BOTANY IN the botanical investigation of any area the questions which arise are such as what plants grow in it and why ? why do these grow here and those there ? why are some scarce and local and others common and widely prevalent ? The answers are found in the con- sideration of the factors which determine the distribution of plants and their operation. Among these factors two will be dealt with here climate and soil. In estimating climate both altitude and latitude have to be taken into account, the result of their interaction being manifested in the varying gradations of temperature, humidity, etc., which they produce. Mr. Watson, in his Compendium of the Cybele Britannica, represents their combined action in his scheme of regions and zones, which, taken in ascending order, comprise two regions, the agrarian and the arctic, each subdivided into three zones, the infer-, mid- and super-agrarian, and the infer-, mid- and super-arctic. Each zone is distinguished from its neigh- bour by certain plants which are especially characteristic of it and which disappear in ascending to the zone above it. No better scheme than the above-mentioned has been put forth, nor more useful for determining the relation of the flora to the physical character of any area. In our county we have three of these zones exemplified, the two upper zones of the agrarian and the lowest of the arctic region. These therefore are treated of here. Our lowest zone, the second or mid- agrarian, the characteristic species of which are buckthorn (Rhamnus catharticus] and cornel (Cornus sanguined], may be subdivided into two, a lower, milder, warmer area south and east of Derby and from Burton along the course of the Trent, ranging from about 90 feet to 250 feet, in which the following plants reach their upper limit : Diplotaxis muralis, Geranium pusillum, Vicla lathyroides, bryony (Bryonia dioica], CEnanthe Jluviatilis, teazle (Dipsacus sihestris], Filago minima, water violet (Hottonia palus tris), Utricularia vulgar is, Polygonum minus, Rumex maritimus and' R. pulcher, Calamagrostis lanceolata, Festuca myurus ; and a higher area comprising the valleys and hillsides, from 250 feet to 1,050 feet, in the central and south-western part of the county, with spindlewood (Euonymus europceus), buckthorn (Rhamnus catharticus), maple (Acer campestre], convolvulus (C. sepium), black bryony (Tamus communis) as characteristic species which reach their limit here. Our next zone in the ascending scale is the super-agrarian, where buckthorn and cornel die out and bracken (Pteris aquilina) and cultiva- 39
