Stems 0.5-3 dm, in well developed plants at least some of the internodes more than 3 times as long as the lvs; lvs several pairs, ovate, 5-10(-15) mm, with 3-5 acute or obtuse teeth on each side, ±hairy on both surfaces, the bracts basically similar; cal crisp-hairy, its broadly triangular lobes ultimately 2.5-3 mm; cor mostly 4-6 mm, white with purple lines, essentially intermediate in size and form between that of no. 1 [Euphrasia officinalis L.] and those of nos. 3 [Euphrasia randii Rob.] and 4 [Euphrasia oakesii Wettst.]; fr ±hairy; 2n=44. Streambanks, bogs, and other wet places; Lab. and Nf. to Alas., s. to Me., n. Mich., ne. Minn., and Mont. July-Sept. (E. arctica var. d., assuming a circumboreal distribution for E. arctica, but that name may not properly apply, the nomenclature confused)
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.