Epilobium leptophyllum Raf.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.
Species Description - Much like no. 5 [Epilobium palustre L.], but more hairy, avg more robust, and with consistently narrow lvs; pls 2–10 dm, often freely branched and with numerous lvs; stems canescently strigillose-puberulent nearly or quite throughout; lvs more often with axillary fascicles, mostly 1.5–7 cm × 1–7 mm, revolute, evidently strigose-puberulent across the whole upper surface and along the midrib (or across the whole surface) beneath; 2n=36. Wet meadows, bogs, and marshy ground; Nf. to Mack. and B.C., s. to N.C., Kans., and Calif. July, Aug. (E. nesophilum)
American marsh willow-herb