270 BRITISH PLANTS 



deep marly soils. The birch is also common in the 

 lowlands, but in the uplands it beats all trees, and ulti- 

 mately entirely supplants the oak, ash, and beech at the 

 higher altitudes of tree-growth on all kinds of soils. From 

 the great admixture of other trees competing with the 

 oak for dominance, these woods are often called mixed 

 deciduous woods. The hazel is the most common shrub 

 of the undergrowth, and in woods periodically cut oak- 

 hazel coppices are formed. 



Vegetation of the Damp Oak-Wood — l. Trees. — Quercus 

 Robur ( = pedunculata, with stalked acorns) is the dominant 

 tree on deep soils, Q. sessiliflora (with sessile acorns) on 

 shallow soils ; ash, birch, beech, hornbeam ; and of trees 

 commonly planted — sweet chestnut, sycamore, poplars, 

 lime, and elm. 



2. Shrubs. — -Hazel (most abundant), maple, sloe, haw- 

 thorn, elder, bramble, wild rose, honeysuckle, sallow- 

 willow (Salix Ca'prea), holly, dogwood, and -guelder-rose. 



3. Herbaceous Undergrowth. — Anemone nemorosa, Pri- 

 mula vulgaris, Scilla nutans (on loose soils), Mercurialis 

 perennis, Ranunculus Ficaria, Euphorbia amygdaloides 

 (wood -spurge), Stellaria Holostea (greater stitchwort), 

 Oxalis Acetosella, Viola sylvatica, Sanicula europcea, 

 Geranium Robertianum, Epilobium montanum, Lamium 

 Galeobdolon, Lysimachia nemorum (yellow pimpernel), 

 Nepeta Glechoma, Lychnis dioica, Ajuga reptans, Prunella 

 vulgaris ; woodland - grasses : Milium effusum, Bromus 

 giganteu^, Brachypodium sylvaticum, Melica uniflora, etc. ; 

 ferns : Aspidium Filix-mas, Athyrium Filix-foemina, and 

 in light soils Pteris aquilina. 



(b) Upland Type. — A dry oak-wood is found on dry, 

 non-calcareous soils at an altitude of 500 to 1,000 feet. 

 The wood is more open than on the lowlands, and this 

 favours a thick shrubby undergrowth and a luxuriant 

 ground-vegetation. But this diminishes as the soil 

 becomes drier and the altitude increases. The soil is 

 deficient in humus, and the undergrowth includes a small 

 proportion of heath-plants (ling, gorse, bracken, etc.) 

 exhibiting xerophytio characters. As the altitude in- 

 creases birches gradually succeed in dominating the oak, 

 and at about 1,000 feet the oaks disappear altogether, 

 while the birches continue up to the limit of tree-growth 

 (1,500 feet in England). The ash is absent, and likewise 



