36 MINNESOTA WEEDS 



Smartweed {Polygonum persicaria L.) 



Other common name. —Lady's thumb. 



Description. — There are four common smartweeds in this State, 

 but owing to the nature of this species and to the size of its seed it 

 is probably the one most commonly found in Minnesota crop seeds. 



This plant is an annual growing from twelve to twenty inches 

 high. The leaves are short stalked and are narrow and pointed. 

 Often the leaves are marked with a dark triangular spot near the 

 middle. The plant is sparingly branched and che flowers are of a 

 pinkish hue and not very large. The seeds are either lens-shaped or 

 triangular. The triangular-shaped seeds are less common. The 

 seeds are generally jet black and very shiny. Some of the more 

 immature seeds, however, are reddish brown. A pinkish or brown- 

 ish sheath often surrounds the seed. These seeds are most commonly 

 found in red clover, but occur in grass seed and cereals also. They 

 are separated with ease from cereals, but with greater difficulty from 

 red clover. Flowering continues during the latter part of July to 

 August and the seeds usually ripen during August and September. 

 The weed requires rich, moist soil, thrives well in swamps or along 

 streams and lakes and is quite generally distributed throughout the 

 State. 



Eradication.— Smartweed is not usually troublesome in culti- 

 vated fields. If low land and marshes are drained and put under 

 cultivation, the weed will disappear. In low pastures or meadows 

 that can not be drained or tilled the smartweed should be cut fre- 

 quently enough to prevent seeding. Grasses adapted to the condi- 

 tions should be sown thickly to crowd it out. 



Lamb's Quarters (Chenopodi um album L.) 



Other common names. — White goose-foot, pigweed. 



Description. — Lamb's quarters is an annual plant growing from 

 two to three feet high or in some cases six feet high. The entire 

 plant has a sort of silvery grayish appearance, and is more or less 

 covered with a white mealy substance This plant varies greatly 

 in appearance. Often it is much branched, but some plants have 

 very few branches. The leaves are whitish green, coarsely toothed 

 and have long stalks. The silvery coating is more prominent on the 

 under side of the leaf. The flowers are clustered into conspicuous 

 green balls. The seeds vary in appearance depending on the degree 

 of ripeness and the manner in which they have been threshed out. 

 When all the coat has been removed, the mature seed is black and 

 shiny, resembling the pigweed seed. It is lens-shaped and about 



