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Ophioglossophyta

Ophioglossophyta

- Family Ophioglossaceae
- Ophioglossum
- Cheiroglossa
- Family Botrychiaceae
- Botrychium
- Botrypus
- Sceptridium
- Family Helminthostachiaceae
- Helminthostachys zeylanica The Ophioglossophyta are a small group of plants. Traditionally they are included in the division Pteridophyta, the ferns, originally as a family and later as the order Ophioglossales. However, it is now recognized that this group is wholly distinct from the ferns and apparently from the other extant groups of plants. Thus they may be given a separate division, called the Ophioglossophyta. One scheme groups them with the horsetails and whisk ferns in the division Archeophyta. The two principal families of ophioglossoids are the adders'-tongues, Ophioglossaceae, and the moonworts and grape-ferns, Botrychiaceae. Many workers still place the moonworts in the Ophioglossaceae, along with the distinct species Helminthostachys zeylanica. Other times, this species is given its own family Helminthostachiaceae. All the ophioglossoids have short-lived spores formed in sporangia lacking an annulus, and borne on a stalk that splits from the leaf blade; and fleshy roots. Many species only send up one frond or leaf-blade per year. A few species send up the fertile spikes only, without any conventional leaf-blade. The gametophytes are subterranean. The spores will not germinate if exposed to sunlight, and the gametophyte can live some two decades without forming a sporophyte. The genus Ophioglossum has the highest chromosome counts of any known plant.

External links

- [http://www.csdl.tamu.edu/FLORA/imaxxoph.htm Ophioglossophyta images] Category:Ophioglossophyta Category: Cryptogams

Ophioglossaceae

- Ophioglossaceae sensu stricto Cheiroglossa
Ophioglossum

- Botrychiaceae Botrychium
Botrypus
Sceptridium
- Helminthostachyaceae Helminthostachys Ophioglossaceae is a family of primitive ferns, currently thought to be most closely related to Psilotum, the two together forming the sibling group to the rest of the ferns. The number of genera included in the family varies between different authors' treatments, and most conservatively the family is treated as containing three genera, Ophioglossum, Botrychium, and Helminthostachys (corresponding to the three families accepted in some other treatments). These ferns differ from the other ferns in several respects:
- they produce only a single leaf at a time
- can be used as an ointment for skin rashes
- instead of the leptosporangia typical of most ferns they produce eusporangia, which are larger, contain more spores, and have thicker walls
- their sporophylls are divided into two distinct parts, the sporophore which produces sporangia and has a greatly reduced and modified blade, and the trophophore, which is very similar to the trophophylls in size, color, shape, and so forth
- their gametophytes are subterranean and rely on fungi for their energy (in other words, they are mycoheterotrophic), unlike the terrestrial, photosynthetic gametophytes found in most ferns. Members of Ophioglossaceae are usually terrestrial (excepting a few epiphytic species of Ophioglossum) and occur in both temperate and tropical areas. The leaves are usually fleshy, and in temperate areas will often turn brownish or reddish during colder months. In addition to having mycoheterotrophic gametophytes, there are a few members of Botrychium that are unique among ferns in having the sporophytes also mycoheterotrophic, producing only small, ephemeral sporophylls that do not photosynthesize. The genera Botrychium, Botrypus, Sceptridium and Helminthostachys are sometimes placed in their own families Botrychiaceae (Botrychium, Botrypus, Sceptridium) and Helminthostachyaceae (Helminthostachys) respectively. Category:Ophioglossophyta

Cheiroglossa

The hand fern (Cheiroglossa palmata), also known as the dwarf staghorn, is a terrestrial, fern-like plant. The genus Cheiroglossa is in the family Ophioglossaceae of the order Ophioglossales, a small group of non-flowering vascular plants. The family includes another genus, Ophioglossum (the adders'-tongues). The hand fern is an epiphyte, growing in old leaf bases of the Cabbage palmetto (Sabal palm). The leaves are palmately-lobed and roughly shaped like a hand. They grow up tp 30 cm wide and the margins are entire (no serration). The fertile fronds are a set of small tapering sporophores that bear the spores. There are several to many at the base of each leaf blade. On the sporophores are the sporangial clusters with sporangia in two rows, all embedded in compact, linear spikes. The main areoles large, usually more than 30 mm. The pale yellowish-brown roots are dichotomous. The gametophytes are brown to white, cylindric, and repeatedly branched. This plant is found worldwide, but in the United States, it is restricted to the far southeast, primarily Florida. It has become rare in Florida due to overcollecting and extensive drainage of natural wetlands from development and water diversion projects. It is reported to not survive cultivation. This plant is also called the "hand tongue".

