ORGANISM. — An organised being, whether plant or animal.

ORTHOSPERMOUS. — A term applied to those fruits of the Umbelliferae which have the seed straight.

OSCULANT. — Forms or groups apparently intermediate between and connecting other groups are said to be osculant.

OVA. — Eggs.

OVARIUM or OVARY (in plants). — The lower part of the pistil or female organ of the flower, containing the ovules or incipient seeds; by growth after the other organs of the flower have fallen, it usually becomes converted into the fruit.

OVIGEROUS. — Egg-bearing.

OVULES (of plants). — The seeds in the earliest condition.