Penstemon davidsonii is a species of penstemon known by the common name Davidson's penstemon, honoring Dr. George Davidson. It is native to North America from the Sierra Nevada Range in California and Nevada through the Coast and Cascade ranges of Oregon and Washington into British Columbia. Penstemon davidsonii is a low, mat-forming perennial up to 10 centimetres (3. 9 in) tall. The leaves are up to 1. 5 centimetres (0. 59 in) long, thick and firm, with entire to serrulate margins. The flowers are tubular, blue-lavender to purple, and large relative to the short stature of the plant. Penstemon davidsonii is included in Penstemon subgenus Dasanthera, along with P. barrettiae, P. cardwellii, P. ellipticus, P. fruticosus, P. lyallii, P. montanus, P. newberryi, and P. rupicola. Varieties: P. davidsonii var. davidsonii - Davidson's penstemonP. davidsonii var. menziesii (D. D. Keck) Cronquist - Menzies' penstemonP. davidsonii var. praeteritus Cronquist - timberline beardtongue