Penstemon osterhoutii

Pennell

Contr. U.S. Natl. Herb. 20: 358. 1920.

Common names: Osterhout’s beardtongue
Endemic
Treatment appears in FNA Volume 17. Treatment on page 122. Mentioned on page 111, 119, 121, 123.

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.

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

None.