Home | Next | Previous | Index | Purchase book

Idaho Mountain Wildflowers

Figwort (Snapdragon) family, Scrophulariaceae (continued)

Penstemon spp.: The penstemons (or beardtongues) are among the most beautiful of our wildflowers. Their five petaled flowers have two paired stamens. There is always a fifth sterile stamen (a “staminode”) without an anther at its tip. It may be hairy and partially occlude the floral throat of the flower, hence the common name “beard-tongue.” The flowers are born in whorls, known as “verticillasters ” (seen clearly in  the illustrations). Most are blue, purple, or lavender, but pink, white and even red species also occur. Because there are many similar species, they may be difficult to identify. 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; in the Northwest alone, there are 80 or so species. Some of the species that grow in our mountains are shown here. Although listed under Scrophulariaceae, taxonomists now believe that they should be in the plantain family (Plantaginaceae).

Plantaginaceae (Plantain family)

Shrubby penstemon, Penstemon fruticosus  (Pursh) Greene (left, right) The shrubby penstemon is an attractive, and common species that grows from mid–elevations into the subalpine zone. Its stems are woody, and its leathery leaves are evergreen. When mature, the plants form shrubs that may grow to be quite large (left). Showy, light-purple flowers are up to two inches long. Several varieties are recognized, identified mostly by the form of the leaves. Ours, illustrated here, with lanceolate, smooth-edged leaves is var. fruticosus, the most common variety. Lewis and Clark found the shrubby penstemon while on the Lolo Trail (June 15, 1806).

Mountain penstemon, Penstemon montanus Greene var. montanus (left, right) is another woody species It is usually seen growing near treeline or higher. Like the shrubby penstemon, it forms well demarcated shrubby clumps. Large violet flowers, woody stems, toothed leaves, and the high elevation at which it grows, serve to identify the plant. A related variety, Penstemon montanus var. idahoensis (D. D. Keck) Cronquist, with mostly smooth-edged leaves, grows only in Idaho.

Taperleaf penstemon, Penstemon attenuatus Douglas ex Lindl. (left; also “sulphur penstemon” for the color of one of its several varieties) is common in our mountains, often present in large patches. It is characterized by its discrete, crowded flower clusters (“verticillasters”) and is sometimes confused with Penstemon rydbergii A. Nelson, a similar plant with well defined flower clusters that grows at lower elevations.

Hot-rock penstemon, Penstemon deustus Douglas ex Lindl. (right) grows mostly on cliffs and other rocky surfaces. That growth preference, as well as its white flowers and shallowly serrated leaves, serves to identify the plant.

Payette Penstemon, Penstemon payettensis Nelson & J. F. MacBride (left), first collected in the Payette National Forest, is a central Idaho plant extending to western Oregon. It favors open sagebrush slopes, and grows high in the mountains. The plant stands out because it is tall, to two feet or more, and has large, deep blue, showy flowers. Identification of the various penstemons can be difficult as it is based both on the morphology of the plant, and on the configuration of the anthers and their four pollen sacs--visible in this illustration, although best seen with magnification and dissection of the flowers.

Dark blue penstemon, Penstemon cyaneus Pennell (right) is a similar, colorful, large-flowered plant that grows only in Idaho, Montana and Wyoming. A tendency for its flowers to be borne along one side of the stem distinguishes it from the Payette penstemon

Pale yellow penstemon, Penstemon confertus, Douglas ex Lindl. (left) is found in the northern half of Idaho. Its pale yellowish-white (“ochroleucous”) flowers distinguish the plant, as do purple anther sacs and “bearded” stamen. The name confertus means “crowded,” presumably for the flower clusters, although they are no more crowded than those of many other species.

Small-flowered penstemon, Penstemon procerus Douglas ex Graham (right) is the most common of Idaho’s penstemons. It has small, narrow-tubed, densely arrayed flowers with lips that often close the mouth of the flower. The plants are common throughout the West, from foothills to above tree-line.

“Pink Penstemon,” Penstemon confertus x procerus? The many species of penstemon, their variability, and a tendency for species to cross-breed, gives credence to the belief that the genus Penstemon is one that is actively evolving. The “pink penstemon” shown here is an example.  It appears to be a hybrid between the two species shown above, Penstemon confertus and Penstemon procerus (see Strickler, D.: Northwest Penstemons)

Wilcox’s penstemon, Penstemon wilcoxii Rydb. (left) grows in the northern half of Idaho, spilling over into neighboring states. The plants are tall, with finely serrated, large stem leaves, and a series of long paired stemlets that help to identify the plant. These bear clusters (“panicles”) of moderately large, blue flowers. The plant was collected by Meriwether Lewis near Kamiah, Idaho, in 1806.

Two penstemons with similar, large, light purple flowers are:

Fuzzy-tongue penstemon, Penstemon eriantherus Pursh (left) bears a few large, wide, light purple flowers with more-or-less prominent “guide-lines” within the throat. While eriantherus means “hairy-anther,” the degree of hairiness, and the prominence of the guide-lines varies considerably among the five recognized varieties. The Idaho variety, var. redactus Pennell & D. D. Keck, is a low plant with a rather sparsely bearded yellow stamen.

Twinleaf penstemon, Penstemon diphyllus Rydb. (right). The twin-leaved (diphyllus) penstemon is characterized by large pale-purple flowers whose upper lips are split for more than half their length, and by paired, toothed leaves ranged along the stem. A mountain plant, it grows in southern Idaho, as well as in Washington and Montana.

Globe penstemon, Penstemon globosus (Piper) Pennell & Keck (left). The globe penstemon is found in central and northern Idaho and in adjacent parts of Oregon. It is characterized by its opposing broad-based, stemless, lanceolate leaves. The species name, globosa, means "spherical" apparently referring to the obvious spherical shape of the top cluster of  flowers. (The white flowers in the images are yarrow, Achillea millefolium.)

Tweedy’s snowlover, Chionophila tweedyi (Canby & Rose) L.F. Hend. (left, right) appears soon after the snowmelt. Half a dozen or so lavender-tinged flowers, their lips turned up at the end, bloom on one side of a stem that arises from a basal rosette of small oval leaves. The plant is related to the penstemons, and was formerly classified as Penstemon tweedyi. Although occasionally seen lower, it mostly grows high in the mountains of Idaho and neighboring Montana. The name honors Frank Tweedy (1854-1937), a topographical engineer with the U.S. Geological Survey. Chionophila is from the Greek xioni meaning “snow” and filos for “friend.” The inelegant name “toothbrush flower” has also been applied to the plant.

Home | Next | Previous | Index | Purchase book