86 A Short Talk on Lichens. [Sess. 



sprinkled in early June with the pure white blossom. (See 

 Plate XL) It rapidly spreads by its extensively creeping 

 rhizomes, and the plants found in dry hungry soil have the 

 same starved appearance as those from polar regions. Trien- 

 talis grows, too, in forests other than coniferous, and also on 

 open heaths. Trientalis americana is equally variable, and 

 appears to run into T. europseus. A plant flowered this year 

 at the Eoyal Botanic Garden, Edinburgh, had very deep pink 

 flowers, each one-fourth inch across, but this colouring is not 

 usual. 



The Pyrola are interesting plants, that in some districts are 

 confined to pine-forests, while in others they are not. The 

 differences between the several species native to Britain depend 

 on the length and shape of the style, &c. P. minor is the 

 most frequent. P. rotundifolia has the largest flowers. 



The history of woodland plants has many points of interest : 

 few only have here been touched upon, and those bear but 

 briefly upon their life in Scottish forests. 



[Illustrating the paper, of which the above is an abstract, 

 thirty slides were shown on the screen, depicting various forest 

 plant carpets, &c.] 



VI.— ^ SHORT TALK ON LICHENS, 

 CHLEFLY CLADONL/E. 



By Mr JAMES M'ANDREW. 

 {Read Feb. 24, 1904.) 



In a single paper on such a wide subject as lichens one can 

 only briefly glance at them. Such questions as the Schwen- 

 denerian theory of lichens, their life-history, their distribution 

 and classification, their effect on the earth and on scenery, the 

 purposes they serve in the economy of nature, their economic 

 uses for medicine, for dye-stuff's, for food for man and beast, 

 &c., would each require a paper to itself. As our Society 



