Stems (20–)30–40(–60) cm, glabrous or scabrous proximally. Leaves (7–)10–25 pairs, (3–)5–30(–40) × 0.5–1(–2.5) mm, blade base tapered, margins glabrous or scabrous, apex acuminate to mucronate. Thyrses 6–15 cm, verticillasters 6–10, cymes 1–3-flowered; proximal bracts linear, 6–27(–33) × 0.3–1.5 mm; peduncles and pedicels glabrous or scabrous. Flowers: calyx lobes ovate, 1.5–3.5 × 1–1.5 mm; corolla pink (limb milky pink or milky white), lined internally abaxially with reddish purple nectar guides, salverform, (14–)16–22(–28) mm, glandular-pubescent internally in 2 lines on abaxial surface, tube 3–4 mm, throat 3–5 mm diam.; stamens included, pollen sacs 0.5–0.6 mm; staminode 7–9 mm; style 8–10 mm. Capsules 6–9 × 3–5 mm.

Distribution

w United States, n Mexico.

Discussion

Varieties 2 (2 in the flora).

G. T. Nisbet and R. C. Jackson (1960) reported natural hybrids between Penstemon ambiguus and P. thurberi from Lincoln and Socorro counties, New Mexico.

Some Native American tribes used Penstemon ambiguus as a drug or ceremonial plant (D. E. Moerman 1998).

Selected References

None.

Lower Taxa

Penstemon ambiguus var. ambiguus, Penstemon ambiguus var. laevissimus

Key

1	Stems scabrous proximally; leaf blade margins scabrous.	Penstemon ambiguus var. ambiguus
1	Stems glabrous; leaf blade margins glabrous or scabrous.	Penstemon ambiguus var. laevissimus