References

- [http://www.natureserve.org/explorer/servlet/NatureServe?searchName=Cheiroglossa+palmata Cheiroglossa palmata]
- [http://fig.cox.miami.edu/~scofield/sofl_plants/fern_ophioglossum_palmatum.html Photos and info on the Hand fern] Category:Ophioglossophyta

Moonwort

- Botrychium boreale
- Botrychium lanceolatum
- Botrychium lunaria
- Botrychium matricariifolium
- Botrychium simplex Moonworts are seedless vascular plants of the genus Botrychium, sensu stricto. They are small, with fleshy roots, and reproduce by spores shed into the air. Some species only occasionally emerge above ground and gain most of their nourishment from an association with mycorrhizal fungi. fungi The circumscription of Botrychium is disputed between different authors; some botanists include the genera Botrypus and Sceptridium within Botrychium, while others treat them as distinct. The latter treatment is followed here. Category:Ophioglossophyta

Grape-fern

- Botrypus virginianum Grape-ferns are seedless vascular plants of the genus Botrypus, closely allied to (and previously often included in) the genus Botrychium (moonworts). They are small, with fleshy roots, reproducing by spores shed into the air. They differ from the moonworts in having at least some sterile fronds (all fronds in Botrychium are spore-bearing), and in the fronds being bi- or tri-pinnate (Botrychium are single pinnate, or rarely bipinnate). Category:Ophioglossophyta

Helminthostachys

Helminthostachys zeylanica is a terrestrial, herbaceous, fern-like plant of southeastern Asia and Australia, commonly known as Kamraj and Tukod-langit. The genus is monotypic and, just like the other members of its family, it has clusters of sporangia on stems of fertile, spike-like fronds. The rhizome of this annual plant is short, creeping, underground, and stout. They can bear either a solitary frond or several fronds. Leaves are lanceolate with the margins entire or irregularly serrate. The frond spike arises from the base of the leaves with its own stipe. Below the spike is a sterile leafy segment (the trophophore). Both it and the sporophore arise from a common petiole.

Uses

The roots of this plant are a popular medicine in China, where they are known as "Di wu gong". The roots are harvested during the wet season in July-August. Only wild plants are harvested. In Malaysia, the leaves are dried and smoked to treat bleeding nose.

References

- [http://www.tfeps.org/helminthostachys_zelaynica.htm Helminthostachys zeylanica - photos and info] Category:Ophioglossophyta

Fern

Marattiopsida
Osmundopsida
Gleicheniopsida
Pteridopsida A fern, or pteridophyte, is any one of a group of some twenty thousand species of plants classified in the Division Pteridophyta, formerly known as Filicophyta. A fern is a vascular plant that differs from the more primitive lycophytes in having true leaves (megaphylls) and from the more advanced seed plants (gymnosperms and angiosperms) in lacking seeds. Like all vascular plants, it has a life cycle, often referred to as alternation of generations, characterized by a diploid sporophytic and a haploid gametophytic phase. Unlike the gymnosperms and angiosperms, in ferns the gametophyte is a free-living organism. The life cycle of a typical fern is as follows: # A sporophyte (diploid) phase produces haploid spores by meiosis; # A spore grows by cell division into a gametophyte, which typically consists of a photosynthetic prothallus # The gametophyte produces gametes (often both sperm and eggs on the same prothallus) by mitosis # A mobile, flagellate sperm fertilizes an egg that remains attached to the prothallus # The fertilized egg is now a diploid zygote and grows by mitosis into a sporophyte (the typical "fern" plant).

Fern structure

zygote Like the sporophytes of seed plants, those of ferns consist of:
- Stems: Most often an underground creeping rhizome, but sometimes an above-ground creeping stolon (e.g., Polypodiaceae), or an above-ground erect semi-woody trunk (e.g., Cyatheaceae) reaching up to 20 m in a few species (e.g., Cyathea brownii on Norfolk Island and Cyathea medullaris in New Zealand).
- Leaf: The green, photosynthetic part of the plant. In ferns, it is often referred to as a frond, but this is because of the historical division between people who study ferns and people who study seed plants, rather than because of differences in structure. New leaves typically expand by the unrolling of a tight spiral (the fiddlehead), called circinate vernation. Leaves are further divided into two types:
- Trophophyll: A leaf that does not produce spores, instead only producing sugars by photosynthesis. Analogous to the typical green leaves of seed plants.
- Sporophyll: A leaf that produces spores. These leaves are analogous to the scales of pine cones or to stamens and pistil in gymnosperms and angiosperms, respectively. Unlike the seed plants, however, the sporophylls of ferns are typically not very specialized, looking similar to trophophylls and producing sugars by photosynthesis as the trophophylls do.
- Roots: The underground non-photosynthetic structures that take up water and nutrients from soil. They are always fibrous and are structurally very similar to the roots of seed plants. The gametophytes of ferns, however, are very different from those of seed plants. They typically consist of:
- Prothallus: A green, photosynthetic structure that is one cell thick, usually heart- or kidney-shaped, 3-10 mm long and 2-8 mm broad. The thallus produces gametes by means of:
- Antheridia: Small spherical structures that produce flagellate sperm.
- Archegonia: A flask-shaped structure that produces a single egg at the bottom, reached by the sperm by swimming down the neck.
- Rhizoids: root-like structures that consist of single greatly-elongated cells that take up water and nutrients.

