[Gk.] A plant that grows by adding new wood to the interior of the stem, as a palm, rush or orchid. Opposed to exogen (q.v.). The leaves have usually parallel veins, and their flowers are in three or multiples of three parts. Endogens have no bark, because, the flow of sap being internal, bark is not required to defend the sap, as in exogens. The Endogens include palms, lilies, orchids, etc.