BOTANY 



county, and although this necessitates some repetition of plant names, yet 

 the plan has the compensating advantage of showing how certain groups 

 of plants are to be found on the same soils. 



The geology of Buckinghamshire resembles very closely that of 

 Oxfordshire, except that the Liassic formations are exposed to a much 

 smaller extent in the former county, whereas the Reading beds and the 

 London Clay are but sparingly represented in Oxfordshire, but cover 

 considerable tracts of southern Buckinghamshire. The Lias Clay is 

 shown in the north of the county between Grafton Regis and Castle- 

 thorpe, owing to the Tove cutting its way down to it, but no very special 

 vegetation marks the occurrence, beyond the growth of the ordinary 

 pelophilous or clay-loving species. The Ouse, near Weston Underwood 

 and Stoke Goldington, has also cut down to the Lias in two or three 

 places, but again without exhibiting any plant of special interest. The 

 Northampton Sands, which cap so many of the eminences of north 

 Oxfordshire and west Northamptonshire, where from their porous nature 

 they give a warm soil and afford a home for many heath-loving species, 

 are practically unrepresented in our area, but the Great Oolite comes to 

 the surface in many places, and in fact extends in a more or less broken 

 band from Brackley and Buckingham in the west, by Potterspury to 

 Newport Pagnell and Cold Brayfield in the east, and then passes into 

 Bedfordshire. The contrast of the vegetation of that portion of country 

 where the Great Oolite comes to the surface with that district where an 

 impervious material, such as the Oxford Clay, forms the subsoil, is most 

 marked. Nor is it the vegetation alone which marks the difference. In 

 one case we find that the oolite has been quarried for building stone, so that 

 we see good stone houses and cottages, often with thatched roofs since straw 

 is more plentiful, which give a solid yet more picturesque character to the 

 scene than the brick and slated houses of the clay district, while the stone 

 walls of the villages, often mud-capped, afford a home for mosses and other 

 plants to a much greater extent than the better pointed brickwork. The 

 land too will be occupied more frequently by corn on the limestone and by 

 pasture on the clays, and thus the latter is usually a thinly populated area, 

 and such villages as do occur are often built upon some spot where a drift 

 deposit gives some amount of porosity to the soil. If we pass through 

 the county in the summer evenings, we may observe the white mist 

 clinging to the clay surfaces, while the pastures on the limestones will be 

 free. In comparing the more common plants we shall see on the Lime- 

 stone that the hedgerows often contain the buckthorn (Rbamnus cathar- 

 ticus), the spindle tree (Euonymus europceus), the wayfaring tree (Viburnum 

 Lantana), and are often adorned with the traveller's joy (Clematis 

 Vitalbd)^ the maple (Acer campestre}^ and occasionally the glabrous fruited 

 form, the cornel (Cornus europaus), and here and there the bramble 

 Rubus Radula, but the ubiquitous species is R. ulmifolius. Where clay 

 is present the spindle tree and cornel will be rare and the traveller's joy 

 absent, and the common brambles will be R. corylifolius and R. casius, 

 and there will be the bittersweet (Solanum Dulcamara) and the blackthorn 



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