Image Antheridia.jpg right thumb 240px Diagram of antheridium anatomy An antheridium or antherida plural antheridia is a haploid structure or organ producing and containing male gamete s called antherozoids or sperm . It is present in the gametophyte phase of lower plant s like moss es and fern s, and also in the primitive vascular Psilotophyta psilotophytes . Many alga e and some Fungus fungi , for example ascomycete s and water mould s, also have antheridia during their reproductive stages. An antheridium typically consists of sterile cell biology cell s and spermatogenous tissue biology tissue . The sterile cells may form a central support structure or surround the spermatogenous tissue as a protective jacket. The spermatogenous cells give rise to spermatid s via mitotic cell division . In bryophyte s, the antheridium is borne on an antheridiophore , a stalk like structure that carries the antheridium at its apex. In many gymnosperm s and all angiosperm s, the male gametophytes have been reduced to Pollen pollen grains and their antheridia have been reduced to a single generative cell within the pollen grain. During pollination , this generative cell divides and gives rise to two sperm nuclei. The female counterpart to the antheridium is the archegonium . References C.Michael Hogan. 2010. http www.eoearth.org article Fern Fern . Encyclopedia of Earth. National council for Science and the Environment . Washington, DC Gallery gallery Image Hypnum cupressiforme perichaetialblaetter.jpeg center Magnified view of developing antheridia in Hypnum cupressiforme center gallery Category Plant anatomy Category Plant reproduction Botany stub bg ca Anteridi cs Pelatka de Antheridium es Anteridio fr Anth ridie gl Anter deo io Anteridio he kk lv Anter dijs nl Antheridium pl Plemnia pt Anter deo ru tr Anterozoit uk zh ... more details
Unreferenced stub auto yes date December 2009 A gametangium plural gametangia is an Organ anatomy organ or cell biology cell in which gamete s are produced that is found in many multicellular protist s, algae , Fungus fungi , and the gametophyte s of plant s. In contrast to gametogenesis in animal s, a gametangium is a haploid structure and formation of gametes does not involve meiosis . Types of gametangia Depending on the type of gamete produced in a gametangium, several types can be distinguished. Female Main Archegonium Oogonium Female gametangia are most commonly called Archegonium archegonia . They produce egg cell s and are the sites for fertilization . Archegonia are common in algae and primitive plants as well as gymnosperm s. In flowering plant s, they are replaced by the embryo sac inside the ovule . Male Main Antheridium The male gametangia are most commonly called Antheridium antheridia . They produce Sperm sperm cells that they release for fertilization. Antheridia producing non motile sperm spermatia are called spermatangia . Some antheridia do not release their sperm. For example, the oomycete antheridium is a syncytium with many sperm Cell nucleus nuclei and fertilization occurs via fertilization tubes growing from the antheridium and making contact with the egg cells. Antheridia are common in the gametophytes in lower plants such as bryophyte s, fern s, cycad s and ginkgo . In higher plants such as conifer s and flowering plants, they are replaced by pollen grain s. Isogamous In isogamy , the gametes look alike and cannot be classified into male or female. For example, in zygomycete s, two gametangia single cells at the end of hypha e form upon contact with each other and fuse into a zygospore . Category Reproduction Category Reproductive system Category Germ cells Botany stub cs Gametangium da Gametangium de Gametangium fr Gam tange kk lv Gametangiji nl Gametangium pl Gametangium pt Gamet ngio ru uk ... more details
Unreferenced date May 2007 Image Hyaloperonospora parasitica hyphae oospore 2.jpg thumb right 300px Oospores of Hyaloperonospora parasitica , agent of the downy mildew in the middle An oospore is a thick walled sexual spore that develops from a fertilized oosphere union of oogonium and antheridium in some algae and fungi . Also the result of plasmogamy karyogamy in oomycetes, which in turn leads to the development of hyphae, then mycelium. Category Reproduction biology stub cs Oosf ra de Oospore es Oospora fr Oospore io Oosporo nl O spore pl Oospora pt O sporo ... more details
