Smaller of the two types of spore produced in heterosporous plants

• Develops in the pollen sac into a male gametophyte

Wikipedia Word definitions in Wikipedia
Microspores are land plant spores that develop into male gametophytes , whereas megaspores develop into female gametophytes. The male gametophyte gives rise to sperm cells, which are used for fertilization of an egg cell to form a zygote . Microspores are ...

The Collaborative International Dictionary Word definitions in The Collaborative International Dictionary
Microspore \Mi"cro*spore\ (m[imac]"kr[-o]*sp[=o]r), n. [Micro- + spore.] (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. ...

Wiktionary Word definitions in Wiktionary
n. (context botany English) Smaller of the two spore produced by plants, compare megaspore.

WordNet Word definitions in WordNet
n. smaller of the two types of spore produced in heterosporous plants; develops in the pollen sac into a male gametophyte

Douglas Harper's Etymology Dictionary Word definitions in Douglas Harper's Etymology Dictionary
1856, from micro- + spore .