. The structure and development of mosses and ferns (Archegoniatae). Plant morphology; Mosses; Ferns. 494 MOSSES AND FERNS kinds and arranged in four rows, as in most species of Selagi- nella. The branching of the stem is either dichotomous or monopodial. The roots, which are borne in acropetal succes- sion (Bruchmann found also in L. tnundatum adventive roots), branch dichotomously, Hke those of Ispetes. The sporangia are borne singly, in the axils of the sporophylls, which may differ scarcely at all from the ordinary leaves (L. selago, L. lucidulum), (Fig. 287), or the sporophylls are differ
. The structure and development of mosses and ferns (Archegoniatae). Plant morphology; Mosses; Ferns. 494 MOSSES AND FERNS kinds and arranged in four rows, as in most species of Selagi- nella. The branching of the stem is either dichotomous or monopodial. The roots, which are borne in acropetal succes- sion (Bruchmann found also in L. tnundatum adventive roots), branch dichotomously, Hke those of Ispetes. The sporangia are borne singly, in the axils of the sporophylls, which may differ scarcely at all from the ordinary leaves (L. selago, L. lucidulum), (Fig. 287), or the sporophylls are different in form and size from the other leaves and form distinct strobili,. Fig. 287.—Lycopodium, selago. A, Longitudinal section of the stem apex, X120; F, F, young leaves; i, i, initial cells; PI, plerome; B, surface view'of the stem apex, showing the group of initial cells, X260; C, longitudinal section of the root-tip; d, dermatogen; Pb, periblem; PI, plerome; Cal, calyptrogen; h, h, root-hair initials, X120 (all the figures after Strasburger), which are often borne at the end of almost leafless branches (Fig. 282). None of the investigated species of Lycopodium show a definite initial cell at the apex of the stem, and Treub ((2), V) was unable to determine positively whether such a one exists in the embryo. In L. phlegmaria he describes and figures em- bryos, where a single prismatic apical cell is apparently pres- ent, but in others the presence of such a cell was doubtful, and in L. cernuum in no case did he find any evidence of a single initial. The vegetative cone of the mature sporophyte is usually. 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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