Bot. [f. L. ext- (in extimus most outward, f. ex-) + -INE1.] The outer membrane of the pollen grain. Also EXINE.
1835. Lindley, Introd. Bot. (1848), I. 358. The shell of the pollen-grain … has been ascertained to consist … of two or even three membranes, of which the outer (extine) is thicker than the inner (intine).
1882. Vines, Sachs’ Bot., 505. The contents [of pollen grains] enclosed by an extine and intine, divide into two cells.
