. The structure and development of mosses and ferns (Archegoniatae). Plant morphology; Mosses; Ferns. VIII MARATTIALES" 285 The proihallium does not die immediately after the young sporophyte becomes independent, but may remain aHve for several months afterwards, much as in Botrychium. The first tracheary tissue arises at the junction of the bun- dles of the cotyledon, stem, and root. These primary tracheids are short and their walls are marked with reticulate thickenings. From this point the development of the tracheary tissue, as well as the other elements of the bundles, proceeds towar
. The structure and development of mosses and ferns (Archegoniatae). Plant morphology; Mosses; Ferns. VIII MARATTIALES" 285 The proihallium does not die immediately after the young sporophyte becomes independent, but may remain aHve for several months afterwards, much as in Botrychium. The first tracheary tissue arises at the junction of the bun- dles of the cotyledon, stem, and root. These primary tracheids are short and their walls are marked with reticulate thickenings. From this point the development of the tracheary tissue, as well as the other elements of the bundles, proceeds toward the apices of the young organs. The formation of the secondary tracheids is always Fig. 157.—A, Young sporophyte of Danaea simplicifolia, still attached to the gameto- phyte, pr; X3; B, an older sporophyte of the same species; C, gametophyte of Angiopteris evecta^ with the young sporophyte. (A, B, after Brebner; C, after Farmer.) Jeffrey (3) states that in the young sporophyte of several species of Dancsa examined by him, the stele has the form of a tube with both internal and external endodermis and phloem. Both internal endodermis and phloem tend to disappear in the later-formed part of the stem. The tubular central cylinder is interrupted by the foliar gaps, and later there are formed medullary vascular strands, and the vascular system gradually assumes the very complicated form met with in the older sporophyte. Brebner (3) states that in Dancea simplicifolia the. 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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