ARABLE WEEDS. ASSOCIATION WITH CROPS 167 



(a) Weeds Specially Associated with Temporary Grass or 

 Clover ("Seeds"). 



TABLE XII. WEEDS SPECIALLY ASSOCIATED WITH TEMPORARY 

 GRASS OR CLOVER. 



Although these weeds are so usually found among seeds 

 they are very seldom dominant, probably because the 

 smothering nature of the crop prevents any other plant from 

 usurping too predominant a position. Most of the plants are 

 very closely connected with " seeds" crops only, but campion 

 (Lychnis vespertina) and field pansy ( Viola tricolor) are 

 common among others, with a decided preference for " seeds ". 

 Both these weeds are introduced with " seeds," and they are 

 able to hold their own throughout the rotation, though 

 never present in any quantity. Campion (Lychnis vesper- 

 tina) is a great contrast to its companion, as its habit is so 

 utterly different. Most of this section are small low growing 

 plants which spread out close to the surface ofthe ground in a 

 rosette form, so that no other plant is able to crowd into the 

 ground occupied by the spreading of the weed. Campion, 

 however, is a bold, strong grower, and shoots up over the 

 head of the crop to revel in the freedom of the upper air. 



In addition to the weeds given in Table XII a number of 

 others that occur comparatively seldom are chiefly associated 

 with "seeds" crops. These all behave in the same way, and 

 disappear with the succeeding crop in the rotation. 



The chief of these are : 



Carduus nutans . 

 Cirsium lanceolatum 

 Filago germanica 

 Geranium dissectum 

 Geranium pusillum 

 Reseda lutea 



Musk thistle 



Spear thistle 



Cudweed 



Cut-leaved geranium 



Small -flowered crane's-bill 



Wild mignonette (equally common among barley). 



