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McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.



in heterosporous Pteridophyta and in seed plants, the organ in which one or several megaspores develop. Megasporangia are found singly in the axils of sporophylls (in Selaginella), on the sporophyll in a special cavity (in Isoetes), or inside sporocarps (in the order Hydropteridales). In seed plants the nucellus—the central part of the ovule—is homologous to the megasporangium.

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.