ovule A structure in angiosperms and gymnosperms that, after fertilization, develops into a seed. In gymnosperms the ovules are unprotected, whereas in angiosperms they are protected by the megasporophyll (which forms the carpel). One or several ovules may be contained in the carpel and each is attached to the carpel wall by a stalk (funicle). When mature, the angiosperm ovule consists of a central mass of tissue, the nucellus, surrounded by 1 or 2 protective layers, the integuments, which eventually give rise to the seed coat. Within the nucellus is a large oval structure, the embryo sac, which has developed from the megaspore and contains the naked egg cell.

ov·ule / ˈōvyoōl; ˈäv-/ • n. a small or immature ovum. ∎ Bot. the part of the ovary of seed plants that contains the female germ cell and after fertilization becomes the seed.DERIVATIVES: ov·u·lar / -lər/ adj.

ovule The part of the female reproductive organs of seed plants that consists of the nucellus, embryo sac, and integuments. The ovules of gymnosperms are situated on ovuliferous scales of the female cones while those of angiosperms are enclosed in the carpel. After fertilization, the ovule becomes the seed.

ovule In seed-bearing plants, part of the reproductive organ that contains an egg cell or ovum and develops into a seed after fertilization. In angiosperms (having flowers), ovules develop inside an ovary. In gymnosperms (without flowers), ovules are borne on the inner surface of the cone without any covering.

ovule (bot.) rudimentary seed; (zool.) unfertilized ovum. XIX. — F. ovule — modL. ōvulum, dim. of L. ōvum EGG1; see -ULE.