. The structure and development of mosses and ferns (Archegoniatae). Plant morphology; Mosses; Ferns. 266 MOSSES AND FERNS CHAP. sieve-tubes consist of a thin parietal layer of protoplasm in which numerous nuclei are imbedded. Little glistening glob- ules are also found, especially close to the openings of the pores of the sieve-plates. The lamina of the sterile segment of the leaf is composed of a spongy green mesophyll, more compact on the upper sur- face. The epidermal cells show the wavy outlines characteristic of the broad leaves of other Ferns, and develop stomata only upon the lower sid
. The structure and development of mosses and ferns (Archegoniatae). Plant morphology; Mosses; Ferns. 266 MOSSES AND FERNS CHAP. sieve-tubes consist of a thin parietal layer of protoplasm in which numerous nuclei are imbedded. Little glistening glob- ules are also found, especially close to the openings of the pores of the sieve-plates. The lamina of the sterile segment of the leaf is composed of a spongy green mesophyll, more compact on the upper sur- face. The epidermal cells show the wavy outlines characteristic of the broad leaves of other Ferns, and develop stomata only upon the lower side of the Fig. 146.—Botrychium Virginianum. A, Longitudinal; B, transverse sections of the root apex, X200; pi, plerome. The Root The roots arise singly at the bases of the leaves, and in older plants branch monopodially. Like those of Ophioglossum they have no root-hairs, but the smooth surface of the younger roots becomes often strongly wrinkled in the older ones. Sec- tions either transverse or longitudinal, through the root tip, when compared with those of Ophioglossum, show a very much greater regularity in the disposition of the cells. This is less marked in B. ternatum, and probably an examination of such forms as B. simplex will show an approximation to the condi- tion found in Ophioglossum, although Holle's figure of B. luna-. 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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