n8 COMMON WEEDS 



plants, dragging them down and choking them out. 

 In root crops also Black Bindweed (Fig. 33) may be 

 very troublesome. 



The slender twining angular stems are i to 4 feet 

 long; the leaves are somewhat heart- or arrow-shaped, 

 i to 4 inches long, and shortly stalked, with two thin 

 stipules where the stalk joins the stem ; and the flowers, 

 appearing from July to September, are very small, 

 greenish-white, in four- to ten-flowered loose terminal 

 or axillary clusters, each flower being on a very short 

 slender stalk, and giving rise to a rough, black, tri- 

 angular fruit or " seed." The flowers are quite different 

 from those of Field Bindweed, and the roots are fibrous, 

 not creeping as in the latter weed. The seeds are too 

 frequently found in samples of cereal grain, and as 

 many of them ripen long before harvest, they are also 

 plentifully shed in the field and reproduce the weed 

 in another year. " The seeds have considerable value 

 as feed for stock, for which reason screenings contain- 

 ing 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." * 



Black Bindweed may be combated in several ways : 

 (i) By ensuring a pure seed supply ; (2) by the surface 

 cultivation of corn crops as long as possible in spring ; 

 (3) by the use of the seed-catching box (p. 30) on 

 the reaper or binder at harvest time in order to destroy 

 as many of the seeds as possible ; (4) by harrowing 

 the stubble immediately after harvest, some time before 

 ploughing, in order to encourage the seeds to germinate, 

 when the young seedlings may be destroyed ; (5) by a 

 short rotation, the hoeing of root crops destroying 

 large quantities of the weed. 



Docks (Rumex sp.), described at p. 201, are an espe- 



1 Farm Weeds, Dept. Agric., Ottawa. 



