2i6 THE BOOK OF NATURE STUDY 



with the lighter soils, as are Gorse and Broom among shrubs. 

 Foxgloves, Bracken, and Heather are typical plants. Ornithopus 

 and one or two vetches are common, though the majority of 

 leguminous plants do not grow freely when carbonate of lime 

 is lacking. Among weeds, Spurrey, the small Sorrel Dock, Corn 

 Marigold, and Knawel are characteristic ; the two former being 

 particularly indicative of lack of carbonate of lime in the soil. 



CALCAREOUS SOILS. Not all soils derived from chalk or lime- 

 stone are calcareous, even though the rock may be found unaltered 

 a very short distance below. Carbonate of lime is so readily 

 dissolved by natural waters charged with carbonic acid from the 

 soil that in many cases it has been washed out of the thin layer 

 of surface soil existing on some of the calcareous formations. 

 Hence it is necessary, when studying the vegetation of an area 

 resting on chalk or limestone, to make certain of the presence 

 or absence of carbonate of lime in an ostensibly calcareous soil 

 before drawing any conclusions from the occurrence of a given 

 plant. 



Calcareous soils are generally dry, warm and early ; most 

 leguminous plants flourish well on them, notably Lucerne and 

 Sainfoin in the warmer parts of the country. They are healthy 

 for stock, though snails, slugs, and certain insect pests are trouble- 

 some to crops, and in the pastures worms are always specially 

 abundant. 



The most characteristic features of the vegetation on calcareous 

 soils are its extreme variety and floriferousness ; on no other soil 

 can so many brilliantly coloured and strongly scented flowers 

 be found at all periods of the year. The Beech, Yew, and Wild 

 Cherry are typical trees ; the hedgerows are full of characteristic 

 shrubs like Dogwood, the Mealy Guelder Rose or Wayfaring tree, 

 Clematis, the Beam tree, and Sweetbriar. Juniper occurs on the 

 open downs, as also does Box in the few cases where it is truly 

 wild. The Horseshoe Vetch, Burnet, the Dropwort, some of the 

 gentians, various orchids, and Sheep's Scabious and many labiates 

 are almost confined to calcareous pastures ; while Chicory and 

 Wild Parsnip are common in waste places. Several grasses are 

 confined to calcareous soils, as are several ferns to calcareous 



