Microspore

n.

1.

(Bot.) One of the exceedingly minute spores found in certain flowerless plants, as Selaginella and Isoetes, which bear two kinds of spores, one very much smaller than the other. Cf. Macrospore.

Noun

1.

microspore - smaller of the two types of spore produced in heterosporous plants; develops in the pollen sac into a male gametophyte

spore