Heller's Penstemon. Penstemon triflorus, Snapdragon or Figwort Family: ( Scrophulariaceae ), Heller's Penstemon. Also Called: Heller's Beardtongue, Hill Country Penstemon, Scarlet Penstemon, Penstemon triflorus subsp. triflorus. We wish to thank Wikipedia, the free encyclopedia for some of the information on this page. We share images and information with Wikipedia. An evergreen, bushy, perennial, whose pairs of dark - green, glossy, leaves occur opposite each other along the stem. Its brilliant pink to red flowers are about 2 inches long and there are darker lines inside the "throat" of the flower. The two-lipped flowers also occur in pairs. It is native to the Edwards Plateau which contains mottled yellowish clay, to clay loam surface soil; which quickly turns into rocky clay, or solid limestone rock layers, beneath the surface. Erosion has left most of the region with very shallow soils of less than 10 inches in depth. Quick Notes: Height: About 1 1/2 to 2 feet in height. The branching flower spikes can reach 2 feet tall. Flowers: The flower purple to redish flower is 1 - 2 inches in size, funnel-shaped, with short round lobes. The corolla is about 3/4 inch long, glandular and hairy on the outside. It has a broad upper corolla with a 2 - lobed lip, bent upward. The lower corolla lip is 3 - lobed and bent downward. There are 5 stamens, the fifth is sterile but bearded at the tip. Blooming Time: April - June. Stalk: Several erect, sparsely leaved stems with pinkish-lavender, bilaterally symmetrical flowers in a long, open, interrupted cluster. Leaves: Green to blue - green, fleshy, about 2 - 5 inches long, lanceolate, without stalks, smooth, those at the midstem are broadest at the base. Found: The USDA claims it is native to the USA (TX). It is found in Texas on the Edward's Plateau. Elevation: Native elevation about 100 to 3,000 feet in Texas. Hardiness: We have seen it growing in Zone 8a in Arizona. USDA Zone 8a: to -12.2 �C (10 �F) USDA Zone 8b: to -9.4 �C (15 �F) USDA Zone 9a: to -6.6 �C (20 �F) USDA Zone 9b: to -3.8 �C (25 �F) USDA Zone 10a: to -1.1 �C (30 �F) USDA Zone 10b: to 1.7 �C (35 �F) Soil pH requirements: 6.1 to 6.5 (mildly acidic) 6.6 to 7.5 (neutral) 7.6 to 7.8 (mildly alkaline) Sun Exposure: Partial Shade Full Shade Habitat: Yellowish clay, to clay loam surface soil; which quickly turns into rocky clay endemic to the Edwards Plateau in Texas. Miscellaneous: Will grow in low elevation xeriscape gardens. Flowering Photos Courtesy Of: Wikipedia, the free encyclopedia.