Evolution and classification

Ferns first appear in the fossil record in the early-Carboniferous epoch. By the Triassic, the first evidence of ferns related to several modern families appeared. The "great fern radiation" occurred in the late-Cretaceous, when many modern families of ferns first appeared. Ferns have traditionally been grouped in the Class Filices, but modern classifications assign them their own division in the plant kingdom, called Pteridophyta. Two related groups of plants, commonly known as ferns, are actually more distantly related to the main group of "true" ferns. These are the whisk ferns (Psilophyta) and the adders-tongues, moonworts, and grape-ferns (Ophioglossophyta). The Ophioglossophytes were formerly considered true ferns and grouped in the Family Ophioglossaceae, but were subsequently found to be more distantly related. Some classification systems include the Psilopytes and Ophioglossophytes in Division Pteridophyta, while others assign them to separate divisions. Modern phylogeny indicates that the Ophioglossophytes, Psilopytes, and true ferns together constitute a monophyletic group, descended from a common ancestor. The true ferns may be subdivided into four main groups, or classes (or orders if the true ferns are considered as a class):
- Marattiopsida
- Osmundopsida
- Gleicheniopsida
- Pteridopsida The last group includes most plants familiarly known as ferns. The Marattiopsida are a primitive group of tropical ferns with a large, fleshy rhizome, and are now thought to be a sibling taxon to the main group of ferns, the leptosporangiate ferns, which include the other three groups listed above. Modern research indicates that the Osmundopsida diverged first from the common ancestor of the leptosporangiate ferns, followed by the Gleichenopsida. Pteridopsida Pteridopsida Pteridopsida Pteridopsida A more complete classification scheme follows:
- Division: Pteridophyta
- Class: Marattiopsida
- Order: Marattiales
- Order: Christenseniales
- Class: Osmundopsida
- Order: Osmundales (the flowering ferns)
- Class: Gleicheniopsida
- Subclass: Gleicheniatae
- Order: Gleicheniales (the forked ferns)
- Order: Dipteridales
- Order: Matoniales
- Subclass: Hymenophyllatae
- Order: Hymenophyllales (the filmy ferns)
- Subclass: Hymenophyllopsitae
- Order: Hymenophyllopsidales
- Class: Pteridopsida
- Subclass: Schizaeatae
- Order: Schizeales (including the climbing ferns)
- [heterosporous ferns]
- Order: Marsileales (Hydropteridales) (the water-clovers, mosquito fern, water-spangle)
- Subclass: Cyatheatae
- Order: Cyatheales (the tree ferns)
- Order: Plagiogyriales
- Order: Loxomales
- Subclass: Pteriditae
- Order: Lindseales
- Order: Pteridales (including the brakes and maidenhair ferns)
- Order: Dennstaedtiales (the cup ferns, including bracken)
- Subclass: Polypoditae
- Order: Aspleniales (the spleenworts)
- Order: Athyriales (including the lady ferns, ostrich fern, maiden ferns, etc.)
- Order: Dryopteridales (the wood ferns and sword ferns)
- Order: Davalliales (including the rabbits-foot ferns and Boston ferns)
- Order: Polypodiales (including the rock-cap ferns or Polypodies)

Economic uses

Ferns are not of major economic importance, with one possible exception. Ferns of the genus Azolla, which are very small, floating plants that do not look like ferns, called mosquito fern, are used as a biological fertilizer in the rice paddies of southeast Asia, taking advantage of their ability to fix nitrogen from the air into compounds that can then be used by other plants. Other ferns with some economic significance include:
- Dryopteris filix-mas (male fern), used as a vermifuge
- Rumohra adiantoides (floral fern), extensively used in the florist trade
- Osmunda regalis (royal fern) and Osmunda cinnamomea (cinnamon fern), the root fiber being used horticulturally; the fiddleheads of O. cinnamomea are also used as a cooked vegetable
- Matteuccia struthiopteris (ostrich fern), the fiddleheads used as a cooked vegetable in North America
- Pteridium aquilinum (bracken), the fiddleheads used as a cooked vegetable in Japan
- Diplazium esculentum (vegetable fern), a source of food for some native societies
- Tree ferns, used as building material in some tropical locales In addition, a great many ferns are grown in horticulture.

Misunderstood names

Several non-fern plants are called "ferns" and are sometimes popularly believed to be ferns in error. These include:
- "Asparagus fern" - This may apply to one of several species of the monocot genus Asparagus, which are flowering plants. A better name would be "fern asparagus".
- "Sweetfern" - This is a shrub of the genus Comptonia.
- "Air fern" - This is an unrelated aquatic animal that is related to a coral; it is harvested, dried, dyed green, then sold as plant that can "live on air". It looks like a fern but is actually a skeleton. In addition, the book Where the Red Fern Grows has elicited many questions about the mythical "red fern" named in the book. There is no such known plant, although there has been speculation that the Oblique grape-fern, Sceptridium dissectum, could be referred to here, because it is known to appear on disturbed sites and its fronds may redden over the winter.

External links and sources

- Moran, Robbin C. (2004). A Natural History of Ferns. Portland, OR: Timber Press. ISBN 0-88192-667-1.
- [http://tolweb.org/tree?group=Filicopsida&contgroup=Embryophytes Tree of Life Web Project: Filicopsida]
- A classification of the [http://www.anbg.gov.au/projects/fern/taxa/classification.html ferns and their allies]
- [http://www.jaknouse.athens.oh.us/ferns/bookfern.html A fern book bibliography]
- [http://www1.akira.ne.jp/~unzen/pteridophyta.html Register of fossil Pteridophyta]
- [http://delta-intkey.com/britfe/ L. Watson and M.J. Dallwitz (2004 onwards). The Ferns (Filicopsida) of the British Isles.] http://delta-intkey.com Category:Pteridophyta ja:シダ植物門

