Herbs. Stems ascending to erect, 30–80 cm, retrorsely hairy and sparsely to densely glandular-villous, not glaucous. Leaves basal and cauline, not leathery, glabrous or sparsely glandular-lanate along midveins, rarely moderately glandular-lanate; basal and proximal cauline 20–126 × 4–16 mm, blade spatulate to oblanceolate, lanceolate, spatulate, or elliptic, base tapered, margins entire or serrate to dentate, apex rounded to obtuse or acute; cauline 5–8(–10) pairs, sessile or short-petiolate, 20–130 × 2–30 mm, blade lanceolate to oblanceolate, base clasping or tapered, margins finely to coarsely serrate or dentate, apex acute to acuminate. Thyrses interrupted, conic, 6–37 cm, axis glandular-pubescent to glandular-lanate, verticillasters (3 or)4–8, cymes 2–11(–15)-flowered, 2 per node; proximal bracts lanceolate to linear, 8–60 × 1–6 mm, margins entire or ± serrate to dentate; peduncles and pedicels ascending, glandular-pubescent to glandular-lanate. Flowers: calyx lobes ovate to lanceolate, 4–7 × 1.5–2.3 mm, glandular-pubescent; corolla lavender or purplish, with or without faint violet nectar guides, bilabiate, personate, tubular, 20–26(–28) mm, glandular-pubescent externally, moderately to densely white-villous internally abaxially, tube 6–7 mm, throat slightly inflated, 6–8 mm diam., 2-ridged abaxially; stamens included, pollen sacs opposite, navicular to subexplanate, 0.8–1 mm, dehiscing completely, connective splitting, sides glabrous, sutures papillate; staminode 13–16 mm, exserted, 0.6–0.7 mm diam., tip straight, distal 11–14 mm moderately to densely villous, hairs yellowish, to 1.2 mm; style 16–18 mm. Capsules 6–9 × 5–6 mm, glabrous. 2n = 16.
Phenology: Flowering May–Jul.
Habitat: Sandy or rocky woods, rocky fields, bluffs, cliffs.
Elevation: 10–200 m.
Ont., Que., Conn., Del., D.C., Ill., Ind., Ky., Maine, Md., Mass., Mich., N.J., N.Y., Ohio, Pa., R.I., Tenn., Vt., Va., W.Va., Wis.
Penstemon hirsutus occurs widely in the northeastern United States, and in southern Ontario and Quebec. Its long, tubular, personate corollas and herbage with some stellate hairs may indicate a close relationship with P. oklahomensis and P. tenuiflorus.