Elementary botany . -In trillium theand in dentaria thecompound pistil,plants, for examplecolumbine, to aleaf, the margins ofwhich are foldedaround so that theymeet and enclosethe ovules or spo-rangia. 654. If we cutacross the com-pound pistil of tril-lium we find thatthe infoldings of thethree pistils meet toform three partialpartitions whichextend nearly to the center, dividing off three spaces. In thesespaces are the ovules which are attached to the infolded we make cross sections of a pistil of the May-apple (podo-. Fig. 387 Section of pistil of tril-lium , showi
Elementary botany . -In trillium theand in dentaria thecompound pistil,plants, for examplecolumbine, to aleaf, the margins ofwhich are foldedaround so that theymeet and enclosethe ovules or spo-rangia. 654. If we cutacross the com-pound pistil of tril-lium we find thatthe infoldings of thethree pistils meet toform three partialpartitions whichextend nearly to the center, dividing off three spaces. In thesespaces are the ovules which are attached to the infolded we make cross sections of a pistil of the May-apple (podo-. Fig. 387 Section of pistil of tril-lium , showing position ofovules (macrosporangia). Fig. (Podo-phyllum peltatum). GAMETOPHYTE AND SPOROPHYTE. 327 phyllum) and through the ovules when they are quite young, weshall find that the ovule has a structure like that shown in fig. m is a cell much larger than the surrounding ones. This iscalled the macrospore. The tissue surrounding it is called here thenucellus, but because it contains the macrospore it must be themacrosporangium. The two coats or integuments of the ovule areyet short and have not grown out over the end of the macrospore increases in size, forming first a cavity or sacin the nucellus, the embryo sac. The nucleus divides several
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Keywords: ., bookauthoratk, bookcentury1900, bookdecade1900, booksubjectbotany
