(Anat.) One of the patches of villi found in some forms of placenta.
2.
(Bot.) A leaf borne by the caulicle or radicle of an embryo; a seed leaf. Note: Many plants, as the bean and the maple, have two cotyledons, the grasses only one, and pines have several. In one African plant (Welwitschia) the cotyledons are permanent and grow to immense proportions.
... very odd plant, agreeing with no described genus. The leaf is almost round, green on the upper side and whitish underneath, with several fibres running from the insertion of the pedicule towards the circumference, it is umbilicated as Cotyledon aquatica and Faba Aegyptia. The flowers are white, standing on single foot-stalks, of the shape of a Stramonium, but divided into 4 points only, as ... — A Voyage to New Holland • William Dampier
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