. Botany; principles and problems. Botany. THE PTERIDOI'IIYTA 339 Equisetineae or Horsetails.—This vory distinct class consists of but one order, tlie Equisetales, and this of but the single genus Equisetum, the horsetails or scouring rushes (Fig. 214). Some of its species grow in dry sterile soil and others in marshy situa- tions. From a perennial rootstock arise the very characteristic stems, which are jointed, ridged, and hollow. Leaves are repre-. Fio. 213.—Isoetes. A, general appearance of the plant. B, a megaspore. C, a microspore. sented merely by a circle of scales which surround the s
. Botany; principles and problems. Botany. THE PTERIDOI'IIYTA 339 Equisetineae or Horsetails.—This vory distinct class consists of but one order, tlie Equisetales, and this of but the single genus Equisetum, the horsetails or scouring rushes (Fig. 214). Some of its species grow in dry sterile soil and others in marshy situa- tions. From a perennial rootstock arise the very characteristic stems, which are jointed, ridged, and hollow. Leaves are repre-. Fio. 213.—Isoetes. A, general appearance of the plant. B, a megaspore. C, a microspore. sented merely by a circle of scales which surround the stem at each joint or node, the green stems carrying on most of the pro- cess of photosynthesis. Aside from the large central air space, a smaller one occurs just inside each furrow in the stem (Fig. 215). Opposite each ridge is a small and very poorly developed fibro- vascular bundle, the stoutness and strength of the stem being due chiefly to the layers of heavy-walled sclcrenchyma which it. 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 Sinnott, Edmund Ware, 1888-. New York, McGraw-Hill
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Keywords: ., bookcentury1900, bookdecade1920, booksubjectbotany, bookyear1923
