Fig. 407: Polygonum pensylvanicum: a, habit, x %; b, ocrea, x 2; c, peduncle en- 

 larged; d, part of flowering spike, x 4; e. perianth enclosing mature fruit, x 7; f, achene, 

 X 7; g, cross section of achene, x 7. (Courtesy of R. K. Godfrey). 



