APOSPORY IN PTERIDOPHYTES PDF

The investigations in Pteridophytes probably of most interest and importance ing of apogamy and apospory, it is important to define these terms at the outset. Some of the most important characters of Pteridophytes are as follows: Apogamy and Apospory: Sometimes deviation in the regular alternation if generations. Apogamy, apospory and parthenogenesis in the Pteridophytes II Steil, W.N.. Bot Rev: This is a supplement to the review which appeared in Bot.

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Apospory is the development of unusual diploid gametophyte from the vegetative parts of sporophyte and not from the spores.

In plants with both apomictic and meiotic embryology, the proportion of the different types can differ at different times of year, [11] and photoperiod can also change the proportion. Close mobile search navigation Article navigation. The apomicts actually have discovered the effectiveness of mass production long pteridophyytes Mr Henry Ford applied it to the production of the automobile.

Apogamy is the development of an pteridoophytes haploid sporophyte from the gametophyte without the fusion of gametes. Parthenogenesis apogamy and apospory in alaria crassifolia laminariales.

Apogamy, apospory and parthenogenesis in the Pteridophytes II

The spore germinates into an inconspicuous, free-living, photosynthetic thalIoid gametophyte called prothallus. Plant reproduction Asexual reproduction. Pteridophyres was induced on the sexual cotyledonary and juvenile sporeling leaveS.

Thus “normal asexual reproduction ” of plants, such as propagation from cuttings or leaves, has never been considered to be apomixis, but replacement of the seed by a plantlet or replacement of the flower by bulbils pteridophyttes categorized as types of apomixis. In vitro production of apogamy and apospory in bryophytes and their significance. Primary root short lived and replaced by adventitious roots.

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The differentiation apospofy rhizome segments into gametophytes or sporophytes was conditioned by the length of the rhizome segments and the sucrose concentration of the medium. Biological Journal of the Linnean Society. Systematics at different levels. International Botanical Congress Abstracts Agamospermy, asexual reproduction through seeds, occurs in flowering plants through many different mechanisms [5] and a simple hierarchical classification of the different types is not possible.

Embryologie und Fortpflanzungsbiologie der Angiospermen: The life cycle is diplohaplontic which shows heteromorphic type of alternation of generations.

Apospory | botany |

Selaginella, Marsilea, Azolla etc. Bot Rev 5 8: Bot Gaz 3: Leaves with petiole, excised from aseptically raised plants from excised cultured buds, also exhibited apospory, while no success was achieved with the excised leaves of the parent plantS.

Apospory and apogamy in a species of Tectaria. If you originally registered with a username please use that to sign in. The evolutionary biology of plants.

Some authors included all forms of asexual reproduction within apomixis, but that generalization of the term has since died out.

13 Important Characters of Pteridophytes – Explained!

But Psilopsids are rootless plants having rhizoids. The sporophyte may be homosporous e g.

Most users should sign in with their email address. In vitro studies on apogamy, apospory and controlled differentiation of rhizome segments of the fern, Ampelopteris prolifera Retz.

Consequently, there are almost as many different usages of terminology for apomixis in angiosperms as there are authors on the subject. They are therefore often called microspecies. Botanical Journal of the Linnean Society 62 4: For similar processes in animals and Oomycetes, see Parthenogenesis. Anybody can ask a question Anybody can answer The best answers are voted up and rise to the top.

See also androgenesis and androclinesis described below, a type of male apomixis that occurs in a conifer, Cupressus dupreziana. Views Read Edit View history. In heterosporous forms, 2 types of spores develop i. This definition notably does not mention meiosis. The culture of bryophytes including apogamy, apospory, partenogenesis and protoplasts. The sporophytes of plants of these groups may also have the ability to form a plant that looks like a gametophyte but with the ploidy level of the sporophyte, a phenomenon known as apospory.

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Apogamy is a related term that has had various meanings over time. Although the evolutionary advantages of sexual reproduction are lost, apomixis pteridopuytes pass along traits fortuitous for evolutionary fitness. Considerable confusion has resulted because diplospory is often defined to involve the megaspore mother cell only, but a number of plant families have a multicellular archesporium and the megagametophyte could originate from aposporry archesporium cell.

The genetic control of apomixis can involve a single genetic change that affects all the major developmental components, formation of the megagametophyte, parthenogenesis of the egg cell, and endosperm development.

Ultrastructural aspects of apospory and apogamy. Rhizome segments of various length were cultured on media containing different concentrations of sucrose. The cause of apospory involves deficiency of mineral nutrition, development of leaves under dim light etc. This page was last edited on 8 Decemberat Because apomictic plants are genetically identical from one generation to the next, each lineage has some pteridophyte the characters of a true speciesmaintaining distinctions from other apomictic lineages within the same genuswhile having much smaller differences than is normal between species of most genera.

Agamospermy occurs mainly in two forms: This article is about plants.