Whisk fern

- Psilotum nudum (L.) Beauvois
- Psilotum complanatum Sw. Psilotum (whisk ferns) is a genus of fern-like vascular plants, the sole genus in the family Psilotaceae and the order Psilotales. They have traditionally been thought not to be true ferns, but rather, odd "primitive" vascular plants that reproduce solely by spores, without seeds. Recent evidence has however suggested that they may in fact be ferns that have lost a number of pteridophytic characteristics, but their status is still uncertain. There are two species, Psilotum nudum and Psilotum complanatum, with a hybrid between them known, Psilotum x intermedium W. H. Wagner. The distribution of Psilotum is tropical and subtropical, in the New World, Asia, and the Pacific. The highest latitudes known are in South Carolina and southern Japan for P. nudum. Category:Plants ms:Paku-pakis whisk

Ophioglossum

Ophioglossum austroasiaticum
Ophioglossum azoricum
Ophioglossum californicum
Ophioglossum crotalophoroides
Ophioglossum engelmanii
Ophioglossum lusitanicum
Ophioglossum nudicaule
Ophioglossum palmatum
Ophioglossum pedunculosum
Ophioglossum petiolatum
Ophioglossum pusillum
Ophioglossum pycnosticum
Ophioglossum reticulatum
Ophioglossum tenerum
Ophioglossum thermale
Ophioglossum vulgatum Ophioglossum (adder's-tongue) is a genus of about 25-30 species of ferns in the family Ophioglossaceae, with a cosmopolitan but primarily tropical and subtropical distribution. The name Ophioglossum comes form the Greek, and means "snake-tongue". Adders-tongues are so-called because the spore-bearing stalk is thought to resemble a snake's tongue. Each plant typically sends up a small, undivided leaf blade with netted venation, and the spore stalk forks from the leaf stalk, terminating in sporangia which are partially concealed within a structure with slitted sides. The plant grows from a central, budding, fleshy structure with fleshy, radiating roots. When the leaf blade is present, there is not always a spore stalk present, and the plants do not always send up a leaf, sometimes going for a year to a period of years living only under the soil, nourished by association with soil fungi. Ophioglossum has the highest chromosome count of any living organism, with 1260. Category:Ophioglossophyta

Ophioglossaceae

Botrychiaceae

Botrychium
Botrypus
Sceptridium The Botrychiaceae (moonwort family) is a small family of one to three genera in the order Ophioglossales. Many botanists include it within the family Ophioglossaceae.

External link

- [http://arthur_haines.tripod.com/botrychium.htm Classification of New England Botrychiaceae] Category:Ophioglossophyta Category:Plant families

Spore

:This article is about biological spores. For the video game, see Spore (game). :S'pore is also a common abbreviation for Singapore The term spore has several different meanings in biology. Categorization by function:
- Diaspores are dispersal units of fungi, as well as mosses, ferns, fern allies, and a few other plants.
- resting stage in the life cycle of some bacteria (see endospore) and loosely applied to some animal resting stages
- Chlamydospores are thick-walled resting spores in fungi.
- Zygospores are thick-walled resting spores (hypnozygotes) of zygomycetous fungi which are produced by sexual gametocystogamy and can give rise to a conidiophore ("zygosporangium") with asexual conidiospores. Categorization by origin during life cycle:
- Meiospore is a product of meiosis (the critical cytogenetic stage of sexual reproduction), meaning it is haploid and will give rise to a haploid daughter cell(s) or a haploid individual. An example is the parent of gametophytes of the higher vascular plants (angiosperms and gymnosperms)—the microspores (give rise to pollen) and megaspores (give rise to ovules) found in flowers and cones; these plants accomplish dispersal by means of seeds.
- Mitospore (conidium, conidiospore) is an asexually produced propagule, the result of mitosis. Most fungi produce mitospores. Mitosporic fungi are also known as anamophic fungi (compare teleomorph or deuteromycetes). Categorization by motility - spores can be differentiated by whether they can move or not:
- Zoospore can move by means of one or more flagellum. It can be found in some algae.
- Aplanospore cannot move, but could potentially grow flagella.
- Autospore cannot move and does not have the potential to ever develop any flagella.
- Ballistospore is actively discharged from fungal fruit body (mushroom).
- Statismospore is not actively discharged from fungal fruit body (see puffball). Spores can be formed sexually or asexually, and therefore many different kinds of spores exist. In common parlance, the difference between "spore" and "gamete" (both together called gonites) is that a spore will germinate and develop into a Thallus (tissue) of some sort, whereas a gamete needs to combine with another gamete before developing further. However, the terms are somewhat interchangeable when referring to gametes, as indicated by the technical terminology given in the second definition above. A chief difference between spores and seeds as dispersal units is that spores have very little stored food resources compared with seeds, and thus require more favorable conditions in order to successfully germinate. In their favor, spores are very hardy and require much less energy to produce. The strategy employed in producing spores, is to reach all the favorable locations by producing and dispersing very large numbers. Spore came from a Greek word meaning seed. However, seeds (of seed plants) are not the same as spores, but are the fusion of gametes.

