IN ASCENDING REGIONS. 59 



the one in an ascending, and the other in a descending 

 range, they will be considered common to the two regions. 

 Some latitude must be allowed in these instances, and 

 very slight trespasses into an adjacent region be over- 

 looked. Such will usually be found in connection with 

 the efflux of cold springs, the spray of descending streams, 

 the shade of rocks, or other circumstances causing a local 

 deterioration of the climate to which the plant is ex- 

 posed. 



The usual or prevalent vegetation of the plains is that 

 most familiar to us, and generally known as weeds or 

 wild flowers. The oak and ash form the principal trulj r 

 indigenous forest trees of the region;, to which some of 

 the larger willows may be added. The beech, limes and 

 elms (excepting Ulmus montana) are scarcely admitted 

 to be hereditary Britons. The chesnut and sycamore, 

 frequently planted, have a still more doubtful title. 

 Ulmus montana and Betula alba, seen in many places 

 here, are more characteristic of the uplands. Among 

 other arborescent species, sometimes growing to trees, 

 sometimes forming large shrubs, may be mentioned, as of 

 common occurrence, Crataegus Oxyacantha, Ilex Aqui- 

 folium, Corylus Avellana, Alnus glutinosa, Sambucus 

 nigra, and Pyrus Malus, with species of Salix. Acer cam- 

 pestre is frequent in the south of England, but dwindles 

 off northward both in size and frequency. Rhamnus 

 catharticus and Euonymus europaeus are locally plentiful, 

 and chiefly in the south and middle of England. A great 

 portion of the underwood, hedgerows, and coppices are 

 composed of the smaller-sized trees just enumerated, 

 together with the various species of Rosa, Rubus, and 

 Salix, Prunus spinosa, Viburnum Opulus, and Lonicera 

 Periclymemum. Cornus sanguinea, Viburnum Lantana, 

 Ligustrum vulgare, are local, and more plentiful in the 

 south and middle of England. The smaller shrubs occu- 

 pying the commons and other exposed places are chiefly 

 d 6 



