. The structure and development of mosses and ferns (Archegoniatae). Plant morphology; Mosses; Ferns. THE HOMOSPOROUS LEPTOSPORANGIATJE 365 The Sporangium The sporangia in Osmunda are produced upon sporophylls that closely resemble those of Botrychium or Helminthostachys, but in Todea they occur upon the backs of the leaves, as in most Ferns. In structure and development they are intermedi- ate between the true leptosporangiate type and the eusporangi- ate. So far as they have been investigated they all correspond very closely. The origin of the sporangia is almost identical with that in Botry
. The structure and development of mosses and ferns (Archegoniatae). Plant morphology; Mosses; Ferns. THE HOMOSPOROUS LEPTOSPORANGIATJE 365 The Sporangium The sporangia in Osmunda are produced upon sporophylls that closely resemble those of Botrychium or Helminthostachys, but in Todea they occur upon the backs of the leaves, as in most Ferns. In structure and development they are intermedi- ate between the true leptosporangiate type and the eusporangi- ate. So far as they have been investigated they all correspond very closely. The origin of the sporangia is almost identical with that in Botrychium, and more than one cell may take part. Fig. 207.—A, Pinnule of a fertile leaf of Todea (Leptopteris) hymenophylloides, Xa; B, fertile pinnule of Osmunda Claytoniana, X3; C-E, three views of the ripe sporangium of O. cinnamomeaj X40; F, G, sporangia of Todea hymenophylloides, X40; r, annulus. in their formation (Bower (ii); Goebel (17)). Bower says: "In all cases, however, one cell distinctly takes the lead, and this we may call the initial cell (Fig. 206, A); but the arrangement of its division wall does not, as in the true lepto- sporangiate Ferns, conform to any strict plan; the initial cells are oblong, seen in vertical section, and the first divisions are longitudinal, so as to meet the basal wall: both in the segment thus cut off and in the central cell, periclinal or sometimes oblique divisions may take place, so that a considerable bulk of. 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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