MICHIGAN WEEDS. 



353 



Fig. 104 (96). 



Ball Mustard. Neslia paniculata (L.) 

 Desv. A slender, branching annual, pubescent 

 with star-shaped hairs, leaves oblong, sagittate; 

 flowers in racemes; pods nearly spherical, 2-3 

 mm. in diameter. 



Introduced from Europe into British Prov- 

 inces of the northwest where it is very aggres- 

 sive and may soon find its way to Michigan. 



Fig. 105 (97). 



Tumbling Mustaid. Tall Mustard. 



Sisymbrium altissimum L. An erect, smooth, 

 branching annual, 60-120 cm. high; leaves 

 deeply pinnatifid; flowers pale yellow; pods 

 narrow, stiff, diverging, 5-10 cm. long; seeds 

 minute and enormously abundant; when mature 

 the plant loosens from the soil becoming a first- 

 class tumble weed; not yet abundant in Mich- 

 igan but will soon become so. 



Naturalized from Europe, with all the bad 

 characteristics of a mustard. 



