Fig. 415: Polygonum hydropiperoides var. setaceum: a, habit, x %'. b, ocrea, x 1; 

 c, part of flowering spike, x 3; d, perianth enclosing mature fruit, x 8; e, achene, x 8; 

 f, cross section of achene, x 8. (Courtesy of R. K. Godfrey). 



