Penstemon triflorus
Contr. Herb. Franklin Marshall Coll. 1: 92, plate 8. 1895. (as Pentstemon)
Stems erect, 30–65 cm, retrorsely hairy. Leaves basal and cauline or, sometimes, basal absent or withering, not leathery to ± leathery, glabrous or retrorsely hairy along midvein and, sometimes, along margins; basal and proximal cauline petiolate, 22–120(–190) × 7–40(–65) mm, blade oblanceolate to elliptic, base tapered, margins entire or serrate to dentate, apex obtuse to acute; cauline 6–8(–10) pairs, sessile, 30–95(–115) × 7–30 mm, blade ovate to lanceolate to linear, base tapered to cordate clasping, margins entire or serrate, apex acute. Thyrses interrupted, cylindric, 5–20 cm, axis glandular-pubescent, verticillasters (3–)4–6, cymes 2–4(–6)-flowered, 2 per node; proximal bracts ovate to lanceolate, 14–50 × 6–17 mm; peduncles and pedicels glandular-pubescent. Flowers: calyx lobes ovate to lanceolate, 6.5–13 × 2.5–4.8 mm, glandular-pubescent; corolla pink to pinkish red or reddish violet, with red or crimson nectar guides, ventricose, 22–35 mm, glandular-pubescent internally, tube 8–11 mm, throat gradually inflated, not constricted at orifice, 10–13 mm diam., rounded abaxially; stamens: longer pair exserted, pollen sacs opposite, explanate, 0.9–1.2 mm, dehiscing completely, sutures smooth; staminode 17–20 mm, included or reaching orifice, 0.4–0.6 mm diam., tip straight to recurved, distal 8–12 mm sparsely to moderately pilose, hairs yellow, to 1 mm; style 18–24 mm. Capsules (7–)11–14 × 5–8.5 mm.
Distribution
Tex., n Mexico.
Discussion
Varieties 2 (2 in the flora).
Penstemon triflorus occurs largely on the Edwards Plateau, though a few populations are known from adjacent physiographic provinces in central Texas.
Selected References
None.
Key
| 1 | Cauline leaf blades ovate to lanceolate, margins sharply serrate; calyx lobes 8–13 × 3–4.8 mm; corollas 30–35 mm. | Penstemon triflorus var. triflorus |
| 1 | Cauline leaf blades lanceolate to linear, margins entire or obscurely, rarely sharply, serrate; calyx lobes 6.5–8.5 × 2.4–3.5 mm; corollas 22–30 mm. | Penstemon triflorus var. integrifolius |