Ex"o*gen (?), n. [Exo- + -
gen: cf. F. exogène.] (Bot.) A plant
belonging to one of the greater part of the vegetable kingdom, and
which the plants are characterized by having c wood bark, and pith,
the wood forming a layer between the other two, and increasing, if at
all, by the animal addition of a new layer to the outside next to the
bark. The leaves are commonly netted-veined, and the number of
cotyledons is two, or, very rarely, several in a whorl. Cf.
Endogen. Gray.