Biology · Plant Kingdom · NEET
Heterospory means one plant makes TWO kinds of spores of different sizes. The large one is the megaspore (macrospore) and the small one is the microspore. This is different from homosporous plants (most pteridophytes) where all spores look the same. NCERT names Selaginella and Salvinia as the two heterosporous examples you must remember for NEET.
The MEGAspore (big) germinates into the FEMALE gametophyte. The MICROspore (small) germinates into the MALE gametophyte. An easy trick: Mega = Mother (female), Micro = male. NEET loves to swap these two in the options, so lock this direction in your memory.
Seed habit means the female gametophyte with the megaspore is NOT shed off; it is retained on the parent sporophyte, and the zygote grows into a young embryo while still inside that female gametophyte on the parent. So the embryo develops in a protected place on the mother plant — just like a seed. NCERT calls this event 'a precursor to the seed habit,' meaning it is an early evolutionary step towards making true seeds (seen later in gymnosperms and angiosperms).
Follow the chain: (1) The plant makes a big megaspore. (2) The megaspore is retained on the parent, not scattered. (3) The female gametophyte forms inside it, still attached to the parent. (4) After fertilisation, the zygote becomes an embryo INSIDE this female gametophyte, still on the parent sporophyte. This 'embryo protected on the parent' arrangement is the beginning of the seed idea. True naked seeds appear later in gymnosperms.
For NEET Plant Kingdom, yes — NCERT specifically names Selaginella and Salvinia as heterosporous pteridophytes. Most other pteridophytes (like Lycopodium, Psilotum, Equisetum, Pteris, Dryopteris, Adiantum) are homosporous. Also note gymnosperms and angiosperms are heterosporous too, but the classic pteridophyte pair to memorise is Selaginella and Salvinia.
No. This is a common trap. Selaginella shows the seed HABIT (a precursor step) — the embryo develops on the parent — but it does NOT form a true seed. A true seed needs an ovule and integuments and comes only in seed plants (gymnosperms and angiosperms). So say 'precursor to the seed habit,' not 'seed.'
Genera like Selaginella and Salvinia produce two kinds of spores. Such plants are known as:
Identify the pair of heterosporous pteridophytes among the following:
Select the mismatch:
Try the real previous-year questions from this chapter — each with the answer and a full solution.
Homosporous plants make only ONE kind of spore (all spores alike) — most pteridophytes such as Lycopodium and Equisetum. Heterosporous plants make TWO kinds of spores, big megaspores and small microspores — like Selaginella and Salvinia. Only heterospory shows the seed habit.
Because it starts the seed habit. When the megaspore is retained on the parent and the embryo grows inside the female gametophyte there, the young plant is protected and fed by the parent. This 'embryo on parent' idea later becomes the true seed in gymnosperms and angiosperms.
NCERT names two: Selaginella and Salvinia. Remember this exact pair — NEET has repeatedly tested it (2021, 2023).
No. They show the seed HABIT (a precursor step) but do not make a true seed. True seeds first appear in gymnosperms, where seeds are naked (not covered by a fruit).
A megaspore germinates into the female gametophyte; a microspore germinates into the male gametophyte. Trick: Mega = Mother (female), Micro = male.
