Publication: Fl. S.E. U.S. 379. 1903.

Origin:

selected vouchers: WTU

Notes: Treated as a variety of Polygonum hydropiperoides by H&C.

FNA5: "C. B. McDonald (1980) showed that Persicaria setacea is closely related to P. hirsuta and P. hydropiperoides. Hybrids between P. setacea and P. hirsuta have been produced experimentally but appear to be rare in the wild. Persicaria setacea and P. hydropiperoides occasionally occur in mixed populations but do not hybridize (McDonald). Persicaria setacea sometimes intergrades morphologically with P. hydropiperoides, especially in New England. Specimens of P. setacea without the characteristic ascending or spreading hairs on the ocreae usually can be distinguished from P. hydropiperoides by the extent of adnation of the hairs to the ocreae—up to one-third their lengths in P. setacea, but one-third to two-thirds their lengths in P. hydropiperoides."

References: (none)