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.
|Published (Last):||25 October 2009|
|PDF File Size:||13.96 Mb|
|ePub File Size:||8.98 Mb|
|Price:||Free* [*Free Regsitration Required]|
The gametophytes of bryophytesand less commonly ferns and lycopods can develop a group of cells that grow to look like a sporophyte of the species but with the im level of the gametophyte, a phenomenon known as apogamy.
The possible significance of all the results is discussed.
13 Important Characters of Pteridophytes – Explained!
Abstract Apogamy was induced in the fern Ampelopteris prolifera by culturing the gametophytes on mineral nutrients supplemented with various concentrations of sucrose.
Close mobile search navigation Article navigation. The culture of bryophytes including apogamy apospory parthenogenesis and protoplasts.
Maheshwari  used the following im classification of types of apomixis in flowering plants:. But Psilopsids are rootless plants having rhizoids. The University of Chicago press.
Apomixis – Wikipedia
Purchase Subscription prices and ordering Short-term Access To purchase short term access, please sign in to your Oxford Academic account above.
Apogamy, apospory and parthenogenesis in the Pteridophytes II. See also androgenesis and androclinesis described below, a type of male apomixis that occurs in a conifer, Cupressus dupreziana. In some genera, it is possible to identify and name hundreds or even thousands of microspecies, which may be grouped together as species aggregatestypically listed in floras with the convention ” Genus species agg. Sign in via your Institution Sign in.
Aposporj alerts New issue alert. pterldophytes
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. Developmental evidence helps resolve the evolutionary origins of anther appendages in Globba Zingiberaceae.
The life cycle is diplohaplontic which shows heteromorphic type of alternation of generations. Phloem consists of sieve cells only. Lycopodium, Selaginella, and Isoetes or megaphyllous. Marine Biology Berlin 18 4: Illuminating the systematics of the Spiranthes sinensis species complex Orchidaceae: Examples of apomixis can be found in the genera Crataegus hawthornsAmelanchier shadbushSorbus rowans and whitebeamsRubus brambles or blackberriesPoa meadow grassesNardus stricta MatgrassHieracium hawkweeds and Taraxacum dandelions.
For similar processes in animals and Oomycetes, see Parthenogenesis. The differentiation of rhizome segments into gametophytes or sporophytes was conditioned by the length of the rhizome segments and the sucrose concentration of the medium.
Apogamy, apospory, and parthenogenesis in the Pteridophytes. 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.
Anybody can ask a question Anybody can answer The best answers are voted up and rise to the top. They are therefore often called microspecies. Biological Journal of the Linnean Society. Surrogate mother for endangered Cupressus “. This definition notably does not mention meiosis. The genetic control pteridophytees 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.
Systematics at different levels. In Embryology of angiosperms.
Meaning, General Characters and Affinities. Cytology of apogamy and apospory in Osmunda javanica Bl.