Reproduction in Gymnosperms

Reproduction in Gymnosperms:-

> Strobilus or cone is the reproductive structure of gymnosperms. Both male and female strobili can be present on the same (seen in Pinus) or on different trees (seen in Cycas). Gymnosperm plants are heterosporous. They produce different spores, which are the haploid microspores and megaspores.

> Male Cones:- The male strobili or male cones have microsporophylls, which have the microsporangia that produce the haploid microspores. Some of these microspores develop into male gametes called the pollen grains, while the rest degenerate.

> Female Cones:- The megasporophylls form a cluster and are called as the female strobili or cones. They bear the ovules having the megasporangium. Thus produces the haploid megaspores and a megaspore mother cell.

> The megaspore mother cell undergoes meiotic division produces four megaspores. One of these megaspores develops into the multicellular female gametophyte. The female gametophyte also has two or more archegonia, which are the female sex organs.

> Fertilization:- When the pollen grains are released from the microsporangium, they get dispersed through wind and reach the female cones. The pollen grain develops a pollen tube, which grows towards the archegonium.

> The discharge of male gametes happens near the mouth of the archegonium. The fusion of the male and female gametes occurs. After fertilization, a zygote develops to form the embryo and the ovule forms the seed. The following figure shows the life cycle of a gymnosperm.