modified or specialized leaf, from the axil of which a flower or flower stalk arises; or a bract may be any leaf associated with an inflorescence. ... A pseudanthium (Greek: false flower) is a special type of inflorescence, in which several flowers are grouped together to form a flower-like structure. ... Species See full list. ...

See also

The leaf blower was invented by Japanese engineers in the early 1970s and introduced to the United States as a lawn and garden maintenance tool. ... This Australian tree fern is producing a new frond by the process of circinate vernation Vernation (from vernal, since that is when leaves spring forth in Temperate regions) is the formation of new leaves or fronds. ... Cladophylls also called cladodes are photosynthetic branches or portions of a stem that resemble and function as a leaf, as in the asparagus. ... Phylloclades are flattened, photosynthetic branches or stems that resemble or perform the function of a leaf, as in certain cacti. ...

External links

Wikimedia Commons has media related to:
Leaves

Image File history File links Commons-logo. ... The Wikimedia Commons (also called Wikicommons) is a repository of free content images, sound and other multimedia files. ...


  Results from FactBites:
 
Vermont Only: Vermont Fall Foliage Report 2007/2008 (1052 words)
Vermont's foliage is always among the best because of a variety of other natural factors, including soil types, amount of forested land, topography and a broad range of tree species, with a large amount of maples.
Foliage viewing is also subjective, so, take time to check around many corners and over the brow of several hills to find your favorite.
Who: Foliage reports are a prediction of the conditions that will exist, developed from reports submitted by Vermont foresters twice weekly in September and October.
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But peony foliage is beautiful too - both the fresh new spring growth and the rich colours of autumn.
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