Tag: classification of pteridophytes

The retention of the megaspore and the development of the embryo within the female gametophyte, which remains attached to the parent sporophyte, is a crucial evolutionary step toward the seed habit.

In Dryopteris, on the lowerside of the leaflet an outgrowth is present. It consists of a stalk like placenta and a flap, that protects group of sporangia. This is called as true indusium.

In Dryopteris, the annulus and the stomium help in the dehiscence of the sporangium and dispersal of spores. At maturity, the sporangium dehisces by drying action, which exerts pressure on mouth assisted by shrinkage of the annulus. Lastly mouth of sporangium open and spores are liberated.

Gametophytes have sessile jacketed multicellular sex organs. The male is antheridium and female is archegonium. Antheridia form biflagellated (Selaginella, Lycopodium) or multiflagellated (Dryopteris) male gametes. Antheridium producing about 32 anthropoids. Each anthropoid is large antinuclear coiled and multi flagellate.

A resurrection plant is any plant that can survive extreme dehydration and desiccation for years. Selaginella lepidophylla is a  a plant species that is native to America. It is an example of resurrection plant.

In mosses (bryophytes), the sporophyte is dependent on the gametophyte. In pteridophytes (like Selaginella/Ferns), the sporophyte is independent.

Selaginella is the primary example of a heterosporous pteridophyte belonging to the class Lycopsida.