PLATE 4. 



TUMBLING MUSTARD. Sisymbrium altissimum, L. 



Other English name : Tall Sisymbrium. 



Other Latin namea : Sisymbrium sina-pistrum, Crantzj Sisymbrium 

 /KiK/ionicum, J acq. 



(Noxious: Dom., Man., N.W.) 



Annual and sometimes winter annual. Introduced into the Prairie 

 Provinces from Central and Southern Europe about 1887. Two to six feet 

 high; stem branching, the lower part and the root leaves downy and glandu- 

 lar, with a musky odour. Upper part of the stem and the much divided 

 leaves smooth. The young plants form a rosette of soft pale green downy 

 leaves, shaped much like those of the Dandelion. On the flowering plants the 

 leaves change very much in shape from lue root up, no two being alike. 

 Flowers pale yellow, ^ inch in diameter, cros.s-shaped as in all the mem- 

 bers of the Mustard and Cress family. Seed pods 2 to 4 inches long, very 

 slender and produced abundantly along the branches. Each pod contains 

 about 120 seeds, and a single plant has borne one million and a half seeds. 

 Seeds [Plate 53, fig. 3 — natural size and enlarged 8 times] very small 

 .^^ of an inch, olive-brown or greenish-yellow, minutely roughened 

 with mucilaginous glands, oblong, angular, truncate at the scar end, some- 

 times almost square from compression in the pod, grooves between the edges 

 of the seed leaves and between these latter and the radicle conspicuously 

 darkened. The seed leaves and incumbent radicle plainly visible through 

 the thin skin. When the seeds are ripe the whole head of the plant breaks 

 off and is blown across the prairie, scattering the seeds far and wide. The 

 seeds, as in many "tumbling weeds," are not very easily shed from the tough 

 pods, consequently a head of this weed may blow about on the prairie for a 

 whole winter, dropping a few seeds at intervals for many miles. 



TtTTie of Flowering : June to July ; seed ripe August. 



Propagation : By seeds. 



Occurrence : In grain fields in the West. Occasionally found along rail- 

 ways and in waste places in other parts of Canada, but not as a farm weed. 



Injury : This is a Mustard with all the bad characteristics of those 

 aggressive enemies of the farmer — enormously prolific, with great powers to 

 spread, owing to its tumbling habit; a coarse, conspicuous plant and a gross 

 feeder. The seed however is so small that with a little care it can be easily 

 cleaned from .seed grain. It does not appear to retain its vitality in the 

 soil as long as the seed of some other kinds of Mustard. 



Remedy : Hand-pull when there are only a few plants. Pay particular 

 attention to edges of fields and fire-breaks. Cultivate growing crops with 

 woeder or light harrows. 



