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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It appears likely [5] that all apomixis in plants is facultative; in other words, that “obligate apomixis” is an artifact of insufficient observation missing uncommon sexual reproduction. In some cases sporophylls for compact structures called cones or strobili e.

The gametophytes develop sex organs like antheridia male sex organs and archegonia female sex organs. Maheshwari [8] used the following simple classification of types of apomixis in flowering plants:. Developmental evidence helps resolve the evolutionary origins of anther appendages in Globba Zingiberaceae.

In vitro studies on apogamy, apospory and controlled differentiation of rhizome segments of the fern, Ampelopteris prolifera Retz. Biological Journal of the Linnean Society. 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.

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German speakers might prefer to consult Rutishauser Agamospermy occurs mainly in two forms: Apogamy is a related term that has had various meanings over time. Pteridophyted, there pgeridophytes almost as many different usages of terminology for apomixis in angiosperms as there are authors on the subject.

This is a question and answer forum for students, teachers and general visitors for exchanging articles, answers and notes. Sign In Forgot password? For androgenetic alopecia, see Pattern hair loss. Email alerts New issue alert. apospoy

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 ni categorized as types of apomixis. Apomictically produced offspring are genetically identical to the parent plant.

Natural apogamy is common in ferns like Dryopteris, Adiantum, Osmunda, Pteris etc.

13 Important Characters of Pteridophytes – Explained!

It furthers the University’s objective of excellence in research, scholarship, and education by publishing worldwide. Facultative apomixis means that apomixis does not always occur, i. 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.

The leaves bearing sporangia are called sporophylls. Oxford University Press is a department of the University of Oxford. Some authors included all forms of asexual reproduction within apomixis, but that generalization of the term has since died out. Views Read Edit View history. Lycopodium, Selaginella, and Isoetes or megaphyllous. Dryopteris or heterosporous e.

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13 Important Characters of Pteridophytes – Explained!

Textbook of botany Strasburger’s textbook of botany, rewritten. Apospory was induced on the sexual cotyledonary and juvenile pteirdophytes leaveS. The spore germinates into an inconspicuous, free-living, photosynthetic thalIoid gametophyte called prothallus.

Cytology of apogamy and apospory in Osmunda javanica Bl. In some plant familiesgenera with apomixis are quite common, for example in AsteraceaePoaceaeand Rosaceae. Leaves may be microphyllous e. In heterosporous forms, 2 types of spores develop i. For similar processes in animals and Oomycetes, pteridophytrs Parthenogenesis.

Pollination of an endangered Caladenia species Orchidaceae by nectar-foraging behaviour of a widespread species of colletid bee. Sign in via your Institution Sign in.

Sometimes deviation in the regular alternation if generations are noticed in the form of apogamy and apospory. In vitro production of apogamy and apospory in bryophytes and their significance.

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