O″ö‐sphere (–sfēr), n. [Gr. ῳὄν an egg + E. sphere.]
1. (Bot.) An unfertilized, rounded mass of protoplasm, produced in an oögonium.
☞ After being fertilized by the access of antherozoids it becomes covered with a cell wall and develops into an oöspore, which may grow into a new plant like the parent.
2. (Bot.) An analogous mass of protoplasm in the ovule of a flowering plant; an embryonic vesicle. Goodale.