En"do*gen (?), n. [Endo- + - gen: cf. F. endogène.] (Bot.) A plant which increases in size by internal growth and elongation at the summit, having the wood in the form of bundles or threads, irregularly distributed throughout the whole diameter, not forming annual layers, and with no distinct pith. The leaves of the endogens have, usually, parallel veins, their flowers are mostly in three, or some multiple of three, parts, and their embryos have but a single cotyledon, with the first leaves alternate. The endogens constitute one of the great primary classes of plants, and included all palms, true lilies, grasses, rushes, orchids, the banana, pineapple, etc. See Exogen.