File:The structure and development of mosses and ferns (Archegoniatae) (1918) (14804835253).jpg

Title: The structure and development of mosses and ferns (Archegoniatae)
Year: 1918 (1910s)
Authors: Campbell, Douglas Houghton, 1859-1953
Subjects:
Publisher: New York, Macmillan
Contributing Library: The LuEsther T Mertz Library, the New York Botanical Garden
Digitizing Sponsor: The LuEsther T Mertz Library, the New York Botanical Garden

View Book Page: Book Viewer
About This Book: Catalog Entry
View All Images: All Images From Book
Click here to view book online to see this illustration in context in a browseable online version of this book.

Text Appearing Before Image:
ceablein the male plants. There is often, under these conditions,a development of leaf-like marginal lobes. This excessivevegetative development of the thallus is accompanied by amarked diminution in the number of the sexual organs.(Campbell (17)). Geothallus. Evidently closely allied to Sphcerocarpus is a remarkableLiverwort, as yet found only near San Diego, in Southern Ill THE JUNGERMANNIALES 83 California (Campbell (18)). Geothallus tiiherosiis (Figs.34, 35), differs from Sphccrocarpus in its much larger size,the development of leaf-like organs, much like those of Fos-somhronia and by the very much larger size of the spores.There are also some minor differences in the structure of thereproductive organs, the antheridia having a more massivepedicel than that of Sphccrocarpus. The plants are perennial,and at the end of the growing season the younger parts of thethallus become changed into a tuber with a thick black cover-ing. The tubers are buried in the earth during the dry season.
Text Appearing After Image:
n Fig. z^.—Geothallus tuberosus. A, Archegonium, X200; B, ripe antheridium, X about65; C, a four-celled embryo, X200; D, ripe spore; E, sterile cells, X100. The apex of the shoot persists and resumes growth as soonas the conditions are favorable. Riella. The peculiar genus Riella (Goebel (17), Leitgeb (7), Por-sild (i)), while it closely resembles Sphccrocarpus in the struc-ture of the reproductive organs and sporophyte, differs verymuch in the habit of the gametophyte. Until very recently(Howe and Underwood (3)), all the species known werefrom the regions adjacent to the Mediterranean, but one specieshas since been found in the Canary Islands, and another in theUnited States. They are all submersed aquatics. The thal-lus shows a cylindrical axis, from which grows a thin vertical 84 MOSSES AND FERNS CHAP. dorsal lamina or wing, which may be more or less spirallyplaced, owing to torsion of the axis, but this torsion was muchexaggerated in the early figures of the original species, R.

Note About Images