Fig. 417: Polygonum hydropiperoides var. opelousanum: a, habit, x %; b, ocrea, 

 X 1; c, part of flowering spike, x 2; d and e, two views of perianth enclosing mature 

 fruit, X 8; f, achene, x 8; g, cross section of achene, x 8. (Courtesy of R. K. Godfrey). 



