48 FARM WEEDS OP CANADA 



WILD BUCKWHEAT (Polygonum Convolvulus L.) 



Other English name : Black Bindweed. 



Introduced from Europe. Annual. A twining vine with 

 rather rough branching stems and thin, smooth, arrow-shaped 

 leaves. Flowers greenish, drooping, on short slender stalks, in 

 small clusters, arising from the axils of the leaves, and in loosely 

 flowered terminal racemes. Calyx 5-parted, persistent. 



The seed (Plate 72, fig. 11) is dull, black, triangular, about 

 1/8 inch long, bluntly pointed at the apex and almost twice as long 

 as broad, widest just above the middle; the germ is club-shaped, 

 small, curved and lies along one angle of the seed in a groove. 

 When found in commercial grain the seed is often without its 

 black coat and appears naked, white, wax-like, with slightly 

 rounded angles. 



Time of flowering: From June throughout the summer, the 

 seeds ripening irregularly from about the middle of July. 



Propagation : By seeds. 



Occurrence: General in cereal crops throughout Canada. 

 Most prevalent in the Prairie Provinces. 



Injury: A pest in fields of cereal grain. The vines twine 

 about the stems for support and interfere with the reaping 

 machinery. The crop, when matted with this weed, is more apt 

 to lodge during a storm and when once down is not able to re- 

 cover. Seeds embedded deeply in the soil germinate late in the 

 season, when the general cultivation of hoed crops is no longer 

 practicable. Thus the plant is a nuisance in fields of potatoes, 

 field roots and corn, where it seeds freely in the autumn months. 

 Although the seeds from the early bloom have ripened and drop- 

 ped before or during the harvesting of grain crops, they are fre- 

 quently present in large quantities in commercial wheat and oats. 

 In addition to reducing the yield, the grading and market value 

 of the grain is depreciated by their presence. 



