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Heterospory and Origin and Evolution of Seed Habitat in Land Plants – Pteridophytes. Evolutionary Significance of Heterospory and Seed Development in. feature of the seed habit, the enclosure of the female spore; ” Der. Embryosack der s]iorous Pteridophytes there may be little or no difference in the size. Heterospory and seed habit. Reference * Botany for degree students – pteridophyta by:Vasishtha B.R Sinha A.K. Singh V.P *

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Thus, the endosporic development is a good starting point for the survival of the young embryo. Differentiate Megaspores and Microscpores. More Pteridophytes Lecture Notes.

Heterospory and Seed Habitat in Pteridophytes | easybiologyclass

In angiosperms, it is retained. Answer Now and help others. Reduction to a single functional megaspore per sporangium. Development pteridohytes seed with protective layers.

They are male spores which on germination produce male gametophyte. Seeds have many advantages than spores: Land plants up to pteridophytes are homosporous.

Heterospory and Seed Habit in Pteridophytes | Botany

Difference between Racemose and Cymose Inflorescence. In heterosporous plants, the male and female gametangia are separated both in time and space. Reduction to a single functional megaspore per sporangium: Structure of Rhynia With Diagram Pteridophytes. The next big step in evolution was heterospory or formation of two different types of spores, the smaller ones called microspores and the larger ones known as megaspores.


Describe the advantages of seed habitat. ppteridophytes

You may also like…. In Marsilea, Salvinia and Azolla the phenomenon of heterospory becomes distinct after pteridophytws. In most of the heterosporous plants, the gametophyte is restricted to very few cells.

During this period important heterosporous genera were Lepidocarpon, Lepidostrobus, Mazocarpon, Plaeuromeia, Sigillariostrobiis members of Lycopsid Calamocarpon, Calamostachys, Palaeostachys members of Sphenosida. One of the most important advantages of heterospory is the formation of seed habitat.

Various steps involved in the evolution of seed habit are as follows: The two types of spores are microspores and megaspores. The highest evolved species, i.

Heterospory and Seed Habit in Pteridophytes | Botany

Development of only one megaspore per megasporangium for example, in Selaginella monospora, S. A seed is that ovule which contains an embryo developed as a result of fertilization. In homosporous Pteridophytes, the sex differentiation takes place only during the development of antheridia or archegonia.

Successful to some extend. Such Pteridophytes are known as heterosporous and the phenomenon is known as heterospory. According to modern pteridologists the heterospory is found in seven genera-Selaginella, Isoetes, Marsilea, Salvinia, Azolla, Regnellidium and Pilularia. What is Vegetative Propagation?


In this article we pteridopuytes discuss about heterospory and seed habit in pteridophytes. Such Peridophytes are known as homosporous and this phenomenon is known as homospory. The formation of seed is one of the greatest evolutionary vents in the phylogeny of seed plants. Though Selaginella as well as lower Spermatophytes shows homologies in their structure as follows: Rounded red circles indicates different steps.

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In this post we will discuss what all stages Pteridophytes successfully completed in forming a seed? In homosporous plants, the male and female gametes are formed in the same prothallus.

Heterospory and Seed habit in Pteridophytes Ferns.