Page:VCH Berkshire 1.djvu/88

 A HISTORY OF BERKSHIRE county, for the calcareous loving species, the broad-leaved helleborine (Cephalanthera palkns) and the yellow birds'-nest (Hypopitys Monotropa). The stone-crop (Sedum dasyphylluni) is abundant on many of the village walls built of this coral rag, and the navel-wort (Cotyledon Umbilicus) (once an abundant species on the walls of Oxford) also occurs and appears to be limited to this formation. The traveller's joy (Clematis Vitalbd), the hoary-headed thistle (Cnicus eriopborus], the grasses Avena pubescent, A. pratensis, Bromus erectus, Brachypodium pinnatum, the hairy violet (Viola birta), the salad burnet (Poterium Sanguisorba), the field chickweed (Cerastium arvense), the round-leaved cranesbill (Geranium rotundifolium), the hawk's beard (Picris Hieracioides), the gromwell (Litbo- spermum officinale] and the milk licorice (Astragalus glycyphyllus) are characteristic plants. Several very local species are found on it, including such well known calcareous loving xerophytes as these hygrophilous species are called, such as the pasque flower (Anemone Pulsatilla), the trefoil (Tri- folium scabrum), the flix-weed (Sisymbrium Sophia), the sandwort (Arenaria tenuifolia), the small-headed thistle (Carduus pycnocephalus var. tenuiflorus), the cotton thistle (Onopordon Acanthium), the lesser calamint (Calamintba parvifolia], the burnt orchid (Orchis ustulata), the rusty-back spleen wort (Ceterach officinarum) and the maiden- hair spleenwort (Asplenium Tricho- manes) . In some instances, especially on the eastern side of the Berkshire Corallian Beds, small streams have cut their way down through the lime- stone to the impervious Oxford Clay, and marshes and bogs of a very interesting character may then be seen, such as that at Cothill and those on the Boar's Hill range, where many original species may be found, including a pond weed (Potamogeton coloratus) not known to grow else- where in the county. The next belt is formed by the Kimeridge Clay, and consists of flat and unpicturesque country, with a stiff, cold, damp soil. It is from i to 3 miles broad. Many large fields, separated from each other by watery ditches, are found to occupy a considerable portion of the formation, which owing to its soil, and to its being almost entirely under cultivation, is very poor in botanical features. In addition to the plants mentioned as being plentiful on the Oxford Clay, we may allude to the prevalence of the two willow herbs Epilobium hirsutum and E. parmforum, and the water parsnip (Apium nodiflorum) in the watery ditches. The occurrence of drift gravels does something to relieve the monotony of its surface and flora, and at Bagley an extensive woodland tract already mentioned occurs which has several very interesting botanical features, including the ivy-leaved campanula (Cenncina [Wablenbergia] hederacea). The crimson grass-leaved vetchling (Lathyrus Nissolia) is found at the junction of the Kimeridge with the Corallian Beds, and the everlasting pea (L. syhestris] is locally common, as on the Boar's Hill range. One locality of special interest in the Kimeridge Clay area is a detached patch forming the meadows near Marcham. Here a spring rises from the junction of the Kimeridge with the Corallian Beds, and 42