A. R. Horwood — Rock-soil and Plant Distribution. 11 



different formations are exposed, as where Pre-Cambrian rocks with 

 birch wood and Aira flexuosa adjoin red marl tracts. A feature of the 

 sandstones is the occurrence of such nrenophilous plants as Jirythrcea, 

 and where the soil is more calcareous, of Scahiosa columbaria and 

 Gentiana amarella. 



In the case of the Rhsetics the outcrop is so small and the 

 individual beds so thin that plants are not confined to a zonal 

 arrangement as in the overhing Lias. 



In the Lower Lias there are limestone bands which may be indi- 

 cated by sucli plants as Poterium sa7igia'sorba, Pimpinella mxifraga, 

 Caucalis nodosa, Canmi segetum, Cardmis nutans, Cnicus acaulis, etc. 



Ironstone bands, or beds rich in iron, are indicated by the dominance 

 of Rumex acetosa. 



Clayey beds are revealed by the predominance of Rammculus 

 jicaria, Lotus corniculaius, Conopodium denudatum, Scahiosa succisa, 

 I'ussilago, Petasites, Jancus congloyneratus, RJmianthus, Ajuga 



In the Margaritatus beds there are sandy liorizons which, are 

 characterized by JJlex, Stellaria graminea, Galium saxatile, Polygala 

 vulgaris, Mercurialis perennis, Potentilla erecta. 



Some more clayey beds are indicated by Pedicularis sylvatica, 

 Lamiiim galeohdolon, Primula vulgaris, Saxifraga granulata, Galium 

 uliginosum. 



Lime bands are indicated by Reseda luteola, Silene noctiflora, Poterium 

 sanguisorba, etc. In the Rock-bed there are sandy beds upon which 

 Eropliila vulgaris, Cerastiumsemi-decandrum, Geraniummolle, Taraxacum 

 erythrospermum, Myosotis versicolor, Veronica arvensis are particularly 

 abundant. On the purely clayey beds Ceradiuui glomeratum, Jfalva 

 moschata, Trifulhcm repens, Lathyrus 2)>'(itensis, Anthriscus sylvestris, 

 Stachys sylvalica, Tamus communis, etc., are characteristic. 



The Chalk plants Papaver RJmas, Viola hirta, Poterium sanguisorba, 

 l^xhium vulgare, Linaria vulgaris indicate bands of limestone, and so 

 also do the following limestone plants : Pimpinella magna, Centaurea 

 scahiosa. Arena prate^isis, Koeleria cristata. It is generally characterized 

 by Myosotis colli?ia, Cerastium arrense, Carduus nutans, J/alva moschata. 

 Chrysanthemum segetum, Scahiosa arvensis, Caucalis nodosa. Thymus 

 serpyllum, Galeop.sis Tetrahit, Silene noctiflora. 



The Infeiior Oolite is characterized by beech and ash woods 

 generally. Typical plants are Uelianthemum chamcecistus, Asperula 

 cynanchica, Hippocrepis comosa, Campanula glomerata, Verbascutn 

 lychnitis, Carduus 7iutans, Carlina vulgaris, Calamintha acinos, 

 Centaurea scahiosa, Filago germajiica, Galium mollugo, Anemone Pulsa- 

 tilla, Geranium columbinum. Orchis pyramidalis, 0. ustulata, Scahiosa 

 columbaria, Galium erectum, Ononis repens. Origanum vulgare, Cepha- 

 lanthera rubra, Senecio campestris, Tier minium tnonorchis, Bromus 

 erectus, Brachypodiiim pinnatum. 



The flora of the Northampton Sand is akin to that of the INFarlstone, 

 and Scahiosa arvensis, Senecio Jacoha:a, Centaurea scahiosa, Carduus 

 nutans distinguish it from that of the Upper Lias. 



Boulder-clay consists in a large measure of clay with irregular 

 patches of sand. These can be distinguished by the plants which 

 respectively prefer clay or sand. On clayey beds the following are 



