Montana Field Guide

Large Flowered Beardtongue is a stout perennial herb with 1-2 erect stems that are 5-10 dm tall and arising from a taproot surmounted by a woody, usually unbranched crown. The spoon- to egg-shaped basal leaves are 3-16 cm long and have petioles and entire margins. The opposite, clasping stem leaves are shorter and broadly oblong. Foliage is glabrous, thickish, and covered with a thin, bluish wax. The inflorescence consists of 3-7 clusters of 2-4 short-stalked flowers in the axils of the reduced upper leaves. The tubular corolla is flared and 2-lipped at the mouth, 35-48 mm long, and pink to lavender or pale blue. The 5 broadly lance-shaped calyx segments are 7-11 mm long and usually green throughout. The 4 anthers are glabrous.

Flowering and fruiting April-July.

The combination of exceptionally large flowers and glabrous inflorescence and anthers distinguish this species from others in Penstemon. It most closely resembles P. nitidus but the latter has a corolla less than 20 mm long. A hand lens may be required for identification.

Sandy soil of valleys on the plains.

POLLINATORS
The following animal species have been reported as pollinators of this plant species or its genus where their geographic ranges overlap: Bombus vagans, Bombus appositus, Bombus auricomus, Bombus bifarius, Bombus centralis, Bombus fervidus, Bombus flavifrons, Bombus frigidus, Bombus huntii, Bombus melanopygus, Bombus mixtus, Bombus nevadensis, Bombus rufocinctus, Bombus sylvicola, Bombus occidentalis, Bombus pensylvanicus, Bombus bimaculatus, Bombus griseocollis, Bombus impatiens, Bombus insularis, Bombus suckleyi, Bombus bohemicus, and Bombus kirbiellus (Macior 1974, Thorp et al. 1983, Bauer 1983, Mayer et al. 2000, Wilson et al. 2010, Colla and Dumesh 2010, Colla et al. 2011, Koch et al. 2012, Pyke et al. 2012, Miller-Struttmann and Galen 2014, Williams et al. 2014, Tripoldi and Szalanski 2015).

STATE THREAT SCORE REASON
Threat impact not assigned because threats are not known (MTNHP Threat Assessment 2021).