Diaspores

In the case of spore-shedding vascular plants such as ferns, wind distribution of very light spores provides great capacity for dispersal. Also, spores are less subject to animal predation than seeds because they contain almost no food reserve, however they are more subject to fungal and bacterial predation. Their chief advantage is that, of all forms of progeny, spores require the least energy and materials to produce. Vascular plant spores are always haploid and vascular plants are either homosporous or heterosporous. Plants that are homosporous produce spores of the same size and type. Heterosporous plants, such as spikemosses, quillworts, and some aquatic ferns produce spores of two different sizes: the larger spore in effect functioning as a "female" spore and the smaller functioning as a "male". Under high magnification, spores can be categorized as either monolete spores or trilete spores. In monolete spores, there is a single line on the spore indicating the axis on which the mother spore was split into four along a vertical axis. In trilete spores, all four spores share a common origin and are in contact with each other, so when they separate each spore shows three lines radiating from a center. Category:Botany Category:Biological reproduction Category:Germ cells ja:胞子

Sporangium

A sporangium (pl., sporangia) is a plant or fungal structure producing and containing spores. Sporangia occur on angiosperms, gymnosperms, ferns, fern allies, mosses, algae, and fungi. Microsporangia are the structures on the stamens of flowers called anthers, and the pollen-producing structures on the microsporophylls of male conifer cones. Megasporangia are the comparable "female" structures on these plants, associated with the flower carpel and the megasporangial cone. On ferns, the mature plant is a sporophyte that develops sporangia, tiny, stalked sacs which contain meiospores, on all or just certain leaves (called sporophylls if sporangia are present). In mosses, the little case that rises above the vegetative growth on a thin stalk is a sporangium often called a capsule that, as in ferns, produces meiospores. This sporophytic (diploid) growth arises out of the gametophytic (haploid) archegonium after the ovum is fertilized. The sporophyte initially has some chlorophyll, but later turns brown and becomes dependent upon the gametophyte for nutrition, which is absorbed through the foot (base of the stalk), embedded in the archegonial tissues. Categorized based on developmental sequence, eusporangia and leptosporangia are differentiated in the vascular plants. In a leptosporangium, found only in ferns, development involves a single initial cell that becomes the stalk, wall, and spores within the sporangium. There are around 64 spores in a leptosporangium. In a eusporangium, characteristic of all other vascular plants and some primitive ferns, the initials are in a layer (i.e., more than one). A eusporangium is larger (hence contain more spores), and its wall is multi-layered. Although the wall may be stretched and damaged, resulting in only one cell-layer remaining. A cluster of sporangia that have become fused in development is called a synangium. This structure is most prominent in Psilotum.
- See also: archegonium, antheridium
- For bacteria-related information see endospore Category:Plant anatomy Category:Botany Category:Mycology ja:胞子嚢

Root

In vascular plants, the root is that organ of a plant body that typically lies below the surface of the soil (compare with stem). However, this is not always the case, since a root can also be aerial (that is, growing above the ground) or aerating (that is, growing up above the ground or especially above water). On the other hand, a stem normally occurring below ground is not exceptional either (see rhizome). So, it is better to define root as a part of a plant body that bears no leaves, and therefore also lacks nodes. There are also important internal structural differences between stems and roots. The two major functions of roots are 1) absorption of water and inorganic nutrients and 2) anchoring the plant body to the ground.

Root structure

nodes At the tip of every growing root is a conical covering of tissue called the root cap. It usually is not visible to the naked eye. It consists of undifferentiated soft tissue (parenchyma) with unthickened walls covering the apical meristem. The root cap provides mechanical protection to the meristem cells as the root advances through the soil, its cells worn away but quickly replaced by new cells generated by cell division within the meristem. The root cap is also involved in the production of mucigel, a sticky mucilage that coats the new formed cells. These cells contain statoliths, starch grains that move in response to gravity and thus control root orientation. The outside surface of a root is the epidermis. Recently produced epidermal cells absorb water from the surrounding environment and produce outgrowths called root hairs that greatly increase the cell's absorptive surface. Root-hairs are very delicate and generally short-lived, remaining functional for only a few days. However, as the root grows, new epidermal cells emerge and these form new root hairs, replacing those that die. The process by which water is absorbed into the epidermal cells from the soil is known as osmosis. For this reason, water that is saline is more difficult for most plant species to absorb. Beneath the epidermis is the cortex, which comprises the bulk of the root. Its main function is storage of starch. Intercellular spaces in the cortex aerate cells for respiration. An endodermis is a thin layer of small cells forming the innermost part of the cortex and surrounding the vascular tissues deeper in the root. The tightly packed cells of the endodermis contain a substance known as suberin and create an impermeable barrier of sorts. Water can only flow in one direction through the endodermis: in towards the center of the root, rather than outward from the stele to the cortex. The vascular cylinder, or stele, consists of the cells inside the endodermis. The outer part, known as the pericycle, surrounds the actual vascular tissue. In monocotyledonous plants, the xylem and phloem cells are arranged in a circle around a pith or center, whereas in dicotyledons, the xylem cells form a central "hub" with lobes, and phloem cells fill in the spaces between the lobes. dicotyledon

