CHAP. LXXXIX MEADOW 323 



of true grasses, including Poa, Alopecurus, and the like, and of tall 

 perennial herbs. In all countries in which atmospheric precipitations and 

 moisture are equably distributed throughout the year, and in which man 

 has practised cultivation for so long as to make his influence felt, there are 

 artificial communities of grasses and herbs, to wit, meadows and pastures, 

 that essentially owe their origin and composition to man. Many of these 

 communities in cultivated countries grow on soil that was formerly clothed 

 with forest, which has been destroyed by human agency ; they 

 are thus ' secondary ' productions. If we were to leave these to them- 

 selves, in time, they would certainly give way to forest. By manuring, 

 cropping, and grazing, meadows have been more or less modified, especially 

 as regards their constituent species. There are, on the contrary, meadows 

 that are not the result of cultivation ; such, for instance, occur on high 

 mountains, or near streams, where floods or ice exclude tree-growth. 



In this and the next chapter we shall deal mainly with North-European 

 meadow and pasture, which are two types of communities associated 

 respectively with moderately moist and moderately dry soil. Natural 

 meadow is more frequent than natural pasture, which is rare. 



As providing types of meadow the lowlands of northern Europe may 



Meadow stands as a link between mesophytic and hydrophytic com- 

 munities ; some types of it are more closely allied with the latter, others 

 distinctly belong to the former. The soil has a definite degree of humidity, 

 which is 60 to 80 per cent, of full saturation. Its ground- water lies deeper 

 and varies more in level than in swamp, and also flows more freely, so 

 that the soil is periodically aerated. The soil is often rich deep humus, 

 but may be sandy, particularly in the case of new meadows. 



Meadow is a community of tall, long-stemmed, perennial herbs, and 

 especially of true grasses. The covering of vegetation is closely continuous 

 and compact, has a dense tangle of roots and rhizomes, and its plants are 

 usually tall, being a foot or more in height, so that the soil is invisible. 

 The vegetation owes its density in no slight degree to mowing and grazing. 

 Mowing very materially affects the conditions of life of meadow, in that 

 it prevents the maturation of seeds, promotes branching, and modifies 

 the composition of the flora. The same effect as is produced by mowing 

 is naturally brought about by regular summer-floods in the neighbour- 

 hood of many rivers. In the middle of the vegetative season all the plants 

 are thus robbed of their vegetative epigeous organs. 



The vegetation in summer is of a fresh-green tint, and, when estimated 

 according to individuals, and often according to species, is mainly com- 

 posed of Gramineae that have flat, fresh -green leaves which do not roll 

 up in dry weather. The genera of grasses present include Aira, Avena, 

 Dactylis, Festuca, Poa, Holcus, Anthoxanthum, Alopecurus, Phleum, 

 Briza, Agrostis, and others. Often from twenty to thirty species of these 

 are uniformly distributed throughout the same meadow. In addition to 

 grasses the vegetation is formed by many monocotylous and dicotylous 

 perennial herbs, belonging to the Ranunculaceae, Papilionaceae, Com- 

 positae, and so forth. But trees and shrubs are almost excluded (the 

 latter may be represented by Salixrepens), as are annual species, excepting 

 on mole-heaps, where, for instance, Saxifraga tridactylites occurs. Meadow 

 is distinguished by its wealth of blossom and consequent abundance of 



Y2 



