macrospore
IPA: mækroʊspɔr
noun
- One of the specially large spores of certain flowerless plants, as Selaginella, etc.
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Examples of "macrospore" in Sentences
- (Fig. 79, _A_, _E_), the embryo sac or macrospore.
- The macrospore divides into two cells, a large lower one, and a smaller upper one.
- The nucellus is a cellular tissue enveloping one large cell, the embryo-sac or macrospore.
- But the formation of the macrospore or embryo-sac is simpler than the corresponding process in cryptogams.
- _G_, section of a full-grown macrosporangium (ovule), × 25: i, ii, the two integuments. _sp. _ macrospore (embryo sac).
- The single macrospore (_sp. _) is very large and does not lie free in the cavity of the sporangium, but is in close contact with its wall.
- The germination of the macrospore consists in the repeated division of its nucleus to form two groups of four, one group at each end of the embryo-sac.
- In the full-grown ovule the macrospore, which in the seed plants is generally known as the "embryo sac," is completely filled with the prothallium or "endosperm."
- _Casuarina_ and others, instead of a single macrospore a more or less extensive sporogenous tissue is formed, but only one cell proceeds to the formation of a functional female cell.
- When we compare the embryo sac (macrospore) of the angiosperms with that of the gymnosperms a great difference is noticed, there being much more difference than between the latter and the higher pteridophytes.