Penstemon osterhoutii

Stems ascending to erect, (6–)26–77 cm, glabrous. Leaves basal and cauline, glabrous; basal and proximal cauline 32–150 × 9–40 mm, blade oblong to ovate, base tapered, apex obtuse to acute; cauline 4–7 pairs, sessile, (11–)18–75 × (4–)10–38 mm, blade oblong to ovate, base clasping or cordate-clasping, apex obtuse to acute. Thyrses interrupted, cylindric, (4–)14–37 cm, axis glabrous, verticillasters (3–)6–10(–14), cymes (1 or)2–8-flowered; proximal bracts ovate to oblong, (6–)24–43 × (3–)16–28 mm; peduncles and pedicels glabrous. Flowers: calyx lobes ovate, 4–6.8 × 2–3 mm, margins erose, broadly scarious, glabrous; corolla blue to violet or lavender, with reddish violet nectar guides, guides passing onto limb, tubular-funnelform to ventricose, 15–18 mm, glabrous externally, sparsely to moderately white-villous internally abaxially, rarely glabrous, tube 6–8 mm, throat gradually inflated, 7–10 mm diam., rounded abaxially; stamens included or longer pair reaching orifice, pollen sacs divergent to opposite, 1.1–1.3 mm, sutures papillate; staminode 11–13 mm, reaching orifice or slightly exserted, 2–3 mm diam., tip recurved, prominently bifurcate, distal 5–7 mm densely villous, hairs yellowish or brownish yellow, to 1.5 mm; style 10–12 mm. Capsules 11–13 × 5–7 mm.

Phenology: Flowering May–Jun.
Habitat: Sandy or clayey soils, sagebrush and desert shrublands, pine-juniper woodlands.
Elevation: 1600–2700 m.

Colo.

Discussion

Populations of Penstemon osterhoutii are known from Eagle, Garfield, Grand, Pitkin, Rio Blanco, Routt, and Summit counties. The species shares some characteristics with P. pachyphyllus; it differs by larger, sky blue corollas with violet nectar guides that extend onto the corolla limbs (as in P. mucronatus) and corollas sparsely to moderately white-villous internally, rarely glabrous, on the abaxial surfaces.

Selected References

None.

Lower Taxa