BOTANY 



its water is loaded with a sufficient percentage of chloride of sodium to 

 exert a considerable influence upon the surrounding vegetation, so that 

 several maritime or sub-maritime plants occur in this inland situation. 

 They are the sea sandwort (Buda marina), the sea club-rush (Scirpus mari- 

 timus), a rush (Juncus Gerardi], a sedge (Carex distant], \he celery (Apium 

 graveolens), the water dropwort ((Enanthe Lacbenalii], and a horned pond- 

 weed (Xannichellia maritima], the X.pedunculata, Reichb., of my Berkshire 

 Flora. In addition to these there are forms of Atriplex deltoidea and of 

 Agrostis alba, which resemble the marine forms of these plants. 



THE PORTLAND BEDS exist only as a small outlier on which the 

 village of Bourton is built, and the formation does not exhibit any 

 special plants. 



THE LOWER GREENSAND occupies a much less continuous belt than 

 the formations already alluded to, as in places it is overlapped by the 

 gault. The outlier of Boar's Hill, where it reaches its highest point in the 

 county of 535 feet on Pickett's Heath, Faringdon Clumps and Badbury 

 Hill in the west of the county are capped by the formation, and there 

 are some picturesque cliffs of it at Clifton Hampden. These detached 

 areas of the Lower Greensand form a light sandy soil, and offer a home 

 for many interesting and local species. The bramble flora especially is 

 as rich as it is poor on the Oxford Clay and Gault. The crimson poppy 

 (Papaver hybnduni), the pink (Tunica prolifera), the English catchfly (Silene 

 anglicd), the sheep's scabious (Jasione montand), the heaths Galluna and 

 Erica cinerea, the climbing bindweed (Polygonum dumetorum) and many 

 other species are found on it. 



The Lower Greensand contrasts very markedly in the character of 

 the scenery from that of the Oxford Clay and Gault, which is further 

 accentuated by the fact that the flora itself is so very different in 

 appearance. 



THE GAULT forms another zonal band, i to 3 miles in width, across 

 the county, and consists of a blue clay which is usually calcareous and 

 often micaceous. It forms a stiff, heavy and rather cold soil, which 

 were it not for a few deposits of drift would be a singularly undiversified 

 country, either as regards its scenery or its vegetation. The sparsity of 

 woodland is an especially noticeable feature, and accounts for the absence 

 of many sylvan species from the district. The ragwort (Senecio tenuiflorus) 

 is a conspicuous plant, and the willow herb (Epilobium tetragonunf), and a 

 hybrid of this with E. parviflorum occur. The marshy meadows afford 

 the orchid (Orchis incarnata) and the bogbean (Menyanthes trifoliate?) . 



THE UPPER GREENSAND occupies a belt which narrows, from 5 

 or 6 miles at Wittenham, till it almost thins out at Woolstone, and 

 forms a steep terraced escarpment to the south of the Gault plain. The 

 upper part is calcareous, and also contains occasionally phosphatic matter ; 

 therefore the soil is very fertile, which is further increased by the supply 

 of marly debris which every shower washes down from the chalk 

 escarpment and spreads over its surface. The flora is consequently 

 much more varied than that of the Gault. About twenty miles south 



43 



