46 YORKSHIRE NATURALISTS' UNION. 



others sandstone rocks, but which elsewhere do not occur 

 together. The botanical characters of granite, basalt and slate 

 are however all different when they have a fair chance of 

 showing themselves, which is not the case with the two 

 former in the North of England. It may perhaps be affirmed 

 that in its botanical characters granite approaches the arenace- 

 ous, basalt the calcareous, and slate the argillaceous group of 

 strata. 



The cryptogamic flora of the igneo-metamorphic rocks is 

 very rich and varied and contains several abundant and character- 

 istic species. 



The following species are chiefly found on rocks of this 

 class : — 



Alchemilla alpina. i Hedwigia ciliata. 



Asplenium septentrionale. 

 Cryptogramme crispa. 

 Grimmia (several species). 



Parmelia conspersa. 

 Lecanora ventosa. 

 Lecidea geographica. 



It is also to be noticed that the plants of alpine regions are 

 frequent on these strata, descending to a comparatively low level. 

 On a calcareous soil, on the other hand, mountain plants do not 

 appear until we reach a considerable elevation, while the ordinary 

 species of lowland districts reach a higher level on limestone than 

 on either of the other kinds of rock. 



2. Calcareous. — The flora of calcareous soils is numerous 

 in species and rich in characteristic forms. The special feature 

 of the vegetation of such soils is the closely-matted green carpet 

 of herbage with which the surface is covered. Out of the large 

 number of species more or less peculiar to limestone soils the 

 following may be mentioned : — 



Viola hirta. 

 Arabis hirsuta. 

 Draba verna. 

 Reseda lutea. 

 Helianthemum vulgare. 



Geranium lucidum. 

 Genista tinctoria. 

 Anthyllis vulneraria. 

 Spiraea Filipendula. 

 Poterium sanguisorba. 



Trans.y.N.U., 1878. Series E 



