BOTANY THE RIVER DRAINAGE OF BERKSHIRE as used for dividing the county into botanical districts must be next considered. Berkshire is wholly in the Thames basin, the area of which is about 5,162 square miles, or over 3,300,000 statute acres. For no miles of its course the Thames forms a boundary for Berkshire. At the point of its touching Berkshire near Lechlade it receives a small stream, the Cole, which rises from the chalk hills of north Wiltshire near Idstone. It is this small portion of our county, as well as the long strip, chiefly of Oxford clay, and the corallian oolite ridge which stretches from Oxford to Faringdon, which is com- prised in our first division, namely i. THE Isis OR UPPER THAMES, which corresponds to the district ' Thames 3 ' of Preston's Wiltshire Flora, and to the district ' 5. Isis or Upper Thames ' in my Oxfordshire Flora. It would perhaps have been well to subdivide this into two parts, that drained by the Cole, and the second into that portion drained by the main stream from Faringdon to Oxford ; the Cole itself contains a country with very varied geological character, since the stream drains the upper and lower chalk, the upper and lower greensand, the gault, the Kimeridge clay, the corallian oolite and the Oxford clay, while the portion drained by the main stream only consists of the two latter, and it is consequently much less diversified in scenery and much less rich in vegetation than the former. The northern boundary of the district is the Thames, the western boundary is the Cole and the county of Wilts, and the southern boundary is practically that of the turnpike road between Oxford and Faringdon. From this highway very extensive and pleasing prospects can be obtained, and many interesting species occur even by the roadside. In this district the beautiful estate of Wytham is con- tained, and this yields several varieties. It is the only locality known with us for the rose Rosa agrestis, and it is the most northern locality for the orchid Cephalanthera pollens. In the woods still grow the beautiful wood vetch (Ficia sylvatica), and the deadly nightshade (Atropa Belladonna), the yellow star of Bethlehem (Gagea fascicularis), the henbane (Hyoscyamus niger), the hound's tongue (Cynoglossum ojficinale), the gromwell (Lithospermum officinale), the herb Paris (Paris quadrifolia), the elecampane (Inula Helenium), the spurge laurel (Daphne Laureola), the wild everlasting pea (Lathyrus sylvestris), the large burnet saxifrage (Pimpinella major), the small buttercup (Ranunculus parviflorus], Samolus Valerandi, the bog pimpernel (Anagallis tenella), the spindle tree (Euonymus europaus) and birds' nest (Hypopitys) occur, as well as a most profuse growth of Carex pendula. Between Wytham and Faringdon the district of the upper Thames is well cultivated, heathland and true bogland being almost entirely absent, so that Drosera, Narthecium, Erica, Calluna, Juncus squarrosus, Plantago Coronopus, Anthemis nobilis and Salix repens, so common in the south of the county, are very rare or wanting, nor are the natural woods very extensive. On the corallian oolite the great thistle (Cnicus eriophorus) is found, and also the zigzag clover (Trifolium medium), the mullein (ferbascum nigrum), and the calaminth (Calamintha montana), while the grasses Bromus erectus, Brachypodium pinnatum and Avena pubescens are common, and Keeleria cristata local. The Thames meadows have a rich riparian vegetation, which includes the great spearwort (Ranunculus Lingua), the bitter cress (Cardamine amara), the bogbean (Menyanlhes trifoliata), the stitchwort (Stellaria palustris), the louse wort (Pedi- cularis palustris), the sulphur wort (CEnanthe silaifolia), the bistort (Polygonum Bistorta), and the elegant water parsnip (Sium latifolium). It has one feature of special interest in the occurrence in some plenty over a limited area of the water germander (Teucrium Scordium), a very rare and local and decreasing species in Britain, which was first made known as a British species from the neighbourhood of Oxford in 1552, but which appears to be quite extinct on the Oxfordshire side of the Thames. In some of the sluggish waters grow the bladderwort (Utricularia vulgaris), the water primrose (Hottonia palustris), and the frog bit (Hydrocharis Morsus-ranie. A characteristic grass is Bromus commutatus. In the main streams there are quantities of pondweed, but they chiefly consist of common species, Potamogeton interrupts being especially a noticeable feature, with the buttercup (Ranunculus fluitans). Here and there the beautiful fringed water lily (Limnanthemum peltatum) occurs, and both the common yellow and white lilies abound. The ornamental waters at Buscot have both species of reed mace (Typha), and the mare's tail (Hippuris), and Lotus tenuis, and the leopard's bane (Doronicum Pardalianches) occur in the vicinity. In Buckland Park the bear's foot (Helleborus viridis) and the box tree 51
