J. Bot. Res. Inst. Texas 6: 1, figs. 1, 2. 2012.
Herbs. Stems ascending to erect, 40–70 cm, spreading-puberulent or retrorsely hairy proximally, glandular-pubescent distally, not glaucous. Leaves basal and cauline, not leathery, glabrate or puberulent; basal and proximal cauline 20–70 × (5–)9–20 mm, blade oblanceolate, base tapered, margins entire or ± serrate or crenate, apex obtuse to acute; cauline 6–9 pairs, sessile, 120–150 × 30–40 mm, blade oblong to lanceolate or ovate-lanceolate, base tapered to clasping, margins serrate to dentate, apex acute to acuminate. Thyrses interrupted, conic, 5–20 cm, axis glandular-pubescent, verticillasters 4–7, cymes 3–7-flowered, 2 per node; proximal bracts ovate-lanceolate to lanceolate, 16–60(–80) × 3–45 mm, margins entire or serrate; peduncles and pedicels ascending, glandular-pubescent. Flowers: calyx lobes lanceolate, 4–5.5 × 0.8–1.2 mm, glandular-pubescent; corolla pale lavender to nearly white, with violet nectar guides, tubular-funnelform, 10–16 mm, glandular-pubescent externally, sparsely white-lanate internally abaxially, tube 6–7 mm, throat gradually inflated, 5–7 mm diam., slightly 2-ridged abaxially; stamens included, pollen sacs opposite, navicular, 0.8–1 mm, dehiscing completely, connective splitting, sides glabrous, sutures papillate; staminode 7–8 mm, reaching orifice or slightly exserted, 0.3–0.5 mm diam., tip straight to slightly recurved, distal 4–5 mm moderately to densely pilose, hairs golden, to 1.2 mm; style 9–12 mm. Capsules 5–6 × 3.5–4 mm, glabrous.
Phenology: Flowering May.
Habitat: Calcareous soils, juniper-oak-hickory woodlands.
Elevation: 200–300 m.
Penstemon kralii is known from the southern Cumberland Plateau. It has been collected in Blount, Jackson, Madison, and Morgan counties, Alabama, and in Franklin County, Tennessee.