A HISTORY OF BUCKINGHAMSHIRE 



species, yet there is an even larger portion coloured as chalk on the 

 geological map, which is really covered with a reddish earth to which 

 the name of ' brick-earth ' is given, and when this is present it so modifies 

 the vegetation that a very dissimilar flora will be found from that where 

 the chalk itself forms the surface soil. The chief tree in the woods is of 

 course the beech, with hornbeam ; and occasionally the cherry ; and 

 the ash is not unfrequent in open situations, while in some of the more 

 clayey and sheltered places the oak is found. The plant of special interest 

 is the local coral-root (Cardamine bulbifera), the Dentaria bulbifera 

 of Linnams, so named from the curious bulbils present in the axils of the 

 leaves. These bulbils drop ofF and form another plant, thus enabling it 

 to perpetuate itself without seeding, which as it grows in rather dense 

 shade is not of frequent occurrence. The plant prefers to grow where 

 there are plenty of loose flints and leaf-mould in hilly woods, and although 

 extending into Herts and Berks has not yet been found in the woods 

 of the Oxfordshire Chilterns. The helleborines Epipactis latifolia and 

 E. violacea are found as well as occasionally the herb Paris (Paris quadri- 

 fo/ia), the gromwell (Lithospermum officinale), the large woodrush (Luzula 

 or Juncoides syhatica], the lady's mantle (Alchemilla vu/garis), the beautiful 

 wood vetch (Vicia syfoatica), the very rare and interesting shrub Daphne 

 Mezereum, as well as the spurge laurel (D. Laureola), the mountain speed- 

 well (Veronica montana), the sedges Carex pallescens and C. strigosa, the 

 grasses Milium effusum and Me/tea uniflora, the toothwort (Lathrea Squa- 

 maria], the willow herb (Epilobium angustifolium), besides Pimpinella major. 

 The Chalk in this southern area, although so frequently obscured 

 by the deposits alluded to, is at intervals the surface rock, especially on 

 the sides of the dry valleys or deep road-cutting. When this is the case 

 the vegetation at once changes in character, and in the calcareous woods 

 we have the yew (Taxus baccata], the juniper (Juniperus communis) , the 

 hornbeam (Carpinus Betu/us), all certainly native ; the wood barley (Elytnus 

 europceus), which can also grow where there is some covering to the chalk ; 

 the wood rush (Juncoides [Luzula] Forsferi), and much more locally the 

 Solomon's seal (Polygonatum multtfloruni) , so much rarer here than in the 

 woods on the Berkshire chalk hills, and this again prefers some coating 

 either of leaf-mould or even brick-earth ; the rare military orchid (Orchis 

 militaris], one of the chief botanical treasures of the county, but now much 

 less frequently occurring than was formerly the case, and chiefly on the 

 borders of woods ; the mountain St. John's wort (Hypericum montanum), 

 the tutsan (H. Androscemuni), the two hellebores Helleborus viridis and 

 H.fcetidus, but both locally ; and with a still more restricted distribu- 

 tion the oak fern (Pbegopteris Dryopteris] and the limestone polypody 

 (P. calcarea) ; a hawkweed (Hieracium murorum var. pellucidum) , and more 

 commonly the ploughman's spikenard (Inula Conyza). The stinking 

 gladdon (Iris foeti dissima), the butcher's broom (Ruscus acu/eatus), the 

 wild licorice vetch (Astragalus glycyphyllos], the blue toadflax (Linaria 

 repens) are chiefly found on the chalk hills overlooking the river. On the 

 grass-covered downs the musk orchid (Herminium Monorchis) and the large 



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