Rhodora 3: 273. 1901.
Stems simple or branched, to 23 (–40) cm; branches 1–4 (or 5) pairs, ascending, from middle and distal cauline nodes; cauline internode lengths 1–3 (–5) times subtending leaves. Leaves: petiole 0–10 (–13) mm; blade long-orbiculate to triangular-ovate or oval, 2–10 (–13) mm, margins crenate to incised-crenate, teeth 1–4 (–6) pairs, apices obtuse to subacute. Inflorescences sparsely spicate, not 4-angled, beginning at node 3–7 (–10); proximal internode lengths 0.8–1.5 times bracts; bracts green or suffused with purple, as broad as leaves, ovate or oval, length not more than 2 times width, 2–7 mm, base round, abaxial surface setulose on veins, adaxial puberulent and hairs eglandular, teeth 3–5 (or 6) pairs, longer than wide, apices obtuse to acute, sinuses between teeth acute. Flowers: calyx lobes straight, apex acute; corolla white or cream, abaxial lip lilac or purple, adaxial lilac, 2.5–4.5 mm, lips equal. Capsules oval to oblong or obovate, 2.5–5 mm, apex retuse to emarginate.
Phenology: Flowering summer.
Habitat: Damp habitats near sea, sand, salt marshes, Sphagnum marshes, hummocks, ledges, grassy slopes, non-calcareous soils.
Elevation: 0–600 m.
N.B., Nfld. and Labr., N.S., P.E.I., Que., Maine.
Euphrasia purpurea Reeks ex Fernald & Wiegand is an illegitimate name that pertains here.