with the crimson blossoms of the hard-head (Centaurea nigra) as the variety decipiens, and there is abundance of the purple flowered autumnal felwort (Gentiana Amarella), and in a few places the much larger blossomed Gentiana germanica. Three or four species of the eye-bright Eupbrasia occur, including nemorosa, curta, Kerneri and gracilis, but some of these grow where there is a thin coating of loamy soil or possibly brick-earth.
In the deep combe above the Kembles and Ellesborough there are great bushes of the box (Buxus sempervirens), and it may be native in the county here and on the downs above Edlesborough. At Ellesborough it affords shelter for a great number of rabbits, and about their warrens the henbane (Hyoscyamus niger) is abundant, and growing upon the earth thrown out by them one of the earliest plants to appear is the sandwort (Arenaria leptoclados). The tower cress (Arabis hirsuta) is found plentifully in a few situations, but is most abundant in shade, which is rather unusual for this species. Nor do the arable fields lack their complement of interesting plants, and the white mustard and candy-tuft have been already mentioned, but there are also the fumitories Fumaria densiflora, F. Vaillantii and F. parviflora, the toadflax (Linaria viscida), the sainfoin (Onobrycbis "viciteformis), but the special treasure is a very local species which has its extreme western range in the county, namely the great pig-nut (Carum Bulbocastanum), which also occurs in Cambridgeshire and Herts, but does not appear to extend west of Ivinghoe. The large tuberous root is greedily eaten by pigs. About Halton and Tring there is the poisonous deadly nightshade (Atropa Belladonna), the spurge laurel (Daphne Laureoa), the very local bedstraws Galium sylestre and G. erectum, the meadow clary (Safoia pratensis), and the field mouse-ear (Cerastium arvense); Vicia slvatica, Polygonatum multiflorum and Pyrola minor.
The Chalk is occasionally covered with leaf-mould and with loam, or brick-earth, and when the calcareous character of the soil is more or less masked a corresponding change in the flora takes place; patches of the ling (Calluna Erica), of the louse-wort (Pedicularis sylvatica) and other ericetal plants occur, but as these are not normal constituents of a cretaceous flora they will be referred to subsequently. There are three large dips in the Chiltern escarpment: one near Princes Risborough, another near Wendover, and a third which lies between Tring and Aldbury. The neighbouring hills such as Beacon Hill near Wendover and those above Ivinghoe and Halton give very beautiful and extensive views over the vale to the distant hills of Northants and Wilts. The chalk rock of the Lower Chalk is also to be seen inland at Chesham, High Wycombe, as well as in several places overlooking the Thames between Henley and Marlow.
The Upper Chalk with Flints is about 300 feet thick, and forms the eastern slope of the Chiltern Hills. This chalk is largely burned for lime. Although there is a considerable portion of the chalk area where the Upper Chalk forms the subsoil and gives a home for calcareous loving
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