FIELD BOOK OF PONDS AND STREAMS 



germinate into minute filaments, the protonemata, which make 

 little green patches upon the earth from which the familiar 

 moss plants ultimately grow. 



Some moss plants bear female organs, the archegonia, equiv- 

 alent to the ovaries of an animal ; others bear male organs, the 

 antheridia, equivalent to spermaries. In the antheridia there 

 are thousands of minute male cells some of which subsequent- 

 ly fertilize egg-cells borne upon the female plants. The 

 familiar capsule of spores arises from a fertilized egg and is 

 always borne on a female plant. The spores from the cap- 

 sule mature and are scattered upon the ground and without 

 fusing with any other cell develop into plants which represent 

 the asexual generation. Each moss plant is of a different sex, 

 some bearing male, others bearing female organs. Such male 

 and female plants occur in every other generation and hence 

 are known as the sexual generation. 



Water Mosses — FontinalacecE 



The water mosses are a family of slender, very dark green 

 mosses with long streamer-like branches, which wave from 

 the stones in swift currents, or grow upon stones and wood on 

 the edges of ponds. 



Dichelyma. — The yellowish green masses of Dichelyma 

 grow commonly on rotting sticks in and around the edges 

 of ponds and in swampy places. The plants of Dichelyma 

 capillaceuni (Fig. 54), our only common species, are yellow 

 toward the tips and brownish or black below. The stems 

 are slender, often over three inches long, branched, and usually 

 matted together. The spore capsule matures in summer, its 

 short stem or seta protruding from the leaves that wrap close- 

 ly around it. 



Occurrence. — New Brunswick to Ontario and Pennsylvania. 

 Fruits in summer. 



Fountain mosses, Fontinalis. — The fountain mosses form 

 dense, dark, olive green covers upon the stones of swift brooks, 



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