PLATE 1. 



WORMSEED MUSTARD, Erysimum cheiranthoides, L. 

 Other English name : Treacle Mustard. 



(Noxious: N.W.) 



Native. Annual and winter annual. Stems erect, simple or branch- 

 ing, six inches to two feet high. Dark green; whole plant sometimes slightly 

 hoary with very short star-like hairs. Leaves, lance-shaped, sparsely 

 toothed. Flowers bright yellow, one-fifth inch across, in terminal clusters 

 about one inch across, on gradually elongating racemes. Seed pods slightly 

 curved from half an inch to one inch long, obtusely four-angled, erect on 

 spreading pedicels. Each pod contains about twenty-five seeds. An aver- 

 age plant will ripen about 25,000 seeds. Seeds [Plate 53, fig. 1 twice nat. size 

 and enlarged 8 times], variable in size and shape, many being pointed at one 

 end, rounded at the other, about T ' T of an inch long, reddish yellow, with 

 a dull surface, but almost destitute of mucilage. Scar end darkened. 

 Lladicle conspicuous and incumbent, that is lying down the back of 

 one of the seed leaves, which are plainly recognizable in the dry seed. The 

 taste of the seeds is very bitter, which renders them unpalatable to stock, 

 and it is claimed by some feeders that they are very injurious. This conten- 

 tion, however, is not borne out by recent experiments at Port Arthur, where 

 large quantities have been fed to sheep without any injury. 



Time of Flowering: June to autumn; seeds ripe July to frost. 

 Propagation : By seeds. 



Occurrence : Frequent in waste places and on cultivated land through- 

 out Canada. 



Injury : A common impurity in clover seed, also a weed of summer- 

 fallows and grain crops grown on stubble, occasionally so abundant as to 

 crowd out grain. 



Remedy : The injuries by Wormseed Mustard are mostly by those plants 

 of which the seeds germinate in autumn, and which remain on the land 

 through the winter. The destruction of these, however, is a simple mat- 

 ter by ploughing the land in fall or spring. A disk-harrow may be used 

 with good effect if the work is done early in the spring before too many new 

 roots are made. 



19 



