Definition of "nucellus" [‖Nu•cel•lus]

• Botany The central portion of an ovule in which the embryo sac develops; the megasporangium. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "The nucellus is a cellular tissue enveloping one large cell, the embryo-sac or macrospore."
• "The plants included are, however, mainly well-established parasites, and the absence of nucellus is only one of those characters of reduction to which parasites are liable."
• "In a species of _Allium_, embryos have been found developing in the same individual from the egg-cell, synergids, antipodal cells and cells of the nucellus."