30 Plant-life of the Oxford District 



The number of locally indigenous trees of high forest, as opposed to 

 smaller forms of underwood, maintaining their position by natural reproduc- 

 tion, is extremely limited ; possibly only half a dozen, as : Oak, Ash, Wych 

 Elm, Alder, Birch, Hornbeam, and not all of these are seen locally freely 

 germinating from seed (Oak, Ash, Birch). Other large and familiar tree- 

 forms are of comparatively recent introduction, and imperfectly naturalized ; 

 that is to say, always planted. Some of these may produce quantities of 

 good seed (Sycamore, Horse-Chestnut, Walnut), others do not seed at all, 

 or only rarely (Common Elm, Plane, Lombardy Poplar, Black Italian 

 Poplar, Grey Poplar, many Willows). The same applies to the case of 

 Conifers : Pinus sylvestris was indigenous, but is now only grown by plant- 

 ing, as also is Taxus. Spruce (Picea excelsa) and Larch (Larix eiiropaea] of 

 Central Europe, may be largely planted, but do not always mature seed. 

 Cedars rarely do so. These again are Northern Conifers still attempting to 

 mature seed in one season, a problem solved more successfully by Pinus t 

 which goes farthest north, by taking two. In dealing with introduced forms, 

 it must be noted that it is not so much a question of the successful growth 

 of the individual, which determines its success as an ecological constituent of 

 the flora, as its capacity for producing fertile seed, and ability to grow from 

 such seed in competition with other plants. Failure in seed-maturation, or 

 restriction of fertile seeds below the amount required to counter-balance the 

 normal wastage of the reproductive mechanism, is fatal to the race, and is 

 the direct effect of a shortened working season with enfeebled light-supply, 

 or lack of adjustment of the inherited periodicity of the plant to that of the 

 climate. 



Confirmation of such deductions as to the original forest-flora may be 

 seen in the phenomena of regression of cultivated land and pastures, when 

 left derelict, to their original condition. Thus thorn-scrub ( c thicket ') gives 

 place ultimately to woodland trees, as Ash and Oak in good ground, and in 

 the water-meadows Salix (sp.), Alnus, Fraxinus, and Populus grow freely 

 in ditches and hedge-rows. In a short period the entire district would 

 revert to general woodland, and there can be no doubt that the original 

 state of the country was that of the general forest of the central plain of 

 England, much as first described in literature by Caesar, and left largely 

 uncleared to the coming of the English, as locally a broad tract of swamp- 

 forest, penetrated by water-courses, above which low wooded-hills emerged ; 

 the lower ground affording a tangled mass of vegetation, only swept clear 

 by winter-floods, to which the land would soon revert if left vacant of human 

 occupation. 



By Neolithic man with a few domesticated animals, hill-clearings were 

 made by fire, and valley-clearings similarly afforded pasture for sheep and 

 cattle. The introduction of cattle implies the simultaneous introduction of 

 many weeds and grasses of pasture-land, now passing as indigenous, but not 

 found in woodland-clearings. But casual grazing will not keep land from 

 regressing to scrub: constant firing was undoubtedly the oldest method of 

 keeping the woodland in check, as it is still employed to keep down Gorse 

 and Bracken, regressive thorn-scrub and brambles. Only in later times does 

 the use of the scythe effectively produce the permanent pasture of grass-lands 

 by annual mowings. 



The first English settlers cleared the whole of the level alluvial tract, more 

 or less submerged in winter-months, as grazing-land for their cattle fed in 

 winter by the hay-crop, to the beginning of the rising ground. The latter 

 they tilled for their own food-supply as corn; and cultivation spread up the 

 low slopes of the hills, leaving the tops still covered with wooded caps, and 

 the valley-slopes dotted with small holdings. The complete clearing of the 

 alluvial flats as water-meadows, was the essential factor in the colonization of 



