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Bryophytes are homosporous and monoecious but why few are dioecious?

Bryophytes are homosporous and monoecious but why few are dioecious?
To get this answer first we need to know what is the homosporous condition? The spores of bryophytes are highly specialised cells produced in the capsule of the sporophyte. These spores are morphologically alike in size and thus are homosporous. Each of the spores then germinates under suitable condition to give rise to the main gametophyte.
Monoecious and dioecious conditions refer to the gametophytic phase. With the initiation of this phase two kinds of sex organs appears ie., antherdia and archegonia. If these sex organs are developed on the same thallus, such species are monoecious (Riccia sp). On the contrary if antherdia and archegonia are borne on different thalli then they are dioecious eg., Marchantiasp.

What are Thallophyta?

What are Thallophyta?
The term “Thallophyta” is derived from the Greek word i.e., thallus means young shoot; phyta refers to plant. The plant under this division are primitive exhibiting thalloid plant body i.e., not differentiated into stem, leaves and roots. The term thallophyta was first introduced by Stephan Endlicher in 1836.
Thallophyta is the compilation of a wide variety of plants ranging from unicellular to multicellular with simple mode of reproduction. This group mainly includes members of Algae and Fungi.
Algae are autotrophic in nature comprising a range of pigments including chlorophyll. These plants mainly grow in water or in moist condition eg., Nostoc sp, Chara sp, Vaucheria sp, Diatoms, Polsiphonia sp.
Whereas members in fungal group are heterotrophic due to the absence of chlorophyll pigment. So for their survival they either live as a saprophyte, parasite or in symbiotic relation with the host species. Examples includes species of Alternaria, Saccharomyces, Ascobolus,…