. Elementary botany. Botany. Kig. 249. Base of leaf of isoetes, showing sporangium with macrospores. (isoetes en- gelmannii.). Fig. 250. Section 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 sporangium. Beside the spores on the inside of the sporangium, there are strands of sterile tissue which extend across the cavity. This is peculiar to isoetes of all the members of the class of plants to which the ferns belong, but it will be remembered that ster


. Elementary botany. Botany. Kig. 249. Base of leaf of isoetes, showing sporangium with macrospores. (isoetes en- gelmannii.). Fig. 250. Section 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 sporangium. Beside the spores on the inside of the sporangium, there are strands of sterile tissue which extend across the cavity. This is peculiar to isoetes of all the members of the class of plants to which the ferns belong, but it will be remembered that sterile strands of tissue are found in some of the liverworts in the form of elaters. 399. The spores of isoetes are of two kinds, small ones (microspores) and large ones (macrospores), so that in this respect it agrees with selaginella, though it is so very different in other respects. When one kind of spore is borne in a sporan-. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Atkinson, George Francis, 1854-1918. New York, H. Holt


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