Monocotyledons
or ENDOGENS. One of the two great classes into which all flowering plants are divided. They may be characterised as follows : Stem with the wood forming longitudinal bundles, irregularly disposed, not in concentric layers, and having no defined central pith. Leaves with usually parallel veins; exceptions to this character are not uncommon amongst Aroideoe, Dioscoreoe, and Liliaceoe. Flowers with the organs mostly in threes or fours, never in fives; in grasses, the parts are arranged in twos and threes. Embryo with a single cotyledon; first-formed leaves alternate; radicle not branching, but throwing out adventitious roots.