Root growth

Early root growth is a function of the apical meristem located near the tip of the root. The meristem cells more or less continuously divide, producing more meristem, root cap cells (these sacrificed to protect the meristem), and undifferentiated root cells. The latter will become the primary tissues of the root, first undergoing elongation, a process that pushes the root tip forward in the growing medium. Gradually these cells differentiate and mature into specialized cells of the root tissues. Roots will generally grow in any direction where the correct environment of air, nutrients and water exists to meet the plant's needs. Roots will not grow in dry soil. Over time, given the right conditions, roots can crack foundations, snap water lines, and lift sidewalks. At germination, roots grow downward due to gravitropism, the growth mechanism of plants that also causes the shoot to grow upward. In some plants (such as ivy), the "root" actually clings to walls and structures; this is known as thigmotropism, or response to touch. Most plants experience growth only along the apical meristems; this is known as primary growth, which encompasses all vertical growth. On the other hand, secondary growth encompasses all lateral growth, a major component of woody plant tissues. Secondary growth occurs at the lateral meristems, namely the vascular cambium and cork cambium. The former forms secondary xylem and secondary phloem, while the latter forms the periderm, found only in woody plants. In woody plants, the vascular cambium, originating between the xylem and the phloem, forms a cylinder of tissue along the stem and root. The cambium layer forms new cells on both the inside and outside of the cambium cylinder, with those on the inside forming secondary xylem cells, and those on the outside forming secondary phloem cells. As secondary xylem accumulates, the "girth" (lateral dimensions) of the stem and root increases. As a result, tissues beyond the secondary phloem (including the epidermis and cortex, in many cases) tend to be pushed outward and are eventually "sloughed off" (shed). At this point, the cork cambium (noting that this process only occurs in woody plants) begins to form the periderm, consisting of protective cork cells containing suberin. In roots, the cork cambium originates in the pericycle, a component of the vascular cylinder. cork The vascular cambium produces new layers of secondary xylem annually. This dead tissue is responsible for most water transport through the vascular tissue (systems and roots).

Types of roots

A true root system consists of a primary root and secondary roots (or lateral roots). The primary root originates in the radicle of the seedling. During its growth it rebranches to form the lateral roots. Generally, two categories are recognized:
- the taproot: the primary root is prominent and has a single, dominant axis; there are fibrous secondary roots running outward. Usually allows for deeper roots capable of reaching low water tables. Most common in dicots
- the primary root is not dominant: the whole root system is fibrous and branches in all directions. Most common in monocots. Adventitous roots arise from the stem and not from another root. They usually occur in monocots and pteridophytes, but also in a few dicots, such as strawberry (Fragaria vesca) and white clover (Trifolium repens). white clover]

Specialized roots

The roots, or parts of roots, of many plant species have become specialized to serve adaptive purposes besides the two primary functions described in the introduction.
- Aerating roots (or pneumatophores): roots rising above the ground, especially above water such as in some mangrove genera (Avicennia, Sonneratia)
- Aerial roots: roots entirely above the ground, such as in ivy (Hedera helix) or in epiphytic orchids. They function as prop roots or anchor roots.
- Contractile roots: they pull bulbs or corms of monocots deeper in the soil through expanding radially and contracting longitudinally. They show a wrinkled surface.
- Haustorial roots: roots of parasitic plants that can absorb water and nutrients from another plant, such as in mistletoe (Viscum album) and Rafflesia.
- Proteoid roots or cluster roots: dense clusters of rootlets of limited growth that develop under low phosphate or low iron conditions in plants from the following families Betulaceae, Casuarinaceae, Eleagnaceae, Moraceae, Fabaceae and Myricaceae.
- Stilt roots: these are adventitious support roots, common among mangroves. They grow down from lateral branches, branching in the soil.
- Storage roots: these roots are modified for storage of nutrients, such as carrots and beets
- Tubiferous roots: A portion of a root forms into a roundish knob called a (tuber) for food.

Rooting depths

The distribution of vascular plant roots within the soil depends on plant life form, and the spatial and temporal availability of water and nutrients in the soil. The deepest roots are generally found in deserts and temperate coniferous forests; the shallowest in tundra, boreal forest and temperate grasslands. The deepest observed living root, at least 60 m below the ground surface, was observed during the excavation of an open-pit mine in Arizona, USA.

References

- Brundrett, M. C. 2002. Coevolution of roots and mycorrhizas of land plants. New phytologist 154(2): 275-304. (Available online: [http://dx.doi.org/10.1046/j.1469-8137.2002.00397.x DOI] | [http://www.blackwell-synergy.com/links/doi/10.1046/j.1469-8137.2002.00397.x/abs/ Abstract] | [http://www.blackwell-synergy.com/links/doi/10.1046/j.1469-8137.2002.00397.x/full/ Full text (HTML)] | [http://www.newphytologist.org/Brundrett.pdf Full text (PDF)])
- Chen, R., E. Rosen, P. H. Masson. 1999. Gravitropism in Higher Plants. Plant Physiology 120 (2): 343-350. (Available online: [http://www.plantphysiol.org/cgi/content/full/120/2/343 Full text (HTML)] | [http://www.plantphysiol.org/cgi/reprint/120/2/343.pdf Full text (PDF)]) - article about how the roots sense gravity.
- Clark, Lynn. 2004. [http://www.eeob.iastate.edu/classes/bot404/docs/404root104.pdf Primary Root Structure and Development] - lecture notes
- Raven, J. A., D. Edwards. 2001. Roots: evolutionary origins and biogeochemical significance. Journal of Experimental Botany 52 (Suppl 1): 381-401. (Available online: [http://jxb.oupjournals.org/cgi/content/abstract/52/suppl_1/381 Abstract] | [http://jxb.oupjournals.org/cgi/content/full/52/suppl_1/381 Full text (HTML)] | [http://jxb.oupjournals.org/cgi/reprint/52/suppl_1/381.pdf Full text (PDF)])
- Schenk, H.J., and R.B. Jackson. 2002. The global biogeography of roots. Ecological Monographs 72 (3): 311-328.
- Phillips, W.S. 1963. Depth of roots in soil. Ecology 44 (2): 424.

External link

- [http://www.ualr.edu/~botany/roots.html Introduction to Botany - University of Arkansas] Category:Plant physiology Category:Plant anatomy Category: plant morphology ja:根 ms:Akar

Frond

Frond refers to the leaf structure of ferns. The term is colloquially applied to the leaves of palms, cycads, and other plants with pinnately compound leaves. A significant difference is that, unlike the leaves of the latter, fern fronds bear the reproductive structures (spore-bearing structures) of the sporophyte plant. Because many ferns grow fronds that are held more vertical than horizontal, the "upper" and "lower" surfaces of a frond are more correctly referred to as the adaxial and abaxial surfaces, respectively. A fern frond consists of a stipe, the stem supporting the blade, and the blade consists of both a laminar (flattened) phoyosynthetic tissue and a rachis—that portion of the stem to which the laminar tissue is attached. The blades of fern fronds may vary from being simple (undivided) to being highly dissected, even "lace-like". If the leaf tissue is undissected, or the dissections do not reach to the rachis, the frond may be described as lobed or pinnatifid. Otherwise, the blade is compound and each large division of the laminar tissue arising from the rachis is called a pinna (pl., pinnae). The main vein or mid-rib of a pinna is known as a costa (pl., costae). Pinnae may be arranged along the rachis either directly opposite one another or alternating up the stem. The arrangement may change from the base of a blade to the tip, as in the example of Blechnum shown below (from base to tip: pinnae opposite to alternate, and pinnatisect to pinnatifid). Many ferns have pinnae that are divided two or more times, and the level of division of the fronds is termed pinnate (or 1-pinnate), or twice-pinnate (2-pinnate), or the like. Each secondary division (division of a pinna) is termed a pinnule, and its mid-vein, a costule. A few species of ferns with divided fronds are not pinnate, but are palmate or bifurcate. bifurcate On some or all mature blades (usually on the abaxial surface) occur sporangia, which bear the spores. The sporangia are clustered in a sorus (pl., sori) or "fruit dot". Associated with each sorus in many species is a mebranous structure called an indusium: an outgrowth of the blade surface that may partly cover the sporangial cluster. Fronds also may bear hairs or scales, glands, and, in some species, bulblets for vegetative reproduction. Each frond arises from the stem or rhizome, which in most species is concealed in the ground or creeps along the ground (or branch or rock) surface. Growth of a fern frond differs from that of a leaf of a flowering plant. The fern frond unrolls from a tightly-coiled structure called a "fiddle-head" (see circinate vernation). Category: Pteridophyta Category: plant morphology

Leaf

:This article is about the leaf, a plant organ. See Leaf (disambiguation) for other meanings. ---- 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 chloroplast containing cells (chlorenchyma tissue) 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. frond frond frond

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 point at which the petiole attaches to the stem is called the leaf axil. Not every species produces leaves with all of these structural parts. 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 types, arrangements, and forms. A leaf is considered to be a plant organ, typically consisting of the following tissues: # An epidermis that covers the upper and lower surfaces # An interior chlorenchyma called the mesophyll # An arrangement of veins (the vascular tissue). stipule

Epidermis

The epidermis is the outer multi-layered group of cells covering the leaf. It forms the boundary between the plant and 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 usually transparent (epidermal cells lack chloroplasts) and coated on the outer side with a waxy cuticle that prevents water loss. The cuticle may be 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. 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. The epidermis is covered with pores called stomata (sing., stoma), 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. Trichomes or hairs grow out from the epidermis in many species.

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 (= 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 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 less 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. 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 homogenous aerenchyma (thin-walled cells separated by large gas-filled spaces). Their stomata are situated at the upper surface. Leaves are normally green in color, which comes from chlorophyll found in plastids in the chlorenchyma cells. Plants that lack chlorophyll cannot photosynthesize. 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 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.

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 veins are made up of:
- xylem, which brings water from the stem 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 (= ground tissue), called pith, with usually some structural collenchyma tissue present.

Leaf morphology

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. phloem Leaves may be classified in many different ways, and the type is usually characteristic of a species, although some species produce more than one type of leaf. The terminology associated with describing leaf morphology is presented (with illustrations) at [http://wikibooks.org/wiki/Botany:_Leaves_(forms) Wikibooks].

Basic leaf types

- Ferns have fronds.
- Conifer leaves are typically needle-, awl-, or scale-shaped
- Angiosperm (flowering plant) leaves: the standard form includes stipules, petiole, and lamina.
- Microphyll leaves.
- Sheath leaves (type found in most grasses).
- Other specialized leaves.

