NUMBER AND KINDS OF WEEDS ON DIFFERENT SOILS 667 



horsetail. Of grass land weeds there are listed (Colchicum autum- 

 nale), buttercups, leguminous weeds, gorse (Ulex) broom, rest har- 

 row (Ononis spinosa), dyer's green weed (Genista tinctoria), wild 

 carrot, burdock, knapweed (Centaur -ea nigra), thistles (Girsium 

 arvense, C. acaule, C. lanceolatum, G. palustris), cotton thistle 

 (Onopordum acanthium), daisy (Bellis perennis), ox-eye daisy, rag- 

 wort (Senecio jacobaea), plantains, yellow rattle, self-heal (Prti- 

 nella vulgaris), docks, sorrel (Rumex acetosa, B. acetosella), sting- 

 ing nettle (TJrtica dioica) ; grasses: bent grass (Agrostis alba) tus- 

 sock grass (Aira caespitosa), Yorkshire fog (Holcus lanatus), 

 creeping soft grass (H. mollis), quaking grass (Briza media), bar- 

 ley grass (Hordeum pratense), and the bracken (Pteris aquilina), 

 horsetail, and mosses. 



Fig. 521. Common Porcupine or Needle Grass (Stipa spartea). A weed native 

 to gravel soil, soon succumbs to cropping, a, single spikelet ; b, fruit with 

 sharp pointed callus. 



(Lamson-Scribner, U. S. Dept. Agr.) 



