Fl. S.E. U.S., 1060, 1337. 1903. (as Pentstemon)
Herbs. Stems ascending to erect, 25–55(–65) cm, retrorsely hairy and glandular-villous proximally, retrorsely hairy and glandular-pubescent distally, glandular hairs sometimes sparse, not glaucous. Leaves basal and cauline, basal often withering by anthesis, not leathery, sparsely to densely pubescent, sometimes also with scattered glandular hairs, abaxially, sparsely pubescent adaxially; basal and proximal cauline 20–120(–180) × 5–35(–40) mm, blade spatulate to obovate or ovate, base tapered, margins subentire or ± serrate or dentate, apex rounded to obtuse or acute; cauline 4–8 pairs, sessile, 22–100 × 4–24 mm, blade ovate to lanceolate, base truncate to clasping, margins subentire or ± serrate or dentate, apex acute to acuminate. Thyrses interrupted, conic, 5–26(–30) cm, axis sparsely to densely glandular-pubescent, verticillasters 3–8, cymes 2–8(–16)-flowered, 2 per node; proximal bracts lanceolate, 7–72 × 2–22 mm, margins entire or ± dentate; peduncles and pedicels ascending, sparsely to densely glandular-pubescent. Flowers: calyx lobes ovate to lanceolate, (2–)3–5 × 1–3 mm, sparsely glandular-pubescent; corolla white, sometimes tinged lavender or blue, with reddish purple nectar guides, tubular to tubular-funnelform, 16–22 mm, glandular-pubescent externally, moderately whitish or yellowish lanate internally abaxially, tube 4–6 mm, throat slightly inflated, 4–7 mm diam., 2-ridged abaxially; stamens included, pollen sacs opposite, navicular, (0.8–)1–1.2 mm, dehiscing completely, connective splitting, sides glabrous, sutures papillate; staminode 10–12 mm, exserted, 0.2–0.3 mm diam., tip straight to slightly recurved, distal 8–9 mm moderately to densely villous, hairs yellow or golden yellow, to 1.5 mm; style 12–14 mm. Capsules 5–7 × 3–5 mm, glabrous. 2n = 16.
Phenology: Flowering Apr–Jun(–Jul).
Habitat: Tallgrass prairie, limestone and sandstone glades, barrens, rocky oak-hickory woodlands.
Elevation: 10–300 m.
Ont., Ala., Ark., Conn., D.C., Ga., Ill., Ind., Iowa, Kans., Ky., Maine, Md., Mass., Mich., Minn., Mo., N.H., N.J., N.Y., N.C., Ohio, Pa., R.I., Tenn., Vt., Va., W.Va., Wis.
Penstemon pallidus is concentrated in the Central Lowlands and Ozark Plateau of the central United States. F. W. Pennell (1935) believed it to be native there, having spread eastward as a result of human activities, as in Ontario.
Penstemon brevisepalus, which has been synonymized with P. pallidus by many authors, is treated here as a distinct species. Characters distinguishing the species are discussed under 147. P. brevisepalus.
Some specimens from north-central Arkansas and north-central Missouri are morphologically intermediate between Penstemon pallidus and P. arkansanus.