Elementary botany . Fig- 337-Base of leaf of isoetes,showing sporangium withmacrospores. (Isoetes en-gelmannii.). Fig. of plant of Isoetes engelmanii, showing cup-shaped stem, and longitudinal sections of the sporan-gia in the thickened bases of the leaves. ure from the other portions of the leaf. This is a the spores on the inside of the sporangium, there arestrands of sterile tissue which extend across the cavity. This ispeculiar to isoetes of all the members of the class of plants towhich the ferns belong, but it will be remembered that sterilestrands of tissue
Elementary botany . Fig- 337-Base of leaf of isoetes,showing sporangium withmacrospores. (Isoetes en-gelmannii.). Fig. of plant of Isoetes engelmanii, showing cup-shaped stem, and longitudinal sections of the sporan-gia in the thickened bases of the leaves. ure from the other portions of the leaf. This is a the spores on the inside of the sporangium, there arestrands of sterile tissue which extend across the cavity. This ispeculiar to isoetes of all the members of the class of plants towhich the ferns belong, but it will be remembered that sterilestrands of tissue are found in some of the liverworts in the formof elaters. 591. The spores of isoetes are of two kinds, small ones(microspores) and large ones (macrospores), so that in thisrespect it agrees with selaginella, though it is so very different inother respects. When one kind of spore is borne in a sporan- QUILLWORTS. 291 gium usually all in that sporangium are of the same kind, so thatcertain sporangia bear microspores, and others bear it is not uncommon to find both kinds in the same sporan-giu
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Keywords: ., bookauthoratk, bookcentury1900, bookdecade1900, booksubjectbotany
