72 FLOWERLESS PLANTS 



and this it is able to do from the air or from 

 actual drops of rain or dew. 



Some of the mosses, notably the species of 

 Polytrichum, have special means of guarding 

 against undue loss of moisture. The great 

 cushions of Polytrichum will present a very 

 different appearance during the dry weather 

 which so often comes with March from that 

 evinced during the time when there is plenty of 

 moisture about. If we examine a single stem 

 we shall find that instead of the leaves being 

 spread out, they are drawn up closely to the 

 stalk. In this way the exposed surface is very 

 much reduced, and the rapid evaporation of 

 moisture will be checked. These Hair Mosses 

 are astonishingly sensitive to a dry air, as can 

 be readily proved. If we take a bunch of the 

 stalks home with us during moist weather and 

 place this in an ordinary room, it wiU be found 

 that quite soon the leaves close up, and so 

 rapidly will this take place that it is often 

 difficult to examine the plant indoors. In addi- 

 tion, a certain number of the Hair Mosses 

 have filmy processes which cover the entire 

 green part of the leaf. 



Happily some of the most distinctive mosses 



