Subshrubs. Stems glabrous, glabrate, or scabrous proximally, not glaucous. Leaves cauline, opposite, not leathery, glabrous or scabrous, not glaucous; cauline sessile, blade linear, margins entire. Thyrses interrupted, cylindric to conic, axis glabrous or scabrous, cymes 2 per node; peduncles and pedicels spreading or ascending. Flowers: calyx lobes: margins entire or erose, broadly scarious, glabrous; corolla pink or lavender to violet, bilaterally symmetric, bilabiate, not personate, salverform or funnelform, glabrous externally, glandular-pubescent internally abaxially, throat slightly inflated, not constricted at orifice, rounded abaxially; stamens included or longer pair reaching orifice or barely exserted, filaments glabrous, pollen sacs divergent, explanate, dehiscing completely, connective splitting, sides glabrous, sutures smooth; staminode included, terete or slightly flattened distally, 0.1 mm diam., tip straight, glabrous; style glabrous. Capsules glabrous. Seeds dark brown to reddish brown, angled, 1–2.8 mm.

Distribution

w United States, n Mexico.

Discussion

Species 2 (2 in the flora).

Section Ambigui includes two subshrubby species of the southwestern and south-central United States and northern Mexico.

Selected References

None.

Lower Taxa

Penstemon ambiguus, Penstemon thurberi

Key

1	Corollas salverform, (14–)16–22(–28) mm.	Penstemon ambiguus
1	Corollas funnelform, 8–14 mm.	Penstemon thurberi