Question

Heterospory i.e., formation of two types of spores – microspores and megaspores is a characteristic feature in the life cycle of a few members of pteridophytes and all spermatophytes. Do you think heterospory has some evolutionary significance in plant kingdom?

Answer 1

Heterospory definition:

Heterospory is defined as the production of two types of spores which differ in size (morphologically), origin and other aspects like function, by the same sporophytic land plant. For example, pteridophytes like Selaginella, Salvinia.

Features of plants showing heterospory:

Species that show heterospory show the following characteristics:-

● Microspores produce male gametophytes.

● Megaspores produce female gametophytes.

● The female gametophytes develop inside a megasporangium that is retained within the sporophyte.

● The zygotes and embryos develop within the female gametophyte.

Evolutionary significance:

Heterospory ensures better developmental conditions and greater chances of survival of zygotes and embryos. They are not affected by harsh ecological conditions. Heterospory is considered as the precursor of seed habit (seed formation and development).