Sac fungi form ascogonium and antheridium with trichogyne bridge As it approaches a mate, a haploid sac fungus develops one of two complementary organs, a female ascogonium or a male antheridium. These organs ... forms, that provides a passage for nuclei to travel from the antheridium to the ascogonium ... more details
italictitle Taxobox name Cavicularia densa regnum Plant ae divisio Marchantiophyta classis Marchantiopsida ordo Blasiales familia Blasiaceae genus Cavicularia genus authority Steph. ref name Stephani 1897 species C. densa binomial Cavicularia densa binomial authority Steph. ref name Stephani 1897 cite journal last Stephani first F. year 1897 title Hepaticae japonicae journal Bulletin de l Herbier Boissier series S r. 2 volume 5 pages 76 108 ref Cavicularia densa is the only species in the Marchantiophyta liverwort genus Cavicularia . It is distinguished from Blasia by the absence of a collar around the base of the sporophyte capsule, and a clustered arrangement of sperm producing antheridium antheridia . Cavicularia is endemic to Japan , where it grows on fine soil. The chemical compound cavicularin was isolated from this species. The compound is notable for being the first such compound isolated from nature with optical activity . References Reflist Category Flora of Japan Category Liverworts Bryophyte stub ja nn Cavicularia densa ... more details
sexuality Dioicous pteridophytes produce only antheridium antheridia male organs or archegonium archegonia female organ on a single gametophyte body. Monoicous pteridophytes produce both antheridium ... more details
italictitle Taxobox name Blasia pusilla image Blasia pusilla 300908a.jpg image width 240px image caption Blasia pusilla growing on a tree in Germany. regnum Plant ae divisio Marchantiophyta classis Marchantiopsida ordo Blasiales familia Blasiaceae genus Blasia genus authority Carolus Linnaeus L. , 1753 ref name Linnaeus species B. pusilla binomial Blasia pusilla binomial authority Micheli ref name Micheli Carolus Linnaeus L. ref name Linnaeus synonyms Jungermannia biloba small Swartz, 1803 small br Jungermannia blasia small Hook., 1816 small Blasia pusilla is the only species in the Marchantiophyta liverwort genus Blasia . It is distinguished from Cavicularia by the presence of a collar around the base of the sporophyte capsule, and a scattered arrangement of sperm producing antheridium antheridia . References Reflist refs ref name Linnaeus cite book last Linnaeus first C. year 1753 title Species Plantarum edition 1st volume Tomus II page 1138 ref ref name Micheli cite book last Micheli first P. A. year 1729 title Nova Plantarum Genera juxta Tournefortii methodum disposita location Florence page 14, plate vii ref External links Wikispecies Blasia pusilla commons Blasia pusilla Category Liverworts Bryophyte stub ja nn Blasia pusilla fi R yhel sammal ... more details
Infobox Anatomy Name Oogonium Latin GraySubject 3 GrayPage 38 Image Caption Image2 Caption2 System MeshName Oogonia MeshNumber A05.360.490.690.700 Oogonium plural oogonia may refer to either a primordial oocyte in a female fetus or the female gametangium of certain thallophyte s. in the fetus Main Oogenesis Oogonia are formed in large numbers by mitosis early in fetus fetal development from germ cell primordial germ cell s. In humans they start to develop between weeks 4 and 8 and are present in the fetus between weeks 5 and 30. Once the primordial germ cells have arrived in the ovary , they develop into oogonia. Oogonia migrate from the yolk sac to the genital ridge site of the future ovaries located on the posterior abdominal wall. Oogonia develop by mitosis . However, some of them become primary oocytes , which begin meiosis which is halted in prophase I. When they have entered Prophase I of meiosis they become primary oocyte s it is important to note that this process is complete before birth, in contrast to spermatogenesis . Primary oocytes are present from week 10 until menopause at 53 years in human females. in thallophytes In phycology and mycology , oogonium refers to a female gametangium if the union of the male motile or non motile and the female gamete takes place within this structure. ref name Stegenga, Bolton and Anderson 97 Stegenga, H. Bolton, J.J. and Anderson, R.J. 1997. Seaweeds of the South African West Coast. Bolus Herbarium, University of Cape Tow. ISBN 0 7992 1793 X ref ref name Smyth 55 Smyth, G.M. 1955. Cryptogamic Botany. vol. 1. McGraw Hill Book Company ref Oogonia are usually rounded cell biology cell s or sacs containing one or more oosphere s. The male antheridium usually produces many cells with flagella except in the Rhodophyta which have no flagella. ref name Fitsch 65 Fritsch, F.E. 1965. The Structure and Reproduction of the Algae. Vol. 1 Cambridge University Press ref References reflist External links http www.erin.utoronto.ca w3b ... more details
