Waste Heaps and Derelict Ground 89 



into active competition for water and free room to develop. As the perennat- 

 ing stocks accumulate dead leaves and dust, worms become active, the soil 

 grows, and in a few years the debris may be completely covered with a weed- 

 vegetation which is in turn dominated by grasses, and in the course of time 

 will give turf of grass-land ultimately regressive to thorn-scrub (cf. Rubbish 

 heaps of Headington Quarry). 



The stages in such a progression afford an interesting study from the 

 point of view of the time taken, and the use of such vegetation in the often 

 insistent problem of covering up the inevitable waste of civilization. 



As a special case, more removed from the immediate vicinity of human 

 occupation, may be included the Hayrick Site. In all pastures cut for hay, 

 the usual practice is to have the rick in the corner of the field most avail- 

 able for transport, to save labour at harvesting. Hence in most hay-fields 

 there is a space marked off as a site for one or more ricks, as the crop is cut 

 in successive seasons, and is not necessarily sold or utilized. The fate of 

 such areas affords a few points of interest. Originally taken as the most 

 convenient, and in low-lying meadows the highest spot for the sake of drain- 

 age, and often built on a brushwood bottom, the rick begins by wholly 

 killing off the plants beneath it ; and when it is removed, presents not only 

 a denuded area, but one well-enriched with accumulated debris and the 

 washings of the waste. As soon as the site is exposed for new colonization, 

 it is covered by a particularly luxuriant growth of weeds ; and such sites 

 become the best grounds to search for local intrusives and samples of the 

 weeds in the fields around. 



Rank growths of Nettles, Docks, Chenopods, Atriplex, Polygonum, Seneczo, 

 Taraxacum, Poppies, Plantains, Raphanus, Sinapis, Arctitim, and Carduus, 

 spp., are especially characteristic, with equally luxuriant grasses as Dactylis, 

 Arrhenatherum, Alopecurus, Agropyrum, Phleum, etc., all doing so much better 

 than in the open pasture, that they attract attention, and one visits such 

 localities to find species making good specimens. These sites are often 

 strikingly conspicuous in the summer, affording a blaze of scarlet Poppies, 

 yellow Charlock, white Radish, and mauve Carduus arvensis^ in close association 

 with adjacent arable crops which may be fairly clean, and for which they provide 

 a continuation of the weed-flora. These give place to biennials, flowering the 

 second season, and perennials. Keck, Thistles, Docks, Heracleum, long hold 

 their own, though the grasses become dominant in the long run. Mowing will 

 put an end to the larger growths more rapidly ; and if seedlings of thorns are 

 kept down, the site returns to normal pasture in the course of time ; though it 

 may be long marked as a slightly raised area on which the grass grows stronger 

 and of a deeper green. 



Corresponding stations based on manure-heaps of arable fields, or general field- 

 waste, may present similar phenomena in an exaggerated form. But such 

 plants of cultivation and aliens do not invade the pastures. 



