Simulation · Biology · Class 11
From free spores to a seed
From the lesson Homospory, heterospory and the seed habit in Plant Kingdom. Change the values and watch what happens.
From free spores to a seedBiology · Class 11
The idea behind it
NCERT §3.3
- Most pteridophytes make spores of only one kind; they are homosporous.
- Selaginella and Salvinia make two kinds: large megaspores (macrospores) and small microspores. They are heterosporous.
- Megaspores grow into female gametophytes and microspores into male gametophytes.
- In heterosporous plants the female gametophyte stays on the parent sporophyte for a variable time, and the zygote grows into a young embryo inside that female gametophyte.
- This is a forerunner of the seed habit, which is regarded as an important step in evolution.