Image Liverwort prothallus.jpg thumb right Liverwort Prothallus A prothallium , or prothallus from Latin pro forwards and Greek language Greek thallos twig is usually the gametophyte stage in the life of a fern or other pteridophyte , i.e. a spore bearing plant with vascular tissue . Occasionally the term is also used to describe the young gametophyte of a Marchantiophyta liverwort or Sphagnum peat moss as well. The prothallium develops from a Germination germinating spore . It is a short lived and inconspicuous heart shaped structure typically 2 5 millimeters wide, with a number of rhizoid s root like hairs growing underneath, and the sex organs archegonium female and antheridium male . Appearance varies quite a lot between species. Some are green and conduct photosynthesis while others are colorless and nourish themselves underground as saprotrophs . Image Dixonia prothallus.jpg thumb right 250px Prothallus of the tree fern Dicksonia antarctica note new moss plants for scale Alternation of generations Pteridophyte Spore bearing plants , like all plants, go through a life cycle of alternation of generations . The fully grown sporophyte , what the layman refers to as the fern , produces genetically unique spore s in the sori by meiosis . The haploid spores fall from the sporophyte and germinate by mitosis , given the right conditions, into the gametophyte stage, the prothallus. The prothallus then develops independently for several weeks it grows sex organs and produces ovum ova and sperm flagellated sperm . After rainfall, the sperm are able to swim to the ova for fertilization to form a diploid sporophyte cell. This cell divides by mitosis and grows out of the gametophyte into a new fern, which will produce new spores that will grow into new prothallia etc., thus completing the life cycle of the organism . Advantages of alternation of generations There are two important evolutionary advantages to the alternation of generations plant life cycle. Firstly, by ... more details
Taxobox image Sphaerocarpos texanus.jpg image width 240px image caption Female plants of Sphaerocarpos texanus bearing mature sporophytes. regnum Plant ae divisio Marchantiophyta classis Marchantiopsida ordo Sphaerocarpales familia Sphaerocarpaceae genus Sphaerocarpos species S. texanus binomial Sphaerocarpos texanus binomial authority Aust. ref cite journal last Austin first C. F. year 1877 title New Hepaticae journal Bulletin of the Torrey Botanical Club volume 8 pages 157 158 ref synonyms Sphaerocarpus berterii small Aust., 1873 small br Sphaerocarpus californicus small Aust., 1879 small br Sphaerocarpus europaeus small Lorbeer, 1934 small br Sphaerocarpus terrestris small Bisch., 1827 small Sphaerocarpos texanus is a species of Marchantiophyta liverwort in the Sphaerocarpaceae family, found in the Americas, northern Africa and Europe. Description S. texanus are small, thallus thalloid , dioecy dioecious liverworts. ref name H Cite journal authorlink C. C. Hayes title Sphaerocarpos hians sp. nov., with a revision of the genus and illustrations of the species journal Bull. Torr. Bot. Club volume 37,5 pages 215 230 year 1910 ref The species is sexual dimorphism sexually dimorphic , with male plants usually 3 5 mm in diameter, females up to 12 mm in diameter ref name M Cite journal authorlink D. N. McLetchie title Sex specific germination response in the liverwort Sphaerocarpos texanus Sphaerocarpaceae journal Bryologist volume 104,1 pages 69 71 year 2001 ref . Both male bearing antheridium antheridia and female bearing archegonium archegonia plants are bright green, with the thallus branching up to several times ref name H . The plant is a winter annual, appearing in autumn and dying in spring ref name M . Notably, the spore spores occur in sets of four, called tetrads. Unlike most other species of liverwort, the spores stay in these tetrads until they germinate ref name H ref name M . Habitat The plant is found on flat, lightly shaded soil. Usually by roadsides re ... more details
, designated as A1 and A2. When mated, Antheridium antheridia introduce gametes into Oogonium oogonia , either by the oogonium passing through the antheridium amphigyny or by the antheridium attaching ... more details
