Herbs. Stems erect, (6–)10–45 cm, retrorsely hairy, also glandular-pubescent distally, not glaucous. Leaves basal and cauline, not leathery, proximals usually retrorsely hairy proximally, especially along midveins and margins, mostly glabrate distally, distals retrorsely hairy and, sometimes, sparsely glandular-pubescent, sometimes ± glaucescent; basal and proximal cauline 15–75 × (2–)5–19 mm, blade spatulate to oblanceolate or elliptic, base tapered, margins entire, apex rounded to obtuse or acute, sometimes mucronate; cauline 2–5 pairs, sessile, 11–70 × (1–)4–15 mm, blade of proximal leaves oblanceolate to lanceolate, distal leaves lanceolate, base tapered to clasping, margins entire, rarely ± denticulate distally, apex acute to acuminate. Thyrses interrupted, secund, (1–)3–24(–30) cm, axis glandular-pubescent, verticillasters (2 or)3–7, cymes 1–4-flowered, (1 or)2 per node; proximal bracts lanceolate to linear, 7–38(–60) × 1–7 mm, margins entire; peduncles and pedicels erect, glandular-pubescent. Flowers: calyx lobes lanceolate, 2.8–6 × 0.9–2 mm, glandular-pubescent; corolla blue to violet-blue, with reddish purple nectar guides, tubular to tubular-funnelform, 11–20 mm, glandular-pubescent externally, sparsely to moderately white-villous to white-lanate internally abaxially, tube 5–7 mm, throat slightly inflated, 3–6 mm diam., 2-ridged abaxially; stamens included, pollen sacs opposite, navicular, 0.8–1.2 mm, dehiscing completely, connective splitting, sides glabrous, sutures papillate; staminode 10–12 mm, included or slightly exserted, 0.3–0.4 mm diam., tip straight to slightly recurved, distal 3–6 mm densely pilose, hairs golden, to 2 mm; style 9–13 mm. Capsules 5–7 × 3–4.5 mm, glabrous. 2n = 16.
Phenology: Flowering Jun–Aug(–Oct).
Habitat: Montane meadows, ciénagas, clearings in pine and spruce-fir forests.
Elevation: 2400–3500 m.
Penstemon oliganthus is known from the Mogollon Rim (Coconino County) and White Mountains of east-central Arizona (Apache and Greenlee counties) and the Jemez and San Mateo mountains of northwestern New Mexico (McKinley, Sandoval, and Valencia counties). Crosswhite described P. pseudoparvus from five specimens from the Magdalena and San Mateo mountains in Socorro County, New Mexico, and more than 24 specimens of P. oliganthus from Arizona and New Mexico. He separated the two species based on stem indument (obscurely puberulent in P. oliganthus versus obviously puberulent in P. pseudoparvus), and flower orientation and shape (horizontal or more usually drooping and little inflated in P. oliganthus versus ascending and not inflated in P. pseudoparvus). More than 60 collections referable to these species were examined for this treatment, including the types, specimens annotated by Crosswhite, and 20 specimens from the San Mateo and Magdalena mountains in Socorro County; the two taxa appear to be indistinguishable.