Phytoneuron 2012-39: 38. 2012.
Annuals, fibrous-rooted or filiform-taprooted. Stems erect to ascending, straight or geniculate at nodes, simple or branched at proximal and medial nodes, 6–20 (–25) cm, minutely stipitate-glandular, hairs 0.1–0.3 mm, gland-tipped. Leaves usually cauline, basal usually deciduous by flowering; petiole: proximals 1–3 mm, distals 0 mm; blade palmately 3–5-veined, narrowly ovate or narrowly lanceolate to elliptic or elliptic-lanceolate, largest 8–18 (–30) × (1–) 3–7 mm, relatively even-sized, or slightly reduced distally, base attenuate to obtuse or rounded, margins entire, mucronulate, or denticulate, apex acute to obtuse, surfaces minutely stipitate-glandular, hairs 0.1–0.3 mm, gland-tipped. Flowers plesiogamous, 10–20, from medial to distal nodes. Fruiting pedicels straight, 7–18 mm, minutely stipitate-glandular, hairs 0.1–0.3 mm, gland-tipped. Fruiting calyces winged, plicate-angled, maturing ovoid-ellipsoid to campanulate or broadly urceolate, distinctly inflated, 7–11 mm, margins distinctly toothed or lobed, sparsely, minutely hirtellous, eglandular, lobes pronounced, erect. Corollas yellow to pale-yellow, sparsely red-spotted or not, bilaterally symmetric, weakly bilabiate; tube-throat cylindric, 5–8 mm, exserted 1–3 mm beyond calyx margin; limb barely widened, lobes broadly obovate, apex rounded or mucronate. Styles glabrous. Anthers included, glabrous. Capsules included, 5–9 mm.
Phenology: Flowering Jun–Jul.
Habitat: Drying edges, banks, and beds of summer-dry watercourses, near drying edges of small lakes or impoundments, often among rocks and shoreline detritus, occasionally in moist protected areas beneath low shrubs.
Elevation: 1200–1700 m.
Calif., Idaho, Nev., Oreg.
No natural occurrences of Erythranthe inflatula are known from Washington; the type collection from Klickitat County is from a cultivated plant.
Morphological and molecular data (R. J. Meinke 1995; P. M. Beardsley et al. 2004) indicate that Erythranthe inflatula originated as a hybrid between E. breviflora and E. latidens. Its geography and biology suggest that it is reproductively stable. The putative parents are geographically and ecologically separated for most of their ranges, and the range of E. inflatula is considerably broader than the relatively small region where the parents are sympatric. In the region of sympatry, however, E. inflatula may be difficult to distinguish from one or both of its putative parents. G. L. Nesom (2012g) was not able to find morphology that would distinguish the recently described Mimulus evanescens from E. inflatula.
"widened" is not a number.