Exogens

Exogens, a name formerly applied to the class Dicotyledons (q.v.) among angiospermous plants, with which were included the gymnosperms, since they agree in the growth of their stems in thickness being exogenous - that is, in a general sense external, taking place, as it does, through the activity of the cambium (q.v.), which, though under the bark, is external to the wood of the stem.