Mosses and Lichens 



vein extending to near the apex ; margin minutely blunt-toothed. 



Habit of flowering. Male and female flowers on separate 

 plants (dioicous). 



Veil (calyptra). Split up one side. 



Spore-case. Exserted, oblong, yellow-brown, slightly con- 

 stricted under the mouth when dry. 



Spore-case 



without 

 teeth. 



Spore-case 

 with veil. 

 Gymnostomum calcareum. 



Leaves. 



Pedicel. \ to f of an inch long. 



Lid (operculum). Base conical ; beak awl-like. 



Teeth (peristome). None. 



Annulus. Short and persistent. 



Spores. Rare, mature in summer. 



Distribution. Universal. 



Gymnostomum curvirostrum, Hedw. 



Habit and habitat. This moss is found on limestone rocks 

 and on deposits of carbonate of lime about springs 

 and streams. The plants obtain the carbonic acid 

 gas (CO 2 ) which they need, from bicarbonate of 

 lime which is dissolved in the surrounding water. 

 By decomposition of the bicarbonate of lime [H, 

 Ca (CO 3 ) 2 ], which is soluble in water, the mono- 

 carbonate of lime (Ca CO 3 ), which is insoluble in 

 water is precipitated in the form of incrustations 

 upon the leaves and stems of the moss, so that 

 in time a very appreciable deposit of limestone 

 is made.* 



Name. From the Latin curvus, curved, and rostrum, a beak. 



G. curvirostrum. 

 with long beak. 



*See page 17. 



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