ORTHOTRICHACEAE 49 



E. streptocarpa Hedw. "On limestone rocks, Sussex Co., 

 N. J.," Muse. App. 175; Swartswood, N. J. ; Wiegmann. 



GROUP 2. DIPLOLEPIDEAE 



Peristome double, the plates of the outer side of the teeth 

 (outer peristome) in two rows, separated by a zigzag median 

 line; inner side of teeth of a single row of plates. 



Inner peristome thin and membranous, made up of the inner 

 walls of the same cells whose outer walls formed the inside 

 plates of the teeth. The teeth of the inner peristome are known 

 as segments, and are usually 16, alternating with the teeth, 

 somewhat keeled, usually arising from a basal membrane \ to 

 x /2 the height of the teeth, and in the highest development 

 separated by 1-3 hair-like cilia of varying lengths. The seg- 

 ments may be opposite the teeth and without basal membrane 

 or cilia as in Funaria. The segments themselves may be re- 

 duced to a mere filament, as in Orthotrichum. The entire inner 

 peristome may be lacking in degenerate types, as in some 

 species of the Bartramiaceae, or even the entire peristome may 

 be lacking, as in Physcomitrium . 



Subgroup 1. Acrocarpeae 



Sporophyte terminal from erect, or nearly erect stems, some- 

 times becoming lateral by innovations. In these respects the 

 plants of this subgroup are like most of those of the preceding 

 families. 



Family 13. ORTHOTRICHACEAE 



This family somewhat resembles the Grimmiaceae, but nearly 

 always grows on trees. The plants are small, rarely reaching 

 an inch in height and usually much shorter, blackish or brown- 

 ish green below; nearly always growing in tufts or cushions. 

 The leaves are oblong- or linear-lanceolate and usually very 

 hygroscopic; cells of the upper part hexagonal to rounded- 

 hexagonal, thick-walled and often papillose; lower cells oblong 

 to rectangular, rarely papillose, thinner walled in most cases, 

 and often hyaline; costa single, strong. The calyptra is nearly 

 always hairy and the capsules often immersed, with very distinct 

 longitudinal wrinkles when dry and empty. The peristome usually 



