Question

Can someone explain the difference in homospores and heterospores? And which plants use which? And what each grow into?

Answer 1

Homospores are the plants which produce spores of same size and shape they are of one type, these are not sexually differentiated .these spores grows into bisexual gametophytes and produce both male and female gametes.

The plants using homospores are equisetum and ferns.

Heterospores:- These are the plants which produce spores of different shape and size, they are male microspores and female megaspores, they develop into male and female gametophytes . The plants using heterospores are pteridophytes and seed producing plants .

Homosporous life history:-

In this the plants has morphologically identical spores which germinates to produce bisexual (both male and female) gametophytes in pteridophytes.In bryophytes they are either bisexual or usually, unisexual (develop either into male or female) gametophytes . Each mature gametophyte has gametangia the sex organs which produce gametes. Each antheridium the male gametangium forms many motile flagellate sperms, and each archegonium the female gametangium forms one nonmotile egg. Fusion of an egg and a sperm forms a zygote, the process is called syngamy, and zygotes are diploid in nature.

Heterosporous life history:-

It is found in some pteridophytes and in the seed bearing plants. in this morphologically dissimilar spores are produced from two types of sporangia, that is- microspores, or male spores, and megaspores, or female spores.

In pteridophytes, megaspores are larger than microspores, but in seed bearing plants that is gymnosperms and angiosperms ,microspores are larger as compared to megaspores.The spores produces two types of gametophytes . The microspores develop into a microgametophyte or male gametophyte, which finally produces male gametes or sperm, and each megaspore produces a megagametophyte or female gametophyte), which produces female gametes or eggs. Fusion of an egg and a sperm forms a zygote and the diploid characteristic is restored.