American Heritage® Dictionary of the English Language, Fourth Edition
- n. See megasporangium.
Century Dictionary and Cyclopedia
- n. A sporangium containing macrospores. It is homologous with the ovule of flowering plants. Also called goniotheca.
- 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.
GNU Webster's 1913
- n. (Bot.) 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.
- n. a plant structure that produces megaspores
“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.”
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