Heterosporous pteridophytes show certain characteristics, which are precursor to the seed habit in gymnosperms. One of such characteristics is

Options

A. presence of vascular tissues
B. external water required for fertilisation
C. presence of embryo stage
D. development of embryo inside the female gametophyte.

Answer

D

Explanation

Genera like selaginella and salvinia which produce towo kinds of spores, are known as heteroporous. The megasprores and microspores germinate and give rise to female and male gametophytes, respectively the female gametophytes in these plants are retained on the parent sporohytes for variable periods. the development of the zygotes into young embroys take place within the female gametophytes. this event is the precursor to the seed habit which is considered as an importantstep in evolution.