Phytoneuron 2012-39: 36. 2012.
Perennials, rhizomatous. Stems erect, usually simple, (15–)25–60(–75) cm, stipitate-glandular to glandular-villous. Leaves cauline; petiole 0 mm; blade palmately veined, elliptic to ovate, ovate-lanceolate, or broadly oblanceolate, (10–)25–75(–90) × 5–35 mm, base rounded to cuneate, subclasping, margins denticulate, subentire, or entire, apex acute, surfaces stipitate-glandular to glandular-villous. Flowers herkogamous, 2–6(–10), axillary at leafy medial to distal nodes. Fruiting pedicels (25–)35–70 mm, stipitate-glandular to glandular-villous. Fruiting calyces broadly cylindric-campanulate, not inflated, 15–22 mm, stipitate-glandular to glandular-villous, tube 12–15(–17) × 9–12 mm. Corollas purple, rarely crimson, pale violet, white, pinkish white, yellowish white, or lavender, sometimes lined with red dots, bilaterally symmetric, strongly bilabiate; tube-throat funnelform, 22–28 mm, exserted beyond calyx margins; lobe apex usually truncate to shallowly convex, shallowly retuse, throat open. Styles glabrous. Anthers included, white-villous, thecae spreading. Capsules included, 6–11 mm. 2n = 16.
Phenology: Flowering Jun–Sep.
Habitat: Stream banks, springs, wet meadows, subalpine slopes, talus, crevices, ditches.
Elevation: 600–2900(–3200) m.
Alta., B.C., Alaska, Calif., Colo., Idaho, Mont., Nev., Oreg., Utah, Wash., Wyo.
Erythranthe lewisii in California occurs in Modoc, Siskiyou, and Trinity counties. California records from Shasta County and south previously identified as E. lewisii are identified here as E. erubescens. The record for E. lewisii in Alaska is documented by this collection: Hyder [noted on handwritten label as "New to Alaska, Standley"], damp land, 27 June 1924, K. Whited 1291 (MO).
Apparent exceptions to the characteristic flower color are these: white to lavender in Nevada (Clark County, Charleston Mountains, Train 2068, MO); pinkish white in Washington (Skamania and Yakima counties, Mt. Paddo, Suksdorf 5779, MO); white or tinged with yellow, in Wyoming (Teton County, as described by Nelson in the protologue of Mimulus lewisii var. tetonensis).