Smooth Beardtongue

Penstemon glaber

Smooth Beardtongue (Penstemon glaber) is a native perennial of the plantain family, with showy blue to blue-violet tubular flowers that all face one side of the stem. It blooms in June and July, starting in late May some years, on open rocky or gravelly slopes, road cuts and grassy openings in pine forest. The 1986 plant survey of Jewel Cave lists it as Blue Penstemon, and the National Park Service also records it at Wind Cave and Devils Tower.

Free photos from other sources

Smooth Beardtongue: One-sided spike of blue-violet tubular flowers — Penstemon glaber. Jo Roberts, CC BY 4.0, resized. Get it at the source

Smooth Beardtongue: Several blue flower spikes in tall prairie grass — Penstemon glaber. Stephen Hornbeck, CC BY 4.0, resized. Get it at the source

Smooth Beardtongue: Blue flowers and green lance-shaped leaves on a limestone ledge — Penstemon glaber. Matt Berger, CC BY 4.0, resized. Get it at the source

Smooth Beardtongue: Close-up of an opened flower showing the stamens inside — Penstemon glaber. Matt Berger, CC BY 4.0, resized. Get it at the source

Smooth Beardtongue: Young plant with lance-shaped leaves and its first flower opening — Penstemon glaber. Jo Roberts, CC BY 4.0, resized. Get it at the source

Smooth Beardtongue: Dense spike of blue-violet flowers above green leaves — Penstemon glaber. Brian Dickerson, CC0 1.0. Get it at the source

Quick facts
Family	Plantaginaceae · Plantain
Status	Native perennial
Blooms	June and July, from late May some years, a few into August
Height	10–80 cm (4–31 in)
Where	Rocky slopes, limestone outcrops, road cuts and openings in pine forest
Also called	Sawsepal Penstemon, Western Smooth Beardtongue, Blue Penstemon, Smooth Penstemon
Synonym	Pentstemon glabra, Penstemon glaber var. occidentalis, Penstemon glaber var. stenosepalus, Penstemon gordonii

Roots, seeds & germination

Root: A long-lived perennial that sends up one to several stems from a single crown, unlike Large Beardtongue, which lives only a few years.

Seed: A hard, egg-shaped capsule 10–17 mm (⅜–⅝ in) long ripens in late summer and splits open at the top to release many small, angular seeds.

Germination: The seed needs a cold, moist period. In a 2015 Forest Service study of Colorado seed, 10 weeks of moist chilling at 5 °C (41 °F) raised germination two- to three-fold, while smoke had no effect. The Forest Service seed manual suggests sowing Rocky Mountain penstemons in late fall or early winter and keeping germination temperatures cool.

How do you identify Smooth Beardtongue?

Look for a dense spike of large blue to blue-violet tubes, 2.4–4.8 cm (1–1⅞ in) long, crowded to one side of the stem, smooth outside with no sticky hairs, and with reddish-purple guide lines inside the throat. The leaves are plain green, lance-shaped and attached directly to the stem without wrapping it, and the short sepals have thin, jagged edges, which gives the name Sawsepal Penstemon. Large Beardtongue has lavender-pink flowers in spaced whorls all around the stem and round, waxy blue-gray leaves that clasp the stem like shells. Narrowleaf Beardtongue has much smaller flowers in tight whorls and a golden beard inside.

When does it bloom?

June and July, from late May some years, a few into August.

Where does it grow?

Sunny, well-drained ground: rocky and gravelly slopes, limestone outcrops and ledges, road cuts, grassy meadows and openings in ponderosa pine and pine-aspen woods, mostly at about 1,500–2,050 m (4,900–6,700 ft). In the Hills it is mostly a plant of the limestone plateau and the central and northern uplands, with herbarium specimens from Lawrence, Pennington, Custer, Meade and Fall River counties and from Crook and Weston counties in Wyoming. The 1986 Jewel Cave survey lists it, the National Park Service records it at Wind Cave and Devils Tower, and Black Hills plants are the typical variety, var. glaber.