PLATE 43. 

 WILD BUCKWHEAT, Polygonum Convolvulus, L. 



Other English name : Black Bindweed. 



Introduced. Annual. A twining vine with rather rough branching 

 stems and thin, smooth, arrow-head-shaped leaves. Flowers greenish, droop- 

 ing, on short slender pedicels, in small clusters from the axils of the leaves 

 and in loosely flowered terminal racemes. Calyx 5-parted, persistent, close- 

 ly wrapped around the single dull black triangular seed (achene) [Plate 56, 

 fig. 75 natural size and enlarged 4 times], which is about J-inch long, 

 bluntly pointed at the apex, and almost twice as long as broad, widest just 

 above the middle; embryo club-shaped, small, curved and lying along one 

 angle of the seed in a groove in the large central mealy mass. 



Time of Flowering : From June throughout the summer, the seeds ri- 

 pening irregulirly from about the beginning of July. 



Propagation ; By seed. 



Occurrence -. General. Most injurious in the Prairie Provinces. 



Injury : Twining around the stems of the small grains, binding them 

 together, pulling them down and choking them out, also a great nuisance in 

 potato fields. The seeds begin to ripen long before all grain crops, and in 

 that way land devoted to grain crops for several years becomes badly infested ; 

 the seeds are one of the most abundant impurities in grain sent to the mar- 

 ket, particularly in wheat and oats. The seeds have considerable value as 

 feed for stock, for which reason screenings containing these and other weed 

 seeds are often carried back from the elevators by farmers and fed without 

 grinding or scalding, which is a dangerous practice. 



Remedy : Harrow or cultivate stubbles directly after harvest, so as to 

 cover up and encourage the germination of as many seeds as possible in 

 autumn. Tho young plants will be killed by frost. Those seedlings which 

 rerminate in spring must be destroyed by cultivating before seeding or by 

 harrowing after the grain is up. Ploughing for summer-fallow must be 

 done earlj 7 , so as to turn down plants on stubble before the seeds ripen. 



83 



