Penstemon cobaea

Stems retrorsely ascending to erect, (15–)25–65(–100) cm, puberulent proximally, glandular-pubescent distally. Leaves basal and cauline, sometimes basal absent or withering, ± leathery or not, glabrous or puberulent to pubescent; basal and proximal cauline petiolate, 35–120(–150) × 8–55(–76) mm, blade spatulate to oblanceolate or elliptic, base tapered, margins subentire or serrate to dentate, apex rounded to acute; cauline 4–8 pairs, sessile, 35–120(–150) × 10–45(–54) mm, blade ovate to lanceolate, base tapered to cordate-clasping, margins subentire to serrate or dentate, apex acute, rarely obtuse. Thyrses interrupted or continuous, cylindric, 10–30(–52) cm, axis densely glandular-pubescent, verticillasters 3–6(–8), cymes 2–6-flowered, 2 per node; proximal bracts ovate, 20–78 × 8–74 mm; peduncles and pedicels densely glandular-pubescent. Flowers: calyx lobes ovate to lanceolate, (8–)10–16 × 2.5–4.5 mm, densely glandular-pubescent; corolla white to pink or violet to purple, with reddish purple nectar guides, ventricose-ampliate, 35–55 mm, glandular-pubescent internally, tube 10–14 mm, throat abruptly inflated, slightly constricted at orifice, (15–)18–25 mm diam., rounded abaxially; stamens included, pollen sacs opposite, explanate, 1.3–1.6 mm, dehiscing completely, sutures smooth; staminode 23–30 mm, included or barely exserted, 0.6–0.9 mm diam., tip recurved, distal 20–25 mm sparsely to moderately villous, hairs white or golden yellow, to 3.5 mm; style 18–34 mm. Capsules 13–18 × 8–10 mm.

Distribution

United States.

Discussion

Varieties 2 (2 in the flora).

Penstemon cobaea occurs widely in the central and southern Great Plains and into the Ozark Plateau. The species is a popular ornamental used in the breeding of the European or large-flowered hybrids of Penstemon (D. Lindgren and E. Wilde 2003). A chromosome count of n = 32 (R. Piotrowska 1934) appears doubtful.

Selected References

None.

Lower Taxa

Penstemon cobaea var. cobaea, Penstemon cobaea var. purpureus

Key

1	Corollas white to pink.	Penstemon cobaea var. cobaea
1	Corollas violet to purple.	Penstemon cobaea var. purpureus