. Botany for high schools and colleges. Botany. 388 BOTANY. spores, while the iuterior ones contain microspores. Both macrospcres and microspores are produced in irreat numbers in the sporangia. The Quillworts are for tlie most part a(]uatic plants ; they are found chiefly in the nonh temperate and warm regions. The species, of. Fig. 280.—Germination of the microspores of Isoetes lacustris. ji, a microspore, side view. B, the same, ventral view ; the spore contents have divided into a few cells, of which v in each figure represents the rudimentary prothallium ; j3^ ^ are the ventral, aud J (J
. Botany for high schools and colleges. Botany. 388 BOTANY. spores, while the iuterior ones contain microspores. Both macrospcres and microspores are produced in irreat numbers in the sporangia. The Quillworts are for tlie most part a(]uatic plants ; they are found chiefly in the nonh temperate and warm regions. The species, of. Fig. 280.—Germination of the microspores of Isoetes lacustris. ji, a microspore, side view. B, the same, ventral view ; the spore contents have divided into a few cells, of which v in each figure represents the rudimentary prothallium ; j3^ ^ are the ventral, aud J (J the dorsal cells. C, a side view of microspore ; the four cells, R l3, tJj S^ have disappeared, and spermatozoids have formed. D, ventral view of C; a to /, development of spermatozoids. e and/ X 700, the others X 580,—After Millardet. which there are from forty to fifty or more, all belong to the single genus Isoetes;"^ we have representations of about fourteen within the United States. Two species of Isoetes occur as fossils in the Tertiary (Miocene). * The North American species of Pteridophytes are well described in "Our Native Ferns and their Allies," by L. M. Underwood. (Holt, •). 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 Bessey, Charles Edwin, 1845- [from old catalog]. New York, H. Holt and company
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