Page:VCH Cornwall 1.djvu/101

 BOTANY A BRIEF glance at a map of Cornwall would prepare the average field botanist for a rich harvest. Favoured geographically, in- asmuch as they come within range of the genial operations of the Gulf Stream ; including a coast line which may be taken approximately as 250 miles ; furnished with a chain of bold hills forming a sort of backbone to the county ; and including among other advantages densely wooded and well watered valleys opening to the sea on both the north and the south coast, a good deal of land peculiarly favour- able to paludal and ericetal plants, and long stretches of beach and blown sand where all kinds of littoral subjects lurk, the 887,740 acres of which from a botanical point of view Cornwall is comprised hold probably a larger number of species than any other British county of the same size. If meteorological values be added to the map another key will have been furnished to the richness of the flora. To say nothing of the high mean bright sunshine, and of the mean range of temperature for the coldest months whereby the winters become ' languid springs,' the rainfall is so high, and taking the county as a whole so erratic, as greatly to modify the botanical features. Compared with many other English counties Cornwall's mean rainfall of 48 inches is rather great, but its peculiarity does not end there. Although only 80 miles in its greatest length there is a marked contrast between the rain- fall of the two extremes of the county. East Cornwall has an average rainfall of 55 inches and west Cornwall 43 inches. The higher figure corresponds with the greatest breadth of the county, which may be taken as 45 miles, and the lower with the narrowest section, which in one place falls below 6 miles. As will subsequently appear, the two sections so marked off have their own characteristic floras. East Cornwall may be regarded as the haunt of Rubi, and west Cornwall as the district of Leguminosa and Characea. The only islands off the Cornish coast possessing special botanical interest are the Scillies, lying 27 miles west of the Land's End. Between the flora of these islands and the mainland there is much in common, though the absence of hills, woods and rivers tells a very important tale. Nearly two-thirds of the plants growing on the mainland have been found on the Scillies. Among the absentees however are several very common species. Plants which have been found there and not on Cornish soil proper are Polygala calcarea (one specimen), Trifolium repens var. Townsendtt, Ornithopus ebracteatus, Filago spathulata^ Eleocbaris uniglumis, i 49 7