Shrubby Penstemon delivers eye-catching color

Plant taxonomy — the study of the principles and practice of classification — has been debated among botanists since 1753 when Carl Linneaus, Swedish physician, naturalist, and taxonomist, published his two-volume "Species Plantarum". Describing more than 7,300 species, it is accepted today, around the world, as the beginning of the binomial (two names) system of classifying plants used globally today.

Over the years, this system has been refined, and plants reclassified based on new discoveries, but never more than after the ability to sequence a plant's DNA. Shrubby Penstemon (Penstemon fruticosus) is one of the many plants that has found a new taxonomic home based on its DNA fingerprint.

Early classification of plants used the similarities of observable (sometimes with a magnifying glass or microscope) physical features, such as leaf shape, the number of petals in a flower, fruit type, whether it is woody stemmed or herb-like, and dozens of other characteristics. Broad groups are then broken down into more closely related groups until one arrives at “genus” and “species,” the two names making up a plant's scientific name. DNA shows botanists similarities and differences in genetic make up and is now considered more descriptive of evolutionary relationships than mere observable characteristics.

The Penstemon genus, to which Shrubby Penstemon belongs, was originally placed in the Scrophulariaceae, or Figwort family. But, due to its closer DNA resemblance, it has been moved to the Plantaginacea, or Plantain family. It will take some time for texts, both printed and online, to catch up with the change.

Like its classification, the names of many plants are also based on physical characteristics. From the Greek comes “penta” meaning “five” and “stemon” for “stamen,” the male, pollen producing part of a flower. The species name “fruticosus” means shrub-like, describing the lower stems of Shrubby Penstemon which are woody.

Collected by the Lewis and Clark expedition of 1803-1806, Shrubby Penstemon is widespread from the Rocky Mountains west to the northwestern United States and Canada. Prominent on open slopes from low-lying canyons to timberline, these lavender to light-purple, one-to-two inch-long tubular flowers create an eye-catching display of color from May to August, depending on elevation.

Shrubby Penstemon is a hardy perennial growing up to a foot high and spreading up to 18 inches. It thrives in full sun to light shade, in gritty, well-drained soil with infrequent watering. Flowers grow in loose clusters of pairs on stalks with few leaves, rising above the base foliage. They are five-petaled, joined at the base to create a tube. At the end of the tube the petals flare and separate asymmetrically into a 2-lobed upper lip and a 3-lobed lower lip, reminiscent of their cousins, snapdragons.

Inside the flower tube are five stamens. Four are pollen producing with feathery anthers. The fifth is sterile and covered with fine hairs giving rise to another of the plant's many common names, Beardtongue.

Northwest American tribes used the plant for food, fiber, as a dye and for a variety of physical ailments, though it is not widely used today for medicinal purposes.

Spreading moderately, Shrubby Penstemon shows off in rock gardens, perennial and pollinator gardens. It is a favorite with bees and butterflies, but deer tend to leave it alone.

Shrubby Penstemon grows in the dry rock habitat of the North Idaho Native Plant Arboretum, 611 S Ella Ave., Sandpoint. Pictures and a description are found in “Landscaping with Native Plants in the Idaho Panhandle,” a KNPS publication available at local bookstores and the Bonner County History Museum.

Native Plant Notes are created by the Kinnikinnick Native Plant Society. To learn more about KNPS and the North Idaho Native Plant Arboretum, visit nativeplantsociety.org.