Phytoneuron 2012-39: 37. 2012.
Perennials, rhizomatous. Stems erect to decumbent, usually simple, weakly 4-angled, 20–60 cm, ± glandular-villous. Leaves cauline; petiole 0 mm; blade palmately 3–5-veined, elliptic to obovate, rhombic-ovate, or broadly spatulate, 50–75 × 15–26(–30) mm, base subcordate, subclasping, margins coarsely serrate, sometimes only distally, apex acute to obtuse, surfaces ± glandular-villous. Flowers herkogamous, 2–12, axillary at leafy medial to distal nodes. Fruiting pedicels 45–90(–150) mm. Fruiting calyces campanulate, weakly inflated, 20–28 mm, sparsely glandular-villosulous to stipitate-glandular, lobes triangular to ovate-triangular, apex linear-triangular. Corollas crimson, often yellow-tinged, palate ridges dark red, bilaterally symmetric, strongly bilabiate; tube-throat tubular, 25–35 mm, exserted 13–25 mm beyond calyx margin; abaxial limb spreading, adaxial erect, lobe apex truncate, often emarginate, throat open, palate ridges densely short-villous. Styles glabrous. Anthers exserted, white-villous, thecae reflexed 45º. Capsules included, 15–22 mm. 2n = 16.
Phenology: Flowering Jun–Sep.
Habitat: Stream edges and beds, flood plains, around seeps and springs, canyon bottoms, moist cliff crevices and ledges.
Elevation: 300–2600 m.
Ariz., Utah, Mexico (Baja California, Chihuahua, Durango, Sinaloa, Sonora).
R. K. Vickery (1992) noted that yellow-flowered morphs of Erythranthe verbenacea occur in a population at Vasey’s Paradise in the Grand Canyon (Coconino County), 32 miles downstream from Lees Ferry.
Populations of Erythranthe verbenacea in the Oak Creek Canyon area in southern Coconino County, Arizona, have leaves with a narrow, lateral, undulating, purple stripe across the mid lamina. The coloration is retained even in dried specimens.
In Utah, Erythranthe verbenacea is known only from the Zion Canyon area.
Molecular (P. M. Beardsley et al. 2003) and morphological (G. L. Nesom 2014b) data indicate that Erythranthe verbenacea is sister to E. eastwoodiae.