The Penstemons are the 3rd most prolific genus in North America. Also known as Beardtongues they usually have 3/4 to 2 inch long trumpet shape flowers with flaring lobes, five stamens and specifically the flower throat is flared. Flowers are in a thyrse atop the stem.
Showy Beardtongue is an erect native perennial growing 3 - 4 feet high, with a smooth unbranched stem. It is somewhat short-lived and forms a rosette the first year.
Leaves are opposite, variable, ovate to oblong, smooth edges, thick and fleshy, bluish-green waxy looking. Lower stem leaves are stalkless and upper leaves clasp the stem. Stem leaves number 4 to 8 pair. Leaves of the rosette have stalks. A new rosette of leaves forms at the base of the old flower stems in the fall and overwinters.
The inflorescence is considered to be an interrupted thyrse, that is, a branched inflorescence in which the main axis is raceme like but with lateral branches like cymes, a structure where each branch ends in a flower. The cymes are 2 to 4 flowered, with ascending branches, placed 2 per stem node and arise from opposite bracts on the stem, looking somewhat like a whorl, but actually a structure known as a 'verticillaster' and most prevalent in the Mint family. The entire inflorescence forming a cylindric shape atop the stem. All branches of the inflorescence are free of hair. The inflorescence can be from 6 to 12 inches high.
The flowers are 5-parted, up to 2 inches long, tubular with a pinkish to lavender-blue corolla that abruptly inflates just outside the calyx and ends with wide flaring lips. The upper lip has two rounded lobes and the lower lip has three. The base of the corolla is somewhat flat and this one has fine deep magenta colored veins which are nectar guides. The inside and outside of the corolla is without hair. The upper side of the corolla has a ridge. The green calyx (7-11 x 2.5-4 mm) has 5 short triangular pointed lobes. Inside, there are 5 stamens and a white style. The style, with an enlarged stigma, and four of the stamens, in pairs of different length, are appressed to the upper part of the corolla tube while the fifth degenerated stamen (a staminode) lies at the base of the tube, sticks out with its slightly hairy tip recurved to coiled. There is usually some sparse deep yellow hair around the tip of the staminode.
Seed: Fertile flowers produce a dry ovoid seed capsule, up to 20 mm long, containing numerous irregular shaped loose brown seeds. Seeds are wind distributed and the plant can self-seed. Capsules may remain overwinter on the stem. Seeds need 30 days of cold stratification to break dormancy. If stratified, plant when the ground is cool - early spring after the last hard frost or in the fall and let winter take care of the dormancy period. Seeds are large as Beardtongues go - 16,000 to the ounce.
Habitat: This is a plant of the prairies and while it can grow in semi-shade, it needs well drained soils. It grows from a woody caudex with a short taproot with fibrous secondary roots. Dark leaf spots can occur. Over-watering will cause root rot. It re-seeds itself rather easily.
Names: Penstemon is from the Greek pente, or "five," and stemon, refers to "stamen" of which there are five. The species name grandiflorus always means "large flowered". The name 'Beardtongue' refers to the hairy tip of the sterile stamen that is visible in the corolla. The author name for the plant classification, ‘Nutt.’ is for Thomas Nuttall (1786-1859) English botanist who lived and worked in America from 1808 to 1841. On his many expeditions he collected many species that had been originally collected by Lewis and Clark but lost by them. Penstemons used to be in the Figwort (Scrophulariaceae) family but contemporary Botanists have now placed the Penstemons into the family Plantaginaceae.
Comparisons: Many Penstemons tend to have hairy stems or hairy and smaller flowers, such as Foxglove Beardtongue, P. digitalis, and Pale Beardtongue where the stems and flowers are hairy, and the flowers are white and smaller with the entire plant much shorter. Both have a conical shaped inflorescence.
Above: A tall, erect example that earns the name "showy" with the cylindric shaped inflorescence. Drawing from Britton, N.L., and A. Brown. 1913. An illustrated flora of the northern United States, Canada and the British Possessions. 3 vols. Charles Scribner's Sons, New York.
