marsh thistle (Cnicus pratensis), the sawwort (Serratula tinctoria), the dwarf willow (Salix ripens), the orchids Orchis ericetorum and Habenaria bifolia, the ferns Lomaria Spicant, Lastrea or Dryopteris spinulosa, dilatata, and at one time the royal fern (Osmunda regalis), the club moss (Lycopodium inundatum) and L. Selago, and the horsetail Equisetum sylvaticum. The bramble flora is also rich, and other glareal and ericetal plants, such as the cudweeds Gnaphalium sylvaticum and Filago minima, the red sandwort (Buda rubra), the cinquefoil (Potentilla argentea), the clovers Trifolium striatum and T. filiforme, the dog violet (Viola canina), the St. John's worts Hypericum humifusum and H. pulchrum, and the heath rush (juncus squarrosus), occur.
Gerrard's Cross Common has besides many of the heath plants already alluded to the camomile (Anthemis nobilis), the pennyroyal (Mentha Pulegium), and the chaffweed (Centunculus minimus).
The extensive common of Stoke Poges has a considerable number of very interesting species, among which may be mentioned the alder buckthorn (Rhamnus Frangula), the club moss (Lycopodium inundatum), the small scull-cap (Scutellaria minor), the all-seed (Millegrana Radiola), the pearlwort (Cerastium quaterncllum), masses of the dwarf furze (Ulex minor or nanus), the dwarf willow (Salix repens and its hybrid S. ambigua), the cudweed (Gnaphalium sylvaticum), etc.
The neighbourhood of Wycombe offers a very rich series of chalk plants which have already been referred to in the remarks on p. 38, but there are in addition plants such as the toothwort (Lathrea Squamaria), which grows at Hughenden, the vetch (Vicia gracilis), which formerly grew near Winter Hill, the white mullein (Verbascum Lychnitis) and the bloody crane'sbill (Geranium sanguineum), which grew on the banks of the railway with the woad (Isatis tinctoria) and are probably not native to Buckinghamshire. There also occur the periwinkle (Vinca minor), the rose Rosa systyla, the mint Mentha cardiaca, the sedge Carex paniculata, which is abundant in the marsh, the grass Bromus secalinus, extremely abundant in cornfields, the pretty Stachys annua of very local occurrence in arable soil, while the eyebright (Euphrasia Kerneri), the crane's-bill (Geranium rotundifolium) near West Wycombe, and the black mullein (Verbascum nigrum), are of local distribution.
Naphill Common has a special feature of interest in its being the home of the thrumwort (Damasonium Alisma), which is a diminishing species in Britain, and it also has some very fine juniper bushes (Juniperus communis); and a most luxuriant growth of the orpine (Sedum roseum) is in the neighbourhood.
I have already mentioned the characteristic species of the main valley of the Thames, but we may allude to some of the aquatics which it yields. They are not so numerous as formerly, as the more frequent traffic of steam launches of course exerts an inimical influence. There are however still recesses of the river where the fringed water-lily (Limnanthemum peltatum) abounds; the pondweeds Potamogeton prælongus, P. zosterfolius and P. interruptus, the water buttercup (Ranunculus fluitans), the water honewort (Ceratophyllum), the charad (Chara fragilis var. Hedwigii), the snowflake (Leucojum æstivum), the reed mace (Typha angustifolia),the American balsam (Impatiens fulva) now naturalized near Henley and bound to extend its area, the willows Salix purpurea, S. rubra and others, the water dropwort (Œnanthe fluviatilis) and in a backwater (Œ. Phellandrium, and the poisonous dropwort (Œ. crocata), the sweet flag (Acorus Calamus) are among the more interesting species. Near Henley there are the clary (Salvia Verbenaca) and the hound's-tongue (Cynoglossum officinale), the mistletoe (Viscum album) on limes, black poplar and even on thorns, the rampions (Campanula Rapunculus), growing in a very wild situation near Hambledon, the meadow sage (Salvia pratensis), the spurge (Euphorbia Esula) on the river bank in a wild condition, the rose Rosa systyla, the wild licorice (Astragalus glycyphyllus), the garlic (Allium vineale), and the bedstraw (Galium erectum). On a common near Marlow occur the clovers Trifolium subterraneum, T . striatum, and the vetch Vicia lathyroides; and in fields the grass Poa pratensis var. angustifolia, the honewort (Carum segetum), and the tansy (Tanacetum vulgare).
The wooded slopes of Clivedon are said to have yielded the golden saxifrage (Chrysosplenium alternifolium), but its occurrence has not been verified; the small teasel (Dipsacus pilosus) grows there, and the gravelly soil about Taplow has plenty of the lettuce Lactuca virosa, while the pretty grass Apera Spica-venti is common in the fields.
The meadows between Bray and Windsor have many interesting plants, but the special rarity has disappeared, namely Tordylium maximum, which at one time grew near Eton Wick. The water avens grows near Chalvey in the second locality known for it in Bucks, and also the rush Juncus obtusiftorus, the sedges Carex vesicaria, C. rostrata, C. Pseudo-cyperus, C. disticha and C. paniculata still grow there. The marsh stitchwort (Stellaria palustris), the water violet
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