MICHIGAN WEEDS. 



307 



Fig. 33 (33). 



Erect Knot weed. Polygonum erectum L. 

 Annual, smooth, stem erect, usually simple; 

 leaves oval, obtuse, 13-60 mm. long; flowers 

 yellowish-green. 



When compared with P. aviculare, it is taller 

 with larger leaves and larger fruit. Seldom a 

 weed of any importance; native of this country. 



Fig. 34 (34). 



Smart- weed. Polygonum Hydropiper L. 

 A smooth, reddish, peppery, erect or spreading 

 annual, 30-60 cm. high; leaves narrow, 2-8 cm. 

 long; spikes nodding, interrupted, as long as 

 the leaves; flowers mostly greenish; achene 

 2-3-sided, dull, granular. Wet land; introduced 

 from Europe into this section; possibly indi- 

 genous in the northwest. 



