Phytoneuron 2012-39: 28. 2012.
Herbs, annual. Stems erect, 20–900 (–1200) mm, usually glandular-pubescent and viscid. Leaves basal and cauline, basal in rosette, cauline gradually reduced distally; petiole present proximally, usually absent distally; blade ovate, obovate, elliptic, or oblanceolate, 5–60 (–85) × 1.5–25 (–32) mm, margins entire or largest irregularly serrate, plane, apex rounded to obtuse, surfaces: proximals nearly glabrous, distals glandular-pubescent. Pedicels 2–5 (–8) mm in fruit. Flowers 2 per node, or 1 or 2 per node on 1 plant (1 per node on depauperate plants), chasmogamous. Calyces symmetrically attached to pedicels, inflated in fruit, (7–) 9–25 (–27) mm, glandular-pubescent and viscid, lobes often spreading in fruit, unequal if calyx large, apex acute to attenuate, ribs prominent, purplish, intercostal areas white. Corollas magenta, throat often darkening near floor, without dark spots, palate ridges or floor white, usually magenta-speckled, tube-throat 10–30 mm, limb 6–20 mm diam., not bilabiate. Anthers included, glabrous. Styles glandular-puberulent. Stigmas exserted, lobes unequal, abaxial 2–3 times adaxial. Capsules 8–20 mm. 2n = 16.
Phenology: Flowering Apr–Jul.
Habitat: Granite outcrops, slopes with decomposed granite soils.
Elevation: (100–)300–1700(–2000) m.
Diplacus bolanderi is scattered and uncommon through most of California (with concentrations in the southern North Coast Ranges and Central Sierra) and apparently is disjunct in Jackson County, Oregon.
Diplacus bolanderi is highly variable in height, leaf size, corolla size, and calyx size. Identity is unmistakable in larger plants; the inflated calyx with lobes strongly unequal in length usually is helpful in identification of smaller plants.