BOTANY 



The flora of east Gloucestershire is but imperfectly known, so that 

 Berkshire possesses a very large number of species which are not recorded 

 for it. Several of the Berkshire species are not likely to occur in 

 Gloucestershire, nor are we at all likely to have as native plants many of 

 the above species. 



The geological map of Berkshire shows that the outcrop of the 



several formations appears as a series of approximately parallel strips 



crossing the county from west to east, and the dip of the beds is to the 



south ; so that in travelling from north to south we pass continually on 



to more recent beds. For botanical purposes subdivisions of the county 



are essential, and following the practice adopted in the floras of the 



bordering counties, including my own Flora of Berkshire, these divisions 



are based, not upon soils or geological formations, but upon river drainage, 



as by many authorities the latter leads to the most valuable scientific 



results. Much however is said in favour of choosing divisions based 



upon the geological formations, but the extent to which these are obscured 



by surface deposits negatives to a great extent its value, the influence 



of the surface soil being infinitely more powerful than the bed rock far 



below. We shall find however that the divisions based upon the river 



drainage in such a small area as the one we are treating of is by no 



means perfectly satisfactory for several reasons, among which may be 



named the difficulty in suggesting boundaries when the gradient is so 



small as that which occurs in some places, while the fact that some of 



our streams run transversely to the geological formations, and not unfre- 



quently cut through several beds of extremely different character, also 



give results which may perplex the student of phyto-geography. In 



passing we may mention that the oldest and most northern geological 



formation represented in the county is that of the Oxford Clay, which, 



as will be seen from the map, occurs on a narrow strip of low-lying 



land, chiefly pasture, a mile or two across, which borders the southern 



bank of the Thames from Lechlade to Botley, and it also stretches in 



the west from Lechlade to Coleshill and on the east as far south as 



to Iffley. It offers no exceptional plant vegetation, but the graceful 



sedge (Carex pendula) is very abundant on it in Wytham Woods, the 



Cyperus grass (Scirpus sylvaticus) is plentiful in one locality, and the 



horsetail (Equisetum maximum) is also frequent at its junction with the 



coralline oolite in several localities. Plants which are exceptionally 



common on it are a groundsel (Senecio erucifolius] , the teasel (Dipsacus 



syfoesfris), the hard rush (Juncus glaucus) the ox tongue (Picris Echioides), 



the knapweed (Centaurea nigrd) and the fleabane (Pulicana dysenterica), 



but these also reappear on the other impervious formations. 



Next in order are the Corallian Beds, which afford a valuable soil, 

 sandy or rubbly, but always porous and warm according as sand or lime- 

 stone forms the bed rock. On the south these beds can be traced trom 

 Shrivenham and Faringdon eastwards in a belt about 3 miles wide as far 

 as Abingdon. At Wytham they form a picturesque outlier which rises 

 to a height of 538 feet, and give a home, the most northerly in the 

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