DISTRIBUTION OF WEEDS 



37 



(Sonchus arvensis] (Fig. 17) it is much stouter, while in colts- 

 foot (Tussilago farfara) (Fig. 18) it is sometimes as thick as a 

 finger, rather fleshy, and may strike down several feet into the 

 soil, and then turn horizontally instead of creeping just below 

 the surface. 1 As branches are sent up at frequent intervals a 



FIG. 21. BULBOUS BUTTERCUP (Ranunculus bulbosus). 



A. Aerial Shoot. C. Bud from which new Plant will arise. 



B. Swollen Base of Stem. D. Roots. 



single coltsfoot plant is capable of covering a very large area 

 of ground, and the deep driven stems are exceedingly diffi- 

 cult to eradicate. Woodwax (Genista tinctoria) ,(Fig. 19) 

 possesses a very rugged woody underground stem, so full of 

 " snarls " or kinks that the weed cannot be removed from 

 pasture land by any means less heroic than ploughing up. 



1 These very thick stems do not appear in the specimen illustrated. 



