About Penstemon cobaea Nutt.
Penstemon cobaea Nutt. typically grows between 25 and 65 centimeters (10 and 26 inches) tall, though it may occasionally reach as short as 15 cm (6 in) or as tall as 100 cm (3.3 ft). Stems grow upright, or curve backward before growing upward. The lower portions of stems are puberulent, covered in very small, fine hairs, while upper stems are glandular-pubescent, covered in glandular hairs. This species produces both cauline leaves (attached to stems) and basal leaves (growing directly from the plant base); however, basal leaves are sometimes absent or wither by the time flowering begins. Leaves are dark green and quite large. Basal leaves and the lowest cauline leaves measure 3.5 to 15 centimeters long (usually shorter than 12 cm) and 0.8 to 7.6 cm wide (usually narrower than 5.5 cm). Their shape ranges from spatulate to oblanceolate or elliptic, with a tapering base, and edges may be nearly fully smooth, bear forward-facing asymmetrical teeth, or bear regular teeth. Each stem holds four to eight pairs of oppositely attached leaves; lower leaves have petioles, while upper leaves attach directly to stems by their bases. Among Penstemon species native to the United States, Cobaea penstemon produces the largest flowers. The inflorescence usually holds 3 to 6 groups of flowers, and occasionally as many as eight. Each paired cyme in a group holds 2 to 6 flowers. Individual flowers measure 3.5 to 5.5 centimeters (1.5 to 2 inches) long, with five lobes: two large lobes on the upper side and three small lobes on the lower side. Flowers have an internal structure reminiscent of a ribcage, and their color ranges from white to dark pink, marked with magenta lines. In the southern portion of its native range, blooming occurs as early as April and as late as May; in the northern portion, blooming can start as early as May and end as late as June. Cobaea beardtongue is native to the plains of the United States, ranging from Texas north to Nebraska, and east to Arkansas and Iowa. In Texas, it grows mainly in the central part of the state, from Victoria northward into Oklahoma. Within Oklahoma, it grows across most of the larger eastern side of the state, and is not found in the Oklahoma panhandle. It grows in the eastern two-thirds of Kansas, and only in the far southeastern corner of Nebraska. In Missouri, most of its native range lies in the south, bordering the main population in Arkansas. Its exact location within Iowa has not been recorded. It also grows in Colorado, New Mexico, Arizona, Illinois, and Ohio, where Plants of the World Online lists it as an introduced species. Penstemon cobaea grows on hillsides, in gravel, on rocky outcrops, in gypsum soils, and in eroded pastures. After flowering, the blooms of Penstemon cobaea develop into brown and black seed capsules that hold the plant's seeds. When planted from seed, plants take approximately two years to produce flowers. For garden cultivation, plants should be spaced 40 to 50 cm (16 to 20 in) apart, and lime is often required in the soil.
