Mosses and Lichens 



springs and rivulets, or even floating on water. The genus is an 

 easy one to recognise and the plants form an attractive feature 

 of one's walk through woods or over fen-land. 



The name Sphagnum (Greek o-^cryvo?) was used by the an- 

 cient botanists Theophrastus, Dioscorides, and Pliny to indicate 

 certain non-flowering plants. The name was restricted to a 

 more limited use in 1719 by Johann Dillenius, a German, who 

 was the first professor of botany 

 at Oxford. 



Cttt. 



Leaf magnified to show large cells with 

 perforations and spiral thickenings and 

 small cells with leaf-green grains. 



Sphagnum cymbifotium. 



Surface view of leaf cells. 



The plants are soft and weak-stemmed mosses, generally of 

 large size, white or yellow, light green or sometimes red. The 

 stems appear almost simple with clusters of branches at the 

 summit and on the sides ; the branches at the summit are 

 grouped to form a dense rosette (capitulum), while each side 

 cluster (fascicle) consists of from 2 to 7 or more branches, some 

 spreading and some appressed to the stem. A cross section of 

 the stem shows three zones of cells the outer (cortex) of large 

 loose cells, the central of pithy cells and the intermediate of 

 woody cells. 



The leaves are translucent, without veins, and consist of a 

 single layer of two kinds of cells : (i) Large colourless and 

 transparent cells (utricles), generally perforated and lined with 



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