60 



as abundant on Lias as on Silurian limestone, and the former, as I recently 

 noticed, is equally at home on the Carboniferous limestone of South Wales. The 

 Yellow wort (Chlora) is as common too on the Wye Cliffs as it is about our own 

 exposed shales. The little Squinancy wort ( Asperula oynanchica), though absent 

 at Malvern, grows on the Cotteswold oolite, but is more luxuriant and plentiful 

 still on the Carboniferous limestone of South Wales. The pretty Bee orchis and 

 O. pyramidalis, devoted as they are to a limestone soil, yet seem to know no 

 difference between the Devonian and the Silurian, and are found as well on the 

 Lias, nay, they flourish even where there is only a thin coating of modern traver- 

 tine on the fundamental rock, as at Tedstone, Herefordshire, on the northern 

 margin of this district. Yet some Orchideae are almost entirely confined to the 

 chalk formation ; while the Cornish heath (Erica vagans) in our own island, revels 

 entirely upon the serpentine of the Lizard, to which rock it is curiously restricted. 

 Nevertheless, some plants are so peculiarly isolated, apparently without reference 

 to soil, that the manner of their location is not easily explainable, Potentilla 

 rupestris in this country never strays from the heights of Craig Breidden* ; and a 

 little plant named Origanum Tournfortii has never been found anywhere else but 

 on the island of Amorgos in the Mediterranean. The Fungus meliteus is also on 

 the rock of Lagos. Other singularly limited plants might be mentioned, as the 

 Handtree of Mexico, and the Cedron of New Granada, Neckera crispa on the Cottes- 

 wolds and Devon ; but nearer home, several mosses, as the Eucalypta, incline 

 only to calcareous soils. Where nature has retained its stern pristine aspect 

 among remote rocks and wild fells "unknown to public view," upon desolate 

 granitic heights and unaltered igneous rocks, it might not be unreasonably ex- 

 pected that characteristic plants would appear independent of their altitudinal 

 character, and this is the case ; but unfortunately they do not remain only there, 

 for as secondary and tertiary rocks, as well as erratic gravel, are nothing more 

 than modified ancient rocks, plants are perpetually migrating, and thus many 

 species are equally found on igneous rocks and on gravel. 



If the more ancient rocks were really elevated above the waves for ages prior 

 to the secondary or mesozoic strata, it would appear perhaps not improbable that 

 vegetation, first appearing upon them, would still remain indicative of the earliest 

 races of plants now in existence. But the migratory nature of plants foils any 

 attempt at demonstration here, since the newest rooks may possess a vegetation 

 more luxuriant than the most ancient, though derivable therefrom ; and Lyell has 

 recorded that Monte Nuovo, near Naples, whose birthday has been historically 

 recorded, bears a more splendid and luxuriant load of groves of Arbutus than any 

 of the older hills around. Hooker and Arnott have suggested that our own flora 

 is altogether derivable from continental sources, though surely rocks of Sedgwick's 

 Cambrian system must be as ancient as any in Europe. One plant only, Vicia 

 laevigata, appears in our flora as having been found nowhere else in the world 

 than. Weymouth. 



Perhaps, however, the humble lichen tribe give some indications as remark- 

 able, if not more so, than the phanerogamous or flowering plants. These are so 



* In Montgomeryshire 



