BOTANY 



sulphate and carbonate of lime to allow plants such as the sundew or the 

 Lancashire asphodel to grow. There are interminable series of pastures 

 wearisome in their monotony, but in some of the meadows near Ayles- 

 bury the snake's-head (Fritillaria meleagris) is as common as it is in the 

 better-known locality of Oxford, and here from its being in such a 

 sequestered and unpopulated region, the indigenity of this interesting 

 species in the Upper Thames province is further strengthened. The 

 clay, which is often bituminous, with irregular bands of limestone nodules, 

 is sometimes of a dull leaden colour, as near Hartwell and Aylesbury, 

 where it is extensively worked for brick-making. Here and there are 

 tracts of woodland in which the oak is the prevailing tree, although 

 both species of elms attain large dimensions ; and the black poplar, 

 always slightly leaning to one side, and not I think always against the 

 wind, is a conspicuous feature in the low fields of the Vale, while the 

 course of the small, sluggish and turbid streams is marked by the 

 line of pollard willows, while the hop (Humulus Lupulus) and the large 

 bindweed (Calystegia septum) and the water stitch wort (Stellaria aquatica]^ 

 the willow herbs Epilobium hirsutum and E. paruiflorum, and the loose- 

 strife (Lythrum Salicaria) break by their display of colour the somewhat 

 dead monotony of the scene. 



THE PORTLAND BEDS are more largely represented in Buckingham- 

 shire than in Oxfordshire ; the main outcrop passes north-east from 

 Thame, forming a tract of drier soil, by Cuddington and Dinton to 

 Bierton and Aylesbury, where the rock is soft and sandy ; and there 

 are outlying masses at Brill, Muswell Hill, Ashendon, Whitchurch, 

 etc. Capping the Portland Beds are the PURBECK BEDS at Brill, which 

 exist as thin beds of drab-coloured close-grained limestones of fresh- 

 water origin, but they have not the characteristic calcareous flora to 

 the same degree as the Great Oolite or the Chalk. 



THE LOWER GREENSAND, which is formed of the lowest beds of 

 the Cretaceous formation, are of very irregular occurrence, but they 

 may be traced at intervals across the counties of Berks, Oxford and 

 Bucks, rising above the flatter and less elevated clay tracts by which they 

 are surrounded. We find that in the two first-named counties the well- 

 known hills of Faringdon, Boar's Hill and Shotover, consisting essen- 

 tially of the Greensand, are not only very striking and pleasing factors 

 in the effect they produce upon the outline of the country, but from 

 their being of a warm porous rock, overlying an impervious stratum, 

 the juncture of which is marked by a line of springs which offer a 

 congenial home for many interesting marsh plants, and from the water 

 often containing ferrugineous matter in solution, a true bog is formed ; 

 so that on this formation we obtain a more diversified flora than on 

 any of the previous formations yet considered. Nor does the character 

 deteriorate in Buckinghamshire ; indeed the tract of country on which 

 the Brickhills are situated, and whose rather striking escarpment faces 

 nearly north, clothed as it is with planted pine and larch, offers a 

 veritable oasis to the botanist, who may have been disheartened by 

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