WEEDS OF THE BUCKWHEAT FAMILY. 



65 



Fig. 31. (After Vasey.) 



Common in moist soil, 

 especially that near the 

 margins of lakes, ponds 

 and marshes. July-Oct. 

 Stems stouter than our 

 other forms and when old 

 very hard and woody. 

 Seeds frequent in those of 

 clover cut from lowlands. 

 The leaves are often spot- 

 ted with a reddish lea-f- 

 spot fungus and the heads 

 are sometimes affected with 

 a smut which destroys the 

 seeds. Remedies: mowing 

 before the seeds have rip- 

 ened; hoeing, pulling and] 

 cultivating. 



20. POLYGONUM PERSICABIA L. 



Lady's Thumb. Spot- 

 ted Smartweed. Heart- 

 weed. (A. I. 2.) 



Occurs in the same places as 

 the curled dock, but less common. 

 June-Aug. The seeds of both these 

 docks are often found in clover and 

 alfalfa seed which has not been 

 properly cleaned. Where found in 

 cultivated land, both can be eradi- 

 cated only by short rotation or thor- 

 ough cultivation with hoed crops. 



19. POLYGONUM PENNSYLVANICUM L. 

 Pennsylvania Smartweed. Gland- 

 ular Persicary. (A. N. 2.) 

 Erect, simple or branched, 2-6 feet 

 high, the flower stems with numerous 

 glands ; leaves lanceolate, pointed, 2-11 

 inches long. Spikes several, short, erect, 

 cylindrical, dense flowered ; calyx dark 

 pink or rose color, 5-parted. Seeds lens- 

 shaped, $ inch long, dark, shining. 

 (Fig. 32.) 



Fig. 32. Showing the flower opened and spread apart and 

 the fruit with its two styles. (After Small.) 



nt ii 



Stem erect or ascending, simple or much branched, glabrous, 6 inche? 

 to 2 feet high; leaves lanceolate, pointed at both ends, often with a tri- 



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