GRASSLAND ASSOCIATIONS 263 



grassland are : Lolium perenne (perennial r ye-grass), 

 Anthoxanthum odoratum (sweet vernal-grass), Dactylis 

 glomerata (cock's-foot), Poa pratensis and P. trivialis 

 (smooth and rough meadow-grasses), Alopecurus pratensis 

 (fox-tail), Phleum pratense (Timothy-grass), Agrostis alba 

 (white bent-grass), Holcus lanatus (Yorkshire-fog), Cyno- 

 surus cristatus (crested dog's-tail), Festuca pratensis 

 (meadow-fescue), and F. ovina (sheep's-fescue). With 

 these grasses are mixed intentionally certain leguminous 

 plants e.g., clovers and on dry pastures these form a 

 large percentage of the seed sown. 



Weeds of Meadow-Land. The character of the weeds 

 in the meadow depends largely on the chemical and 

 physical nature of the soil. The plants are tall-growing 

 and, protected by the surrounding grasses, are mesophy tic , 

 with large thin leaves. Transpiration is often difficult, 

 owing to the humid atmosphere, and many of the plants 

 possess hydathodes (p. 27), by means of which the water 

 is got rid of in a liquid form. Saxifraga granulata ex- 

 hibits such a character in a pronounced degree ; the 

 water which is excreted contains a large amount of 

 calcium carbonate, which is left behind on the leaf as a 

 white chalky deposit when the water evaporates. They 

 are for this reason often called chalk-glands. As in the 

 natural pasture, competition is very keen, and all the 

 weeds are perennial or hemi-parasites e.g., Rhinanthus 

 and Bartsia. 



On damp, heavy soil the commonest weeds are : Rumex 

 Acetosa (sorrel), R. crispus (dock), Ranunculus repens 

 (creeping buttercup), R. bulbosus (bulbous buttercup). 

 Plantago lanceolata (ribwort-plantain), Garduus palustris 

 (marsh-thistle), Senecio vulgaris (groundsel), S. Jacobcea 

 (ragwort), Orchis mascula (early purple orchid), Traga- 

 pogon pratensis (goafs-beard), Prunella vulgaris (self-heal), 

 Lapsana communis (nipplewort), Lathyrus pratensis (yellow 

 meadow- vetchling), Cardamine pratensis (cuckoo-flower), 

 Geranium pratense (meadow crane's-bill), Spiraea Ulmaria 

 (meadow-sweet), Saxifraga granulata (meadow-saxifrage) ; 

 and the rare Crocus vernus, Fritillaria Meleagris (snake's - 

 head), and Colchicum autumnale (autumn-crocus, meadow- 

 saffron). Rhinanthus Crista-galli (yellow rattle) is found 

 in almost all meadows on clay land . 



In low-lying meadows near rivers the water-level is 



