HABIT AND MANNER OF GROWTH 13 



when a number of plants grow together in separated 

 tufts instead of spreading over any extent of surface. 



The stems may be not branched at all or slightly 

 branched by forking (Plate II, Fig. i), or with numer- 

 ous lateral branches arranged pinnately (Plate II, 

 Fig. 2), bipinnately (Plate II, Fig. 3), tripinnately 

 (Plate II, Fig. 4), irregularly (Plate II, Fig. 6), in 

 clusters (Plate II, Fig. 7), or like the branches of a tree 

 (Plate II, Fig. 5). 



Sometimes the primary stem is creeping and the 

 secondary stems erect or ascending, more or less 

 branched (Plate II, Fig. 8). In this case, care must be 

 taken to separate the plants and not to mistake a 

 pleurocarpous moss with prostrate stem and erect 

 branches (Plate II, Fig. 8) for an acrocarpous moss 

 with erect stem (Plate I, Fig. i). 



The pleurocarpous mosses, usually creeping or pros- 

 trate, grow in tangled mats with interwoven stems 

 and branches so that no great length can be easily 

 separated, while individual plants of the acrocarpous 

 mosses, growing erect, are easily separated. Two or 

 more kinds of mosses are often found growing together. 

 When plants with erect stems (acrocarpous mosses) are 

 mixed, it is not difficult to separate them, especially if 

 the leaves of the different species are distinctly unlike; 

 but one prostrate species (a pleurocarpous moss) may 

 grow on top of another of similar growth quite con- 

 cealing it, or the stems and branches of both mosses 

 may grow together on the surface, sometimes so inter- 



>v 