Below: 1st photo - The 2 inch long tubular flower with wide flaring lips. 2nd photo - The upper opposite leaves that clasp the stem.
Below: 1st photo - The short green calyx have 5 deeply cut lobes. The flower cluster stalks rise from a pair of opposite leaf-like green bracts with only 2 to 4 flowers per cluster. 2nd photo - The 4 true stamens and the style rest against the upper part of the corolla tube while the 5th sterile stamen rests on the base of the tube (see photo above also).
Below: 1st photo - The root system has a short taproot from a woody caudex and more fibrous secondary roots. 2nd photo - The new rosette for next years growth has formed in mid-summer at the base of this years flower stems.
Below: 1st photo - Fertile flowers produce a dry brown ovoid seed capsule with the persistent calyx lobes and remnant of the style. There are 2 or 4 capsules at the leaf axil cyme - same as the number of flowers. 2nd photo - This capsule is filled with numerous irregular shaped brown seeds. Capsules will frequently remain on the stem overwinter.
Notes: Eloise Butler first noted in her log the planting of this species on May 22, 1910 - plants obtained from Borden. She planted it frequently: In 1911 and 1913 she planted more with plants obtained from Fort Snelling (Minneapolis); did three plantings in 1914; and again in '17, '18 and '20. The species name at that time was P. grandiflorum. Martha Crone also planted it frequently - 1933, '34 '35, '41, '45, '46, 48 and 250 plants in '47. It was present on Martha Crone's 1951 Garden census. Gardener Cary George planted it in 1987. Showy Beardtongue is native to Minnesota, being found in many counties in the central and western part of the State. Generally absent in the northern counties and the two tiers of southern counties. It the U.S. it is found in the remnants of the Great Plains from Ohio westward through the Rockies. It is not known in Canada.
Four Penstemons are definitely considered native to Minnesota: This species, P. grandiflorus, plus P. albidus, White Penstemon; P. gracilis, Lilac Penstemon; P. pallidus, Pale Beardtongue. Two others are: P. digitalis, Foxglove Beardtongue - once thought to be an introduction, now considered native; and P. laevigatus, Long-sepal Beardtongue - an introduction.
Eloise Butler wrote in 1911: One unfamiliar with the native flora is surprised to learn that the superb large-flowered Pentstemon is not an exotic. A hillside covered by this plant, with its large, showy, five-parted, two-lipped bells of delicate, varying shades of blue, lilac and lavender, once seen, can never be forgotten. Attached to the inner base of the corolla are five curved stamens, the origin of the scientific name, Pentstemon*. One of these stamens has, instead of the usual pollen sacs, a close tuft of hairs. This bearded stamen, partially closing up the throat of the corolla tube, and thus facilitating insect pollination, has given rise to the common name, beard-tongue. The thickish even-margined, grayish green leaves as may be noted from the accompanying print, are arranged in opposite pairs. They are covered with an evanescent bloom, like the leaves of the cabbage and pea, or the fruit of the plum. Article published on June 11, 1911 in the Minneapolis Sunday Tribune. [*NOTE: In her day the plant name was frequently spelled 'pentstemon.'
Lore: There is a minor amount of literature on native use of this plant for medicinal purposes. Moore (Ref. #30) reports that fresh parts of most penstemons can be used to make a good salve. Others report the leaves have been used for a poultice for snake bites.
References: Plant characteristics are generally from sources 1A, 32, W2, W3, W7 & W8 plus others as specifically applied. Distribution principally from W1, W2 and 28C. Planting history generally from 1, 4 & 4a. Other sources by specific reference. See Reference List for details.
Identification booklet for most of the flowering forbs and small flowering shrubs of the Eloise Butler Wildflower Garden. Details Here.
Friends of the Wild Flower Garden, Inc. Text and photos are by G. D. Bebeau unless otherwise credited. "www.friendsofthewildflowergarden.org"