Penstemon ambiguus
Penstemon ambiguus, commonly known as the bush penstemon, pink plains penstemon, or gilia beardtongue, is a perennial wildflower of the western United States and northern Mexico. It grows in shortgrass prairies and deserts, in sandy, loose soils often with creosote or sagebrush nearby, and is famous for its spectacular pink to white flowering displays that can light up hillsides.
Description: It forms a bushy, partly woody plant with stems 20–60 cm tall. Leaves are small, narrow, and tapering. Roots stay mostly near the soil surface, though some can reach deeper.
Flowers: It mostly blooms from late May to late August. The flowers are arranged on a flowering stalk in groups of 1–3. Petals are pastel pink, sometimes milky pink or milky white on the outside; the interior has fine hairs and reddish-purple nectar guides. Each flower is 16–22 mm long, with a tube about 3–4 mm wide. The staminode (the “fuzzy tongue”) is 7–9 mm long, and the flowers are fragrant. Seed capsules are four-valved, teardrop-shaped, 6–9 mm long.
Taxonomy and varieties: Penstemon ambiguus was named by John Torrey in 1827. The species has two recognized varieties: var. ambiguus (the autonym) and var. laevissimus. Var. foliosus is an older name no longer accepted. Var. ambiguus is more northerly, found in dunes and sandy plains in parts of Colorado, Kansas, Oklahoma, New Mexico, and Texas (with some sources noting Nebraska). Var. laevissimus is more southerly, found in creosote and sagebrush landscapes and juniper woodlands in Nevada, Utah, Arizona, New Mexico, Texas, and sometimes Colorado and Wyoming; some sources also list Chihuahua, Mexico.
Pollinators and gardening: The main pollinators are small pollen-collecting bees; flies in the genus Oligodranes also visit. There is little to no nectar reward, so bees are the key visitors. Gardeners prize its showy, long-lasting blooms and hot, dry, well-drained soil needs. In warmer areas (USDA zone 9 and above) it stays green and may bloom through winter; in colder areas it dies back near ground level and is hardy to about -23 to -17 C (zone 6). Seeds germinate readily and are not significantly affected by planting at 21 C, nor by a three-month cold period at 4.5 C.
Conservation status: Apparently Secure.
This page was last edited on 3 February 2026, at 08:21 (CET).