White Mosses 



Lid (operculum). Conical, with a long beak. 

 Teeth (peristome). Red, sixteen, each cleft into two slender 

 segments with numerous cross-bars; inclined when dry. 

 Annulus. One or two rows of large cells. 

 Spores. Mature in December. 

 Distribution. Universal. 



WHITE MOSSES 



Genus LEUCOBRYUM, Hampe 



The white mosses are found in conspicuous greenish-white 

 cushions about the roots of trees, in woods and on the borders 



of swamps. The moist 

 cushions are soft and 

 spongy and decidedly 

 greener than the dry, which 

 are so brittle that they can 

 be readily crumbled to 

 dust; and so colourless that 

 they lead one to think they 

 are parasitic or sapro- 

 phytic plants. The change 

 from brittle to soft is due 

 to large cells in the leaves 

 being filled alternately with water and air. 



The pale colour is due to the fact that the cells which contain 

 leaf-green and active cell-contents are relatively small and are 

 hidden between transparent cells many times as great. This 

 arrangement of the cells is a contrivance for protecting the 



-ilo.de 



Cells Con- 

 ta. i. r\. I wq ltu.4- 

 -- * 



.Cells cont <xcn- 

 0-i.r or 



Leucobrywm vulgare. Cross-section of leaf. 



161 



