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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Dryopteris or heterosporous e. Bot Gaz 3: Apomictically produced offspring are genetically identical to the parent plant. Some authors included all forms of asexual reproduction within apomixis, but that generalization of the term has since died out. Selaginella, Marsilea, Azolla etc. The sporophyte may be homosporous e g. 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.
In some plant familiesgenera with apomixis are quite common, for example in AsteraceaePoaceaeand Rosaceae. Meaning, General Characters and Affinities. In vitro production apogamy and apospory in bryophytes and their significance.
13 Important Characters of Pteridophytes – Explained!
Purchase Subscription prices and ordering Short-term Access To purchase short term access, please sign pteridopyytes to your Oxford Academic account above. An introduction to the embryology of the angiosperms.
Retrieved from ” https: Apogamy is a related term that has had various meanings over time. In plants with independent gametophytes notably fernsthe term is still used interchangeably with “apomixis”, and both refer to the formation of sporophytes by parthenogenesis of gametophyte cells. To purchase short term access, apospkry sign in to your Oxford Academic account above.
This definition notably does not mention meiosis. Developmental evidence helps resolve the evolutionary pteriddophytes of anther appendages in Globba Zingiberaceae. Embryologie und Fortpflanzungsbiologie der Angiospermen: Apomixis occurs in at least 33 families of flowering plants, and has evolved multiple times from sexual relatives.
Efficient induction of apospory and apogamy in vitro in silver fern Pityrogramma calomelanos L. Anybody can ask a question Anybody can answer The best answers are voted up and rise to the top.
In flowering plants, the term “apomixis” is commonly used in a restricted sense to mean agamospermyi. The possible significance of all the results is discussed.
Plant Cell Reports 25 The gametophytes develop sex organs like antheridia male pteridophytees organs and archegonia female sex organs.
The genetic control of apomixis can involve a single genetic change that affects apopory the major developmental components, formation of the megagametophyte, parthenogenesis of the egg cell, and endosperm development.
Azolla, Selaginella but a few are perennial woody tree fern e.
Apogamy, apospory and parthenogenesis in the Pteridophytes II
Apogamy is the development of an unusual haploid sporophyte from the gametophyte without the fusion of gametes. Gametophytic apomixis in flowering plants develops in several different ways. Vascular tissues present throughout the sporophyte except in reproductive parts and in gametophyte.
Ultrastructural aspects of apospory and apogamy. Phloem consists of sieve cells only. The culture of bryophytes including apogamy apospory parthenogenesis and protoplasts. Facultative apomixis means that apomixis does not always occur, i.
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This page was last edited on 8 Decemberat This article is about plants. All Pteridophytes are annual and herbaceous, e. Answer Now and help others. Although agamospermy could theoretically occur in gymnospermsit appears to be absent in that group. Agamospermy occurs mainly in two forms: Most users should sign in with their email address.
Systematics at different levels.
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 another archesporium cell.