from The American Heritage® Dictionary of the English Language, 4th Edition
- n. See megasporangium.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. A sporangium or conceptacle containing only large spores; opposed to microsporangium. Both are found in the genera Selaginella, Isoetes, and Marsilea, all of which are ferns or remotely allied to ferns.
from the GNU version of the Collaborative International Dictionary of English
- n. A sporangium or conceptacle containing only large spores; -- opposed to
microsporangium. Both are found in the genera Selaginella, Isoctes, and Marsilia, plants remotely allied to ferns.
from The Century Dictionary and Cyclopedia
- n. A sporangium containing macrospores. It is homologous with the ovule of flowering plants. Also called goniotheca.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- n. a plant structure that produces megaspores
Sorry, no etymologies found.
Consult one of the best of them, Webster's New World Dictionary, and what you find is a miniature encyclopedia filled with the explanations of initials, proper names, and entries like "macrosporangium" and "abhenry," which are not and never will be words of the English language.
We have already examined in some detail the structure of the macrosporangium or ovule.
_G_, section of a full-grown macrosporangium (ovule), × 25: i, ii, the two integuments. _sp. _ macrospore (embryo sac).
_C_, longitudinal section of a spike, with a single macrosporangium at the base; the others, microsporangia, × 3.
Secondly, the nucleus of the ovule corresponds with the macrosporangium of Selaginella, through the connecting link of the conifers, where the ovule is of similar origin and position to the macrosporangium of the
The development of the ovule, which represents the macrosporangium, is very similar to the process in Gymnosperms; when mature it consists of one or two coats surrounding the central nucellus, except at the apex where an opening, the micropyle, is left.
Wordnik is becoming a not-for-profit! Read our announcement here.