Epilobium palustre L.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.
Species Description - Perennial from very slender, nearly naked stolons, each ending in a turion from which the stem of the next year arises; stems slender, simple or branched, 1–5(–8) dm, canescently strigose-puberulent in the infl, but the middle and lower part usually more sparsely strigillose-puberulent, often in vertical strips; lvs all opposite, or the upper more often alternate, sessile or nearly so, sometimes with axillary fascicles, broadly linear to more often lanceolate or lance-linear, 2–7 cm × 2–15 mm, entire or nearly so, often revolute, not very hairy, the lower side commonly puberulent along the midrib but otherwise glabrous or nearly so, the upper side glabrous or with a few scattered hairs esp. along the midrib; infl usually nodding in bud, but soon erect; fls short-pedicellate in the upper axils, the pedicels elongating to 0.5–2.5 cm in fr; pet white to pink or lilac, 4–6 mm, evidently notched; 2n=36. Wet low ground; circumboreal, s. in Amer. to Pa., Wis., Colo., and Nev. July, Aug. (E. oliganthum)