Arrangement on the stem

As a stem grows, leaves tend to appear arranged around the stem in away that optimizes yield of light. In essence, leaves come off the stem in a spiral pattern, 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 series: 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 gives the number of complete turns or gyres until the leaf arrives at the initial position. The denominator gives 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. The fact that an arrangement of anything in nature can be described by a mathematical formula is not in itself mysterious. Mathematics is 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. However, we can more easily describe the arrangement of leaves using the following terms:
- Alternate — leaf attachments singular at nodes, and leaves alternate direction, to a greater or lesser degree, along the stem.
- Opposite — leaf attachments paired at each node; decussate if, as typical, each successive pair is rotated 90° going along the stem; or distichous if not rotated, but two-ranked (in the same plane).
- 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). Note: opposite leaves may appear whorled near the tip of the stem.
- Rosulate — leaves form a rosette ( = a cluster of leaves growing in crowded circles from a common center). Fibonacci series

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 one 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.
- Palmately compound leaves have the leaflets radiating from the end of the petiole, like fingers off the palm of a hand. There is no rachis, e.g. Cannabis (hemp) and Aesculus (buckeyes).
- Pinnately compound leaves have the leaflets arranged along the main or mid-vein (called a rachis in this case).
- 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. some Sorbus (whitebeams). ;Characteristics of the petiole:
- Petiolated leaves have a petiole.
- In peltate leaves, the petiole attaches to the blade inside from the blade margin.
- Sessile or clasping leaves do not have a petiole. In sessile leaves the blade attaches directly to the stem. In clasping leaves, the blade partially or wholly surrounds the stem, giving the impression that the shoot grows through the leaf such as in Claytonia perfoliata of the purslane family (Portulacaceae). 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. ;Characteristics of the stipule
- 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. They 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
- 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

Venation (arrangement of the veins)

rhubarb There are two subtypes of venation, craspedodromus (the major veins stretch up to the margin of the leaf) and camptodromous (major veins come close to the margin, but bend before they get to it).
- 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.
pteridophyte

Leaf terminology

;Shape See Leaf shape

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).

Tip of the leaf

- 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.

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 surface of a leaf can be described by several botanical terms:
- 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.

Hairiness (trichomes)

Leaves can show several degrees of hairiness. The meaning of several of the following terms can overlap. See also : Trichome.
- 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

In order to survive in a harsh environment, leaves can adapt in the following ways:
- Hairs develop on the leaf surface to trap humidity in dry climates, creating a large boundary layer to lessen water loss
- Leaves rustle to move humidity away from the surface reducing the boundary layer resistance between the leaf and the air.
- Plant prickles are modified clusters of epidermal hairs
- Waxy leaf surfaces form to prevent water loss
- Small, shiny leaves to deflect the sun's rays
- Thicker leaves to store water (e.g. rhubarb)
- Change to spines instead of laminar (blade) leaves (e.g. cactus)
- Shrink (to phyllodes) or disappear (with the appearance of cladodes), as photosynthetic functions are transferred to the leaf stem (Acacia species)
- Change shape to deflect wind or reduce wind resistance
- Leaves to trap insects (e.g. pitcher plant)
- Change to bulb parts to store food (e.g. onion)
- Produce aromatic oils to deter herbivores (e.g. eucalypts)
- Protect as spines, which are modified leaves.

External links

- [http://www.ibiblio.org/botnet/glossary/b_i.html Position and Arrangement] Category:Photosynthesis Category:Plant physiology Category:plant morphology Category:Plant anatomy ko:잎 ja:葉 th:ใบไม้

Sporophyte

A sporophyte is the diploid structure or phase of life of a sexually reproducing plant. Each living cell of the sporophyte contains two complete sets of chromosomes. The sporophyte is the dominant life form in ferns, gymnosperms, and angiosperms (flowering plants). In plants that undergo alternation of generations, the sporophyte produces haploid spores that develop into a gametophyte. Through mitosis, the gametophyte produces a zygote that becomes the sporophyte. In some plants, the sporophyte is initially parasitic on the gametophyte for a time. Category:Plant morphology Category:Botany

Ophioglossum

Category:Cryptogams

Cryptogams is a name referring to plants that do not reproduce by seeds. The term is sometimes used as a term of convenience but since the organisms in question are not regarded as a coherent group by contemporary plant systematics, the word is considered obsolete in taxonomy. sort10 Cryptogams

Adnan Catic

Felix Sturm (
- 31. Januar 1979 in Leverkusen; eigentlich Adnan Catic) ist ein deutscher (bosnischer Abstammung) Profiboxer. Sturm gab am 27. Januar 2001 sein Profidebut gegen Antonio Ribeiro. Sechs Monate zuvor hatte Sturm die Olympischen Spiele in Sydney erreicht, verlor dort aber gegen den Amerikaner Jermain Taylor. Nach 16 erfolgreich bestrittenen Kämpfen gewann Sturm den WBO Intercontinental Titel im Mittelgewicht. Am 13. September 2003 ermöglichte eine verletzungsbedingte Absage des Deutschen Bert Schenk einen Titelkampf Sturms gegen den Argentinier Héctor Javier Velazco um den WBO-Titel, den Sturm überraschenderweise mit 2 zu 1 Stimmen nach Punkten für sich entscheiden konnte. Nach einer Titelverteidigung gegen Rubén Varón Fernández musste Sturm am 5. Juni 2004 gegen den Amerikaner Oscar de la Hoya in Las Vegas verteidigen. Trotz einer starken Leistung verlor Sturm seinen WBO-Titel gegen den mehrmaligen Weltmeister de la Hoya umstritten nach Punkten. Sturm, Felix Sturm, Felix Sturm, Felix

zak�ady bukmacherskie Doda i Virgin wegetarianizm darmowe statystyki depresja

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