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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

Ophioglossaceae

Moonwort

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

Helminthostachys zeylanica

Uses

References

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

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

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

Gametophyte

A gametophyte is the haploid structure or phase of life of a sexually-reproducing plant. Each cell of a gametophyte contains one complete set of chromosomes. The gametophyte can be the dominant part of the plant's life cycle as in mosses, or very reduced as in ferns and flowering plants (angiosperms), where the female form (ovule) is known as a megagametophyte and the male form (pollen) is called a microgametophyte, the dominant phase of life for bryophytes (nonvascular plants). An early developmental stage in the gametophyte of both mosses and ferns (immediately following the meiospore) is called the Protonema. See also : Sporophyte, Alternation of generations, Archegonium, Antheridium Category:Botany

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

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

Category:Ophioglossophyta

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Lijst van leden van het IOC

Het Internationaal Olympisch Comité (IOC) heeft momenteel 105 leden. Een aantal krijgt een zetel in het IOC vanwege een bestuursfunctie als voorzitter van een internationale sportbond (zoals Hein Verbrugge voor de wielerbond UIC). Anderen worden op persoonlijke titel gekozen door het IOC zelf. Internationaal Olympisch Comité Internationaal Olympisch Comité

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Ophioglossophyta

External links

Ophioglossaceae

Cheiroglossa

References

Moonwort

Grape-fern

Helminthostachys

Uses

References

Fern

Fern structure

Evolution and classification

Economic uses

Misunderstood names

External links and sources

Whisk fern

Ophioglossaceae

Moonwort

Botrychiaceae

External link

Helminthostachys zeylanica

Uses

References

Spore

Diaspores

Sporangium

Frond

Gametophyte

Sporophyte

Ophioglossum

Category:Ophioglossophyta

Lijst van leden van het IOC

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