Freeman, in prep (draft for FNA vol. 17), Allred and Ivey 2012, Heil et al. 2013

Duration: Perennial Nativity: Native Lifeform: Subshrub General: Subshrub, 20-60 cm tall, with 5-100 or more stems per plant; stems ascending to erect, glabrous or scabrous near the base. Leaves: Opposite and sessile along the stems; blade linear, 5-30 mm long and 1 mm wide, with a tapered base, abruptly pointed tip, and glabrous or scabrous edges. Flowers: Pale pink and showy; arranged in cylindric, interrupted panicles, 6-15 cm long, located the ends of all the branches; sepals 5 per flower, fused at the base, glabrous; corolla 14-28 mm long, salverform and weakly 2-lipped, with 5 abruptly spreading lobes, the upper 2 lobes often reflexed (curled back) and the lower 3 lobes spreading outward; corolla tube pink, with the lobes often lighter pink or nearly white, and the inner surface of the tube marked with red-purple nectar guide lines on one side. Fruits: Capsules 6-9 mm long and 3-5 mm wide, glabrous; splitting open longitudinally to release many dark brown seeds, 1-2 mm long. Ecology: Found on sand dunes or in sandy soil in desert shrubland and pinyon-juniper woodland, from 2,000-7,000 ft (610-2134 m); flowers May-September. Distribution: WY, UT, CO, KS, OK, TX, NM, AZ, NV; south to MEX. Notes: True to its name, this shrubby Penstemon is not obviously recognizable as a member of its genus. However, it has the major visible characteristics of the genus: opposite, sessile leaves; a 5-lobed, 2-lipped corolla without a sac or spur near the base of the tube; and each flower has 4 fertile stamens plus one sterile, threadlike stamen called a staminode. The 2-lipped corolla is a bit subtle in this species; look closely at the pale pink flowers and you'll see that the upper 2 petals are slightly more reflexed backward than the lower 3 petals. P. thurberi is a similar species with a more southerly distribution; it has smaller flowers, with blue-purple funnelform corollas 8-14 mm long (P. ambiguus has pink salverform corollas, 14-28 mm long). Var. ambiguus has scabrous lower stems and leaf margins. Var. laevissimus has glabrous stems, and leaf margins that can be glabrous or scabrous. Ethnobotany: Infusion of plant used as an emetic; plant used for spider bites or poultice of plant applied to eagle bites; also used as a fumigant for livestock with snakebites. Hopi noted when the flowers begin to appear to indicate when the season for watermelon planting was over. Etymology: Penstemon comes from the Latin paene, nearly or almost, and Greek stemon, thread, alluding to the single sterile stamen within each flower; ambiguus likely alludes to the flowers, which lack the characteristic 2-lipped look of most Penstemon spp. Synonyms: Leiostemon ambiguus Editor: AHazelton 2017