EXOGENOUS

(Or. ti, and ye/KOAtaw, / grow.) A term applied to those plants a transverse slice of whose stem exhibits a central cellular substance or pith, an external cellular and fibrous ring or bark, and an intermediate woody ma , and certain fine lines radiating from the pith to the bark through the wood, and called medullary rays. They are called Exogens, because they add to their wood by succe ive external additions; and are the same as what are otherwise called Dicotyledons. They constitute one of the primary cla es into which the vegetable world is divided, characterized by their leaves being reticulated; their stems having a distinct deposition of bark, wood, and pith; their embryo with two cotyledons; and by their flowers usually formed on a quinary type. [s. 443]