Showy penstemon is a fine perennial wildflower, consisting of one to several stems arising as much as 90 cm high. This penstemon has both basal and stem leaves. Both are typically glabrous or occasionally found with some fine hairs. The leaves are all entire margined. The basal leaves are narrowly lanceolate to elliptical in shape, and may be as much as 15 cm long. The stem leaves are smaller, linear to lanceolate, without petioles. The stem leaves may be channeled or somewhat v-shaped in cross-section.
The inflorescence is mostly long and narrow, with 4 to 12 closely spaced clusters of of flowers. The sepals are lanceolate to ovate (to 10 mm long). The corollas are violet, purplish, or bright blue in color. The corolla is also strongly two-lipped. Two deep clefts on opposite sides of the corolla separate the upper and lower lips. The tube may range in length from 25 to 38 mm.
Showy penstemon is found in varied habitats, from subalpine conditions through the ponderosa pine forests east of the Cascades to the sagebrush "desert".
Showy penstemon is a widespread species, being found from central and eastern Washington south through Oregon (east of the Cascades), west to the Siskiyou Mts. , east into southwest Idaho and Utah, and further south into southern California.