Shrubby Penstemon – Penstemon fruticosus var. scouleri – low, woody, fine-leaved foliage clumps covered with large, tubular, light purple blooms are locally abundant throughout the Cariboo-Chilcotin on rocky cliffs and steep, gravelly, roadside cutbanks in mid-