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Question : In which one of the following, male and female gametophytes don't have free living independent existence?

Answer»

Pteris
Funaria
Polytrichum
Cedrus

Solution :(a) In Pteris (also Dryopteris) the spore germinates to produce the prothallus. The prothallus is a small, green flat, SURFACE loving, thallus-like object. It is monoecious and bears sex organs on the ventral side. The aantheridia (male sex organs) arise amongthe rhizoida towards the posterior side of the prothallus and are emergent.The ARCHEGONIA develop in central cushion behind the apical notch.In these plants male and female, gametophytes do have free livingindependent existence.All species of Polytrichum are dioecious.The antheridia and archegonia are borne ondifferent gametophore.The plant body is an erect leafy shootbut is not the entire gametophyte.The leafy shoot arise from protonema (the JUVENILE stage).The leafy gametophore of Funaria REPRODUCES sexually by formation of antheridia and archegonia. The antheridia are formed at the summit of a relatively small, THIN, leafy shoot, whichdevelops first. The female branch arises later as a lateral outgrowth from the base of parent male shoot.Cedrus is a gymnosperm in which mainplant body is a sporophyte on which reduced type of gametophytes are formed.


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