Penstemon unilateralis is a tall plant reaching 24 inches at maturity with blossoms concentrated on one side of the stem, as described by the species name unilateralis. Leaves are long and narrow. The staminode, or non-functional stamen, of
P. unilateralis is white and hairless.
The flowers are born in whorls, known as “verticillasters”. Most are blue, purple, or lavender, but pink, white and even red species also occur. The petals of the flowers are joined to a corolla, having an upper and a lower lip. The upper lip has 2 lobes and the lower lip has 3 lobes. The sepals are joined to a calyx which has 5 points, sometimes with extended, linear tips.
Some species are covered with small glandular hairs on flowers or stems, but leaves are most often hairless. The shape of the leaves is usually lance-shaped or elliptic, sometimes with small teeth on the edges. Stem leaves are opposite and stalkless, sometimes clasping the stem. The fruits are capsules containing many small seeds. It’s said that the name “penstemon” was derived from the Greek “pente” meaning “five” for five stamens. There are over 250 species of penstemon; most are native to the American west.
The plant is poisonous and should not be ingested but fresh plant is ground and combined with cooking oils and beeswax to produce a salve considered to be useful for skin irritations and as a lip balm.