SUMMARY 631 



neither the Pyrus nor the Lythrum have been observed by the author, 

 and the Elatine is very rare. 



Of the fifty species found in two counties only, four have been 

 recorded — Ballota ruderalis (which is now usually considered to be only 

 a variety of B. foeticla), Tordylmm, and Orchis Simla, but the two former 

 have not been seen by the author, and the latter is probably extinct ; 

 Thlasin perfoliatum appears to have been introduced. 



Of the fifty-eight species which are limited to a single county, we 

 have no true representative, since Rosa sepium {B. agrestis), which Mr. 

 Watson included in his list, has since been found in several counties. 



If we compare the flora of Oxfordshire with that of Berkshire, we 

 shall find that the two counties are more dissimilar than their 

 contiguity would have led one to expect. Oxfordshire possesses a few 

 interesting species not known to occur in Berkshire, and which are 

 chiefly found on the Oolite and Forest-marble geological formations 

 which do not extend into Berkshire. These species are Thlaspi 

 2Jerfoliatu7n, only found as a casual in Berkshire, Ctjnoglossiim montanimi, 

 Stachys gennatiica, Salvia jpratensis (perhaps only a casual in Berkshire), 

 Phegopteris calcarea (P. Robertiana), and Ophnjs aranifera (now possibly 

 extinct) ; Rumex Umosus, Viola persicaefolia, and Sonchus palustris, from the 

 once extensive fen district of Otmoor, but the two former not recently 

 observed ; Cephalanthera ensifolia, Phegopteris Dryopteris, and Antennaria 

 dioica, which have not been observed by me in Berkshire, but are found 

 on the Oxfordshire Chilterns ; Potamogeton decipiens, Rubus Powellii, 

 R.fusco-ater, Teucrium Chamaedrys, Aristolochia, Dianthus deltoides, and Festuca 

 heierophylla. The last four species, more or less naturalized in Oxford- 

 shire, are either not recorded or recorded only on unsafe authority for 

 Berkshire. A few local plants are more plentiful in Oxfordshire than 

 in Berkshire ; among them are Helleborusfoetidus, H. viridis, and Colchicum, 

 which are not only more frequent, but have a wider distribution in 

 Oxfordshire than in Berkshire. Pyrola minor, which is Avidely dis- 

 tributed in the woods of the Oxfordshire Chilterns, appears to be absent 

 from similar woods on the Berkshire side of the Thames, though it is 

 found in two localities on the Bagshot Sands in the latter county. 



The Berkshire flora, as will have been seen by the enumeration 

 already given, is larger than that of Oxfordshire, the extensive heaths 

 and bogs of the former county affording a home for many additional 

 species. To this category belong Ranunculus Lenormandi, Sagina subidata, 

 Drosera rotundifolia, D. longifoUa, Arnoseris, Ilypochoeris glabra, Gtntiana 

 Pneumonanthe, Myosotis repens, Illecebrum verticillatum, Myrica Gale, Xar- 

 thecium ossifragum, Scirpus caespitosa, Carex elongata, C. elata, C. laevigata, 

 Agrostis setacea, Osmunda, Phegopteris polypodioides, Pilularia glohulifera, and 

 Lycopodium inundatum, which are not known to occur in Oxfordshire. 



