HABIT AND MANNER OF GROWTH 



Mosses have certain ways of growing and of branch- 

 ing that are important generic characteristics and these 

 should be noticed when specimens are collected for 

 determination. 



There are two chief types of growth by which all 

 mosses fall naturally into two main divisions. In one, 

 the acrocarpous mosses, which often form a deep, 

 thick growth, the stem is typically erect (Plate I, 

 Fig. i), not branched or with only a few branches, and 

 the fruit is borne at the tip of the stem, sometimes ap- 

 pearing lateral by the new growth of the plant. (Plate 

 I, Figs. 2, 3.) In the second type, the pleurocarpous 

 mosses, which often form thin, fiat, tangled mats, the 

 stem is generally prostrate (Plate I, Fig. 4), or ascend- 

 ing (Plate I, Fig. 5), erect in only a few cases, much 

 branched, and the fruit is borne on the side of the 

 stem. 



The plants may be scattered singly or may grow 

 more or less crowded together. Deep mossy mats are 

 sometimes formed when plants with erect or ascending 

 stems grow close together and the new annual growth 

 is added to that of the previous year. Thin flat mats 

 occur when the plants are prostrate or creeping and 

 the stems and branches continue to spread and inter- 

 weave. In some genera, rounded cushions are formed 



