macrospore n 1: larger of the two types of spore produced in heterosporous plants; develops in ovule into a female gametophyte [syn: {megaspore}, {macrospore}]
Macrospore \Mac"ro*spore\, n. [Macro- + spore.] (Bot.) One of the specially large spores of certain flowerless plants, as {Selaginella}, etc. [1913 Webster]