524 DicJde's Flora Abredone?iszs. 



The examples are, Orchis mascula, which occurs at the Bridge of Don, and 

 upon the coast toward Stonehaven, at both which places the old red sand- 

 stone predominates ; the other is a fern, Asplenium Trichomanes, which has 

 only yet been detected upon serpentine rocks at Belhelvie. This last plant is 

 found with Asplenium Adiantum nigrum ; but this species is frequent on the 

 coast from Aberdeen to Stonehaven, upon several different kinds of rock. We 

 believe that vegetation is less affected by the chemical nature of the rock than 

 by its particular variety : by this last is meant its greater or less capability of ab- 

 sorbing or reflecting heat, its tendency to become decomposed, and its power of 

 attracting, absorbing, and permitting the passage of moisture.* In noting the 

 connexion between rocks and plants, we must observe whether the soil, in 

 which the former grow, has been produced by the debris of the latter, or 

 transported from some other part. It is stated in a paper, in the 5th volume 

 of Mem. of the Wernerian Society, that, in Yorkshire, the Astragalus h3'po- 

 glottis and Helianthemum vulgare are confined to the chalky districts : there 

 is no chalk in this neighbourhood, and these plants are abundant near granite, 

 gneiss, and other rocks. In the same paper, Pinguicula vulgaris and Empe- 

 trum nigrum are said to occur on sandstone. With us, the former is found 

 indifferently over other rocks ; and the latter, which ranks among our common 

 plants, we have seen growing in peat, gravel, and, at Belhelvie, in pure sand, 

 along with Ammophila arundinacea, Carex arenaria, and others. 



" Cromer of Hanover says, " When the proportion of clay, in any soil, does 

 not exceed sixty per cent, Trifolium arvense may be found ; if the clay reach 

 eighty per cent, you will search for it in vain.' Until every botanist becomes 

 also a practical chemist, we cannot expect to arrive at such precision as this 

 regarding every individual species." 



Of the vegetation, a number of species are enumerated peculiar 

 to different regions. 



" The surface of the country is interspersed with marshes or bogs, lakes or 

 lochs, woods and moors, and these are very productive of the plants pro- 

 ducing the varieties of peat named by M'Culloch {Ed. Phil. Journ. vol. ii.), 

 mountain, marsh, forest, and lake peat. In our marshes and bogs, the plants 

 which mostly contribute to the formation of this very important natural pro- 

 duction are, several species of Carex, as C. dioica, C. puhcaris, C. ampullacea, 

 C. curta, and sometimes C. teretiuscula ; also Erica Tetralix, Eriophorura 

 angustifolium, and E. vaginatum ; also various species of Juncus, Menyanthes 

 trifoliata, Caltha palustris, Pedicularis sylvatica and palustris, Comarum palus- 

 tre, and, more rarely, Drosera anglica, Schoenus nigricans, and many others. 

 In such places, and also on the borders of lochs, we find what are called 

 quaking bogs, consisting of a semifluid mass of peat, the surface of which is 

 covered with vegetation. The adventurous botanist, whose ardour leads him 

 into such situations, entirely owes his safety to the matted roots and stems of 

 the different plants. 



" In lochs, the following plants principally contribute to the formation of 

 peat: — Scirpus lacustris, Arundo Phragmites, the yellow and Whitewater 

 lilies, Sparganium natans, Phalaris arundinacea, &c. ; and about their edges, 

 in shallower water, Littorella lacustris, Scirpus setaceus, Peplis Portula, and, 

 more rarely (in this district), Subularia aquatica, Pihilaria globulifera. Lobelia 

 Dortmanna, Utricularia intermedia, and others. The variety called mountain 

 peat is produced in drier places, and is of a loose texture; the different 

 heaths, the crowberry (Empetrum nigrum), various species of Carex, as 

 C. binervis, C. pilulifera, Nardus stricta, and many grasses and others, all 



* This opinion was maintained by the late talented author of the Northern 

 Flora, who published a paper on this subject, some years ago, in Loudon's 

 Magazine of Natural History. 



