. The structure and development of mosses and ferns (Archegoniatae). Plant morphology; Mosses; Ferns. 332 MOSSES AND FERNS CHAP. parenchyma, and in the phloem the sieve-tubes are accompanied by bast parenchyma. Outside the phloem is a layer of cells, which may be double in some places, and which usually contain a good deal of starch. According to Strasburger ((ii). Vol. 3, p. 446) these cells do not constitute a true pericycle, but belong to the cortex. They are sister-cells of the endodermis, which is thus, not the inner- most cortical layer, but the next but one. The endodermal cells show th
. The structure and development of mosses and ferns (Archegoniatae). Plant morphology; Mosses; Ferns. 332 MOSSES AND FERNS CHAP. parenchyma, and in the phloem the sieve-tubes are accompanied by bast parenchyma. Outside the phloem is a layer of cells, which may be double in some places, and which usually contain a good deal of starch. According to Strasburger ((ii). Vol. 3, p. 446) these cells do not constitute a true pericycle, but belong to the cortex. They are sister-cells of the endodermis, which is thus, not the inner- most cortical layer, but the next but one. The endodermal cells show the characteristic thickenings on their radial Fig. 184.—Woodwardia radicans. A, Tracheids, t, and wood-parenchyma, par., from the rhizome, X225 (about); B, longitudinal section of two tracheids, more strong- ly magnified; C, section of the wall between two tracheids; D-F, sieve tubes- The Leaf While the leaf in a few of the Leptosporangiatse is simple, in much the larger number it is compound, either dichotomously branched (Adiantum pedatum) or more commonly pinnately divided. Owing to the great irregularity of the divisions and slow formation of new segments in the stem apex, it is exceed- ingly difficult to determine positively whether each segment of; the stem apex produces a leaf, but this seems probaHe. The leaf appears as a blunt conical emergence, whose apex is occu- pied by a single large apical cell, which in nearly all forms examined is wedge-shaped and forms two rows of segments. As the leaf grows it assumes the form of a flattened cone with a. 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 Campbell, Douglas Houghton, 1859-1953. New York, The Macmillan Company;
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