Italic title Taxobox name Chara image CharaFragilis.jpg image caption Chara globularis regnum Plant ae divisio Charophyta classis Charophyceae ordo Charales familia Characeae genus Chara genus authority Carolus Linnaeus L. , 1753 subdivision ranks Species subdivision See text Chara is a genus of green algae in the family Characeae . Structure Chara species are multicellular and superficially resemble land plants because of Plant stem stem like and leaf like structures. The branching system is complex with branches derived from apical cells which cut off segments at the base to form nodal and internodal cells alternately. They are typically anchored to the littoral Substrate biology substrate by means of branching underground rhizoid s. Chara plants are rough to the touch because of deposited calcium salts on the cell wall. The metabolic processes associated with this deposition often give Chara plants a distinctive and unpleasant smell of hydrogen sulfide . ref F.E.Round, The Biology of the algae, Ernest Arnold, 1966 ref Morphology The plant body is a gametophyte. It consists of a main axis differentiated into nodes and internodes , dimorphic branches long brach of unlimited growth and short branches of limited growth , rhizoids multicellular with oblique septa and stipulodes needle shaped structures at the base of secondary laterals.chara is also known as stoneworts. Occurrence Species are found in fresh water, particularly in limestone areas throughout the northern temperate zone. They prefer less oxygenated and hard water and are not found in the waters where mosquito larvae are present. Chara grow submerged attached to the muddy bottom of the pools and ponds of clear water. They are covered with calcium carbonate deposits. Reproduction Chara reproduces vegetatively and sexually. Vegetative reproduction takes place by tubers, amylum stars and secondary protonema. The fructifications for sexual reproduction are globule or antheridium male and nucule or archegonium ... more details
italic title Taxobox name Sphaerotheca castagnei image image caption regnum Fungus Fungi divisio Ascomycota classis Leotiomycetes ordo Erysiphales familia Erysiphaceae genus Sphaerotheca fungus Sphaerotheca species S. castagnei binomial Sphaerotheca castagnei binomial authority Joseph Henri L veill L v. Sphaerotheca castagnei is a species of ascomycete fungi in the Erysiphaceae family. A plant pathogen , it causes a form of Powdery mildew . Description The mycelium is abundant and persistent or sometimes inconspicuous, occurring on either side or both sides of the infected leaves. The perithecia are abundant, scattered or somewhat aggregated, small, usually about 75 micrometre m long, but varying from 60&ndash 100 m. The texture is soft, surface uneven, reticulations very large and irregular, 20&ndash 30 m. The appendages are long, stout, usually colored throughout, but sometimes colorless, flexuous, somewhat uneven in width, and more or less interwoven with the mycelium. The ascus is rather small, elliptical or suborbicular in shape. ref cite book title North American Pyrenomycetes last Ellis JB, Everhart JM. year 1892 publisher Newfield location New Jersey pages 8&ndash 9 ref Development of the perithecium The oogonium and antheridium , which are formed where two neighboring hypha e approach, each contain a single nucleus cell nucleus . The cell wall between these organs is dissolved at the time of fertilization and the male and female nuclei unite and a fresh wall is laid down between the two organs. File Perithecium no text.PNG thumb left Perithecium with 8 pairs of ascospores green in each ascus Now the wall of the future perithecium beings to form by the development of a number of upright hyphal branches around the oogonium, forming a pseudo parenchymatous tissue, while the other branches later absorbed grow into the interior of the developing perithecium, while the outer cell walls become flattened and darker in color. Like other species in ... more details
Taxobox status image Moos 5772.jpg image width 250px regnum Plant ae divisio Marchantiophyta classis Marchantiopsida ordo Marchantiales familia Marchantiaceae genus Marchantia species M. polymorpha binomial Marchantia polymorpha binomial authority Carolus Linnaeus L. synonyms Marchantia alpestris br Marchantia aquatica Marchantia polymorpha , sometimes known as the common liverwort or umbrella liverwort , is a large Marchantiophyta liverwort with a wide distribution around the world. It is variable in appearance and has several subspecies . It is dioecious , having separate male and female plants. Description It is a thallus thallose liverwort which forms a rosette of flattened thalli with forked branches. The thalli grow up to 10 cm long with a width of up to 2 cm. It is usually green in colour but older plants can become brown or purplish. The upper surface has a pattern of hexagonal markings. The underside is covered by many root like rhizoid s which attach the plant to the soil. The plants produce umbrella like reproductive structures known as gametophore s. The gametophores of female plants consist of a stalk with star like rays at the top. These contain archegonium archegonia , the organs which produce the ovum ova . Male gametophores are topped by a flattened disc containing the antheridium antheridia which produce sperm . Reproduction Marchantia polymorpha can reproduce both sexual reproduction sexually and asexual reproduction asexually . Sexual reproduction involves sperm from the male plant fertilisation fertilizing ova from the female plants. A fertilized ovum develops into a small sporophyte plant which remains attached to the larger gametophyte plant. The sporophyte produces male and female spore s which develop into free living gametophyte plants. Asexual reproduction can occur when older parts of the plant die and newer branches develop into separate plants. It can also occur by means of gemma botany gemma e, balls of cells which are geneti ... more details
found in mosses. Fertile plants bearing Antheridium antheridia and sporophyte s were first ... producing antheridium antheridia are not surrounded by perichaetium perichaetial leaves or other protective ... more details
, hyphae develop male and female Gametangium gametangia called, respectively, Antheridium antheridia and Oogonium oogonia . ref name Hughes Because Aphanomyces euteiches is homothallic the antheridium ... mating type s are not needed for sexual reproduction. ref name Hughes The antheridium fertilizes ... more details
a male and a female type gametangia called an antheridium male and an oogonium female . The antheridium is amphigynous in the species, meaning that the antheridium may remain in this male form of the gametangia ... more details
Taxobox image Lycopodium annotinum1.jpg image width 240px image caption Lycopodium annotinum regnum Plant ae divisio Lycopodiophyta classis Lycopodiopsida ordo Lycopodiopsida Lycopodiales familia Lycopodiaceae genus Lycopodium subdivision ranks Species subdivision see text Lycopodium from Greek lukos , wolf and podion , diminutive of pous , foot is a genus of clubmoss es, also known as ground pines or creeping cedar , ref http www.encyclopedia.com topic club moss.aspx 1E1 clubmoss The Columbia Encyclopedia, Sixth Edition, 2008 ref in the family Lycopodiaceae , a family of fern allies see Pteridophyta . They are flower less, vascular, terrestrial or epiphyte epiphytic plant s, with widely branched, erect, prostrate or creeping stems, with small, simple, needle like or scale like leaf leaves that cover the stem and branches thickly. The leaves contain a single, unbranched vascular strand and are microphyll s by definition. The kidney shaped or reniform spore cases sporangium sporangia contain spores of one kind only spore isosporous, homosporous and are borne on the upper surface of the leaf blade of specialized leaves sporophylls arranged in a cone like strobilus at the end of upright stems. The club shaped appearance of these fertile stems gives the clubmosses their common name. Lycopods reproduce sexually by spores. The plant has an underground sexual phase that produces gamete s, and this alternates in the life cycle with the spore producing plant. The prothallium developed from the spore is a subterranean mass of tissue of considerable size and bears both the male and female organs antheridium and archegonia . However, it is more common that they are distributed vegetatively through above or below ground rhizomes . There are approximately 950 species, Fact date January 2009 with 37 species widely distributed in temperate and tropical climates, though they are confined to mountain s in the tropics. The genera Diphasiastrum , Lycopodiella and Huperzia were once inc ... more details
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