Penstemon watsonii

Herbs. Stems ascending to erect, 25–60 cm, glabrous or sparsely puberulent, not glaucous. Leaves essentially cauline, basal absent or poorly developed, not leathery, glabrous or puberulent; cauline 4–8 pairs, short-petiolate or sessile, 30–70(–80) × 8–18(–35) mm, blade oblanceolate to lanceolate, base tapered or clasping, margins entire, apex obtuse to acute. Thyrses continuous or interrupted, cylindric, (1.5–)5–16 cm, axis ± retrorsely hairy, verticillasters 2–6(–10), cymes (2–)6–14-flowered, 2 per node; proximal bracts lanceolate to linear, rarely ovate, 3–60 × 1–23 mm, margins entire; peduncles and pedicels ascending to erect, ± retrorsely hairy. Flowers: calyx lobes broadly ovate, 1.8–3(–3.5) × 1.4–2 mm, apex obtuse to acute or short-cuspidate, glabrous; corolla blue to violet or purple, with faint reddish purple nectar guides, funnelform, 12–16(–18) mm, glabrous externally, sparsely white-villous internally abaxially, tube 4–5 mm, throat gradually inflated, 3–6 mm diam., 2-ridged abaxially; stamens included or longer pair slightly exserted, pollen sacs opposite, navicular, 0.9–1 mm, dehiscing completely, connective splitting, sides glabrous, sutures papillate; staminode 8–9 mm, reaching orifice, 0.2–0.3 mm diam., tip slightly recurved, distal 3–4 mm moderately to densely villous, hairs golden yellow, to 1 mm; style 9–13 mm. Capsules 4–7 × 3.5–5 mm, glabrous. 2n = 16.

Phenology: Flowering May–Aug.
Habitat: Dry, rocky slopes, sagebrush shrublands, pine-oak and pine woodlands.
Elevation: 1700–3200 m.

Ariz., Colo., Idaho, Nev., Utah, Wyo.

Discussion

Penstemon watsonii is known from mountain ranges throughout the Intermountain Region. Penstemon laxus, which has been included as a variety of this species, has corollas 2–3 mm in diameter and densely white-villous internally abaxially, and is known from south-central Idaho north of the Snake River. Penstemon watsonii does enter extreme south-central Idaho but is not known to occur north of the Snake River.

Selected References

None.

Lower Taxa