368 ECOLOGY 



abundant, especially at rather lower levels. Associated with 

 these in the drier parts are many heath-plants, e. g. Ling, 

 Cross-leaved Heath (Erica Tetralix), and Bilberry. In the 

 wetter parts of these grass moors the ground is occupied by 

 huge tussocks of the Purple Moor-grass (Molinia caerulea). 

 In spring its pale yellow-green leaves, especially those 

 following the burning of the moor, are very striking. 



Calcareous grass-land. Very different are the calcareous 

 grass-lands of the hill-slopes of the mountain limestone and 

 the great sheep-grazing grounds of England, the Chalk 

 Downs. The Mat-grass, Waved Hair-grass, and Purple 

 Moor-grass are absent, and in place of their tussocks we 

 have a much shorter grassy turf dominated by the Sheep's 

 Fescue-grass (Festuca ovina), and with it the Lesser Meadow 

 Rue (Thalictrum minus), Lady's Fingers (Anthyllis Vulne- 

 raria), Horseshoe Vetch (Hippocrepis comosa), the Lesser 

 Burnet (Poterium Sanguisorba), the Rock Rose (Helian- 

 themum Chamaecistus) , the Lesser Scabious (Scabiosa Colum- 

 baria), and the Hoary Plantain (Plantago media), all of which 

 are absent from siliceous grass-land. 



Neutral grass -land. Where much leaching has occurred, 

 on calcareous slopes, heath-plants are found alongside 

 typical calcareous species. They are small at first and 

 hidden by the grass ; but in places they become dominant 

 and form a limestone heath. When grass-land is heavily 

 grazed and manured, the number of species is, as a rule, 

 reduced, and the typical plants of the two previous types 

 of grass-land are rare or absent. This is called neutral 

 grass-land and is dominated by such species as the Rye- 

 grass (Lolium perenne), Vernal -grass (Anthoxanthum odora- 

 tum), Cock's Foot -grass (Dactylis glomerata), Yorkshire Fog 

 (Holcus lanatus). Many of these species, however, may 

 occur within a limited area, and much may be learnt from 

 a careful study of an old pasture or a meadow. 



Meadows. Because of their higher cultivation, meadows 



