HIDDEN MARRIAGES 529 



most cases characterized by great beauty and delicacy of form. The 

 leafy Scale-mosses are of 

 a more delicate structure 

 than most Mosses, their 

 leaves being filmy and al- 

 most transparent, which is 

 due to the cells being larger 

 and the cell-walls thinner. 

 The stems are more ad- 

 dicted to creeping, and the 

 leaves are mostly all in 

 the same plane. They are 

 shade and moisture-loving 

 plants, and must be sought 

 in the damp shade of woods, 

 on the rocks and margins 

 of mountain streams, the 

 banks of ditches, the 

 swampy borders of pools. 

 As an example of these 

 foliose Crystalwortswe give 

 a figure of Plagiochila a- 

 plenioides (fig. 668), a 

 species that may be found 

 growing at the base of 

 tree trunks in moist woods. 

 The toothed leaves are 

 arranged pinnately along 

 the two sides of the stem, 

 and the fruit is borne at 

 the extremity of the 

 branches. As drawn, the 

 leaves show a central 

 division or fold, and this 

 must not be taken for a 

 nerve, for in all the Crystal- 

 worts the nerve, so con- 

 spicuous a feature in the 

 leaves of Mosses and higher 

 plants, is entirely wanting. 

 Of the two fruits shown, 

 that to the right has the 



sporange intact ; that to the left has split into its 

 spread out to release the spores. 

 n16 



Photo by] [E. Step. 



FIG. 673. BEARD Moss (Usnea dasypoga). 



A. delicate grey Lichen that hangs in lengths of a foot or more from old 

 forest trees. 



four valves which 



