An evergreen shrub of straggling loose habit; young shoots opposite, very downy. Leaves heart-shaped, pointed, coarsely toothed, 1⁄2 to 2 in. long and about two-thirds as wide, glossy dark green, minutely downy on both sides; stalk 1⁄8 in. or less long. Flowers produced in a large terminal pyramidal panicle as much as 12 in. long and 9 in. wide. Corolla 11⁄2 in. long, scarlet, glandular-downy, with a cylindrical tube, two-lipped; upper lip hooded, the lower one decurved and divided into three linear lobes. Calyx very glandular, downy, 1⁄3 in. long, cut deeply into five lanceolate lobes; flower-stalk glandular; anthers yellow, finally whitish. Bot. Mag., t. 4497.
Native of California; discovered by David Douglas in 1831; introduced by Hartweg in 1848 through the Horticultural Society. The sterile stamen is conspicuously bearded on one side with pale hairs. Like most of the shrubby penstemons this is not very hardy, but when grown at Kew on a south wall, it makes a fine display from late June until August or even later. It is undoubtedly one of the finest of the shrubby species.
P. corymbosus Benth. – This species is allied to the preceding, but less common in gardens. It is a dwarf shrub in the wild, usually less than 11⁄2 ft high and often mat-forming. Leaves variable in shape from ovate to elliptic or oblong, up to 11⁄4 in. long and 3⁄8 in. wide, entire or finely toothed, tapered at the base, never cordate as in P. cordifolius. Flowers scarlet, borne after midsummer in terminal corymbs (not in a leafy panicle as in P. cordifolius).