250 PASTORAL AND AGRICULTURAL BOTANY 



son's Curse, in Australia. It is a biennial arising from a thick taproot 

 and with rough, bristly hairy stems and leaves. The stiff bristles arise 

 from fine red, tubercles which speckle the stem. Hoeing, or the use of 

 the cultivator the first season of its growth, is beneficial, if no seeds are 

 allowed to form. 



Horse Nettle (Solatium carolinense) . The deep-seated rootstocks 

 are most tenacious of life (Fig. 105). An Indiana farmer states that they 

 will live ten years under a heap of sawdust and grow, as soon as this 

 covering is removed. Sheep are the only grazing animals that will touch 

 the plant. The trailing stems and broad leaves of the plant are charac- 



FIG. 106. Two specimens of Ox-eye daisy (Chrysanthemum Leucanthe.mum var. 

 pinnatifidum) in a sand-lot at Belmar, N. J., June 23, 1919. The right hand plant had 

 a spreading habit with stiff, stout bluish-green stems margined with purple lines. It 

 had 79 compact heads with crowded rayflowers of medium length. The left hand plant, a 

 third taller than the other, was of a light green color with broader heads, the ray florets 

 narrower, longer and more pointed. The stems were less stout, more flexuous and the 

 whole plant with 76 head-bearing stems. These are probably mutants of the common 

 field daisy. 



terized by sharp yellow prickles. The flowers with pale- violet, rotate 

 corollas are borne in open cymose clusters. It forms a small, yellow berry 

 full of flat straw-colored seeds. If the area where it grows is not large, it 

 may be killed by the use of hot brine, caustic soda, or kerosene. The 

 production of seeds should be prevented and the plants frequently cut up 

 with hoe, or spade. Salt on the cut surfaces will retard growth. The 

 rootstocks may be destroyed by short rotations, alternating thoroughly 

 cultivated crops. Two or three seasons of continuous effort are required 

 to suppress this pest. 



Yellow Toad-Flax (Linaria vulgaris). The deep, running rootstocks 

 of this weed make it difficult to suppress. The plant grows about eighteen 



