Penstemon laxus

A. Nelson

Bot. Gaz. 54: 147. 1912. (as Pentstemon)

Common names: Lax beardtongue
Synonyms: Penstemon watsonii subsp. laxus (A. Nelson) D. D. Keck
Treatment appears in FNA Volume 17. Treatment on page 211. Mentioned on page 187, 219, 227.

Herbs. Stems ascending to erect, 30–70 cm, ± retrorsely hairy, not glaucous. Leaves essentially cauline, basal leaves absent or poorly developed, not leathery, glabrous, sometimes ± puberulent; cauline 4–8(–10) pairs, sessile, 30–90 × 4–17 mm, blade lanceolate, base tapered, margins entire, apex acute. Thyrses continuous or interrupted, cylindric, (1–)2–15 cm, axis ± retrorsely hairy, verticillasters 1–5, cymes (2–)6–13-flowered, 2 per node; proximal bracts lanceolate to linear, 8–38 × 1–8 mm, margins entire; peduncles and pedicels ascending to erect, glabrous or retrorsely hairy. Flowers: calyx lobes broadly ovate to obovate or elliptic, 1.7–3 × 0.9–2 mm, apex obtuse to acute or slightly cuspidate, glabrous; corolla violet to blue or purple, with faint reddish purple nectar guides, funnelform, 12–15 mm, glabrous externally, densely yellow-villous internally abaxially, tube 3–4 mm, throat gradually inflated, 3–4 mm diam., 2-ridged abaxially; stamens included or longer pair slightly exserted, pollen sacs opposite, explanate, 0.4–0.8 mm, dehiscing completely, connective splitting, sides glabrous, sutures smooth; staminode 6–8 mm, included, 0.2–0.3 mm diam., tip straight to slightly recurved, distal 2–3 mm sparsely to densely villous, hairs yellow, to 0.7 mm; style 7–9 mm. Capsules 4.5–6 × 2.5–3.5 mm, glabrous.

Phenology: Flowering Jun–Jul.
Habitat: Dry meadows, sagebrush shrublands.
Elevation: 1700–2400 m.


Penstemon laxus is known from south-central Idaho; populations are known in Blaine, Boise, and Elmore counties.

Selected References


Lower Taxa