. The structure and development of mosses and ferns (Archegoniatae). C. Fig. 212.—a, Pinnule of Gleichenia dichotoma, showing the position of the sori (j),X4; B, ventral; C, dorsal view of the ripe sporangium, X85. young sporangia arise as small conical outgrowths. Each spo-rangial outgrowth undergoes a series of regular segmentationsresulting in a central, nearly tetrahedral, sporangial cell, fromwhich successive segments are cut off which give rise to theshort, massive stalk of the sporangium. Finally a periclinalwall is formed resulting in the archesporium. The further de-velopment is much
. The structure and development of mosses and ferns (Archegoniatae). C. Fig. 212.—a, Pinnule of Gleichenia dichotoma, showing the position of the sori (j),X4; B, ventral; C, dorsal view of the ripe sporangium, X85. young sporangia arise as small conical outgrowths. Each spo-rangial outgrowth undergoes a series of regular segmentationsresulting in a central, nearly tetrahedral, sporangial cell, fromwhich successive segments are cut off which give rise to theshort, massive stalk of the sporangium. Finally a periclinalwall is formed resulting in the archesporium. The further de-velopment is much like that of Osmunda, except that the inner ofthe two layers of tapetal cells become very large and their nuclei THE HOMOSPOROUS LEPTOSPORANGIATJE 371 may divide (Fig. 211). At this stage there is a marked re-semblance to the sporangium of Angioptcris, and Bower callsattention to the similarity in form between the sorus of Gleich-enia and that of the Marattiacese. The walls of the innertapetal cells are finally absorbed. The number of sporogenouscells is large,
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Keywords: ., bookauthorcampbelldouglashought, bookcentury1900, bookdecade1910
