GRASS-LAND WEEDS 177 



tolerated, and come into the weed category. The classification 

 of many other plants, as described above, depends upon 

 circumstances. 



Local conditions, often varying within small areas, do 

 much to determine the relative abundance of grass-land weeds. 

 The amount of water in the soil is a most potent factor in this 

 way, and its action is well seen on low-lying fields where the 

 water table approaches the surface of the soil rather nearly, 

 as happens in alluvial areas (cf. Berkeley district. Gloucester- 

 shire, and Sedgemoor, Somerset). These fields are often 

 thrown into ridge and furrow, the survivals of old arable 

 cultivation, and in the furrow where water-logging occurs 

 rushes and other moisture-loving plants abound. Up the 

 sides of the ridges the rushes gradually get fewer as the soil be- 

 comes slightly drier, and unless the field is abnormally low-lying 

 and damp the tops of the ridges are free from rushes. Coin- 

 cidently with the dying out of the rushes there is often an in- 

 coming of the tall buttercup (Ranunculus acris\ which likes a 

 considerable degree of moisture but cannot withstand absolute 

 waterlogging, so that the tops of the ridges, though bare of 

 rushes, are often colonised by masses of these buttercups. A 

 further sequence may be observed where the fields are slightly 

 higher and but little waterlogging occurs even in the furrows. 

 Then the rushes get less and eventually die out, the tall butter- 

 cup descends from the ridge into the furrow, and is replaced 

 more or less completely on the top of the ridge by the allied 

 bulbous buttercup (R. bulbosus\ which is even more impatient 

 of an excess of water. The above illustrates what is often seen 

 in the West Country, but with possible variation in the plants 

 concerned it gives a good picture of what may be expected to 

 occur in any locality when excess of water is present. Drain- 

 ing gullies and depressions in grass fields are often colonised 

 by various species of docks. The broad-leaved dock (Rumex 

 obtusifolius} tends to congregate in places where the water 

 spreads out to flood the fields, while the sharp dock (R. con- 

 glomerates] and the blood-red dock (. sanguineus) frequent 

 the gullies and shady places and the edges of fields. 



Where the water supply is particularly abundant, as on 

 peaty soils, the herbage takes on quite a different character 

 from that found in drier situations as the typical grass-land 

 plants are less plentiful, their place being taken by a number 

 of miscellaneous plants usually regarded as weeds of low 

 nutritive value, such as ragged robin, meadowsweet, cotton 



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