78 THE STORY OF PLANT LIFE 



The ground flora includes some plants of the damp 

 oakwood (where it is drier), such as Wood Violet, 

 etc., and Beautiful St. John's Wort, Perforate St. 

 John's Wort, Wood Sorrel, Tormentil, Barren Straw- 

 berry, Rosebay, Heath Bedstraw, Golden Rod, Hawk- 

 weeds, Foxglove, Woodsage, Sheep's Sorrel, Wood- 

 rush, Yorkshire Fog, Bent Grass, Bracken, Hard 

 Fern, etc. (see Fig. 14). 



The grass heath on dry soils is characterised by such 

 plants as Vernal Grass, Wood Violet, Milkwort, 

 Moenchia, Sandwort, Pearlwort, Grassy Stitchwort, 

 Purging Flax, Stork's Bill, Gorse, Broom, Lesser 

 Trefoil, Hare's Foot Trefoil, Tormentil, Parsley 

 Piert, Pignut, Milfoil, Mouse Ear Hawkweed, Spear 

 Thistle, Carline Thistle, Harebell, Ling, Heath, 

 Centaury, Dwarf Forget-me-not, Wall Speedwell, 

 Eyebright, Wild Thyme, Knawel, Sheep's Sorrel, 

 Early Sedge, Bent Grasses, Silvery Hairy Grass, 

 Heath Hair Grass, Sieglingia, Bracken, etc. (see 



Fig. 15). 



Heaths are developed on sandy or gravelly soils, 

 usually dry, with dry peat, or a wetter soil and pure 

 acid humus. Here mosses and lichens often form a 

 thick ground layer. Heaths are interspersed within 

 the dry oakwood, with Bilberry, Heath Hair Grass, 

 and Ling. When more nearly related to the latter 

 the oak-birch heath association forms open areas 

 with oak, birch, and some oakwood ground flora 

 types as Bluebell, Wood Anemone. Amongst the 

 trees are also Beech, Pine, Holly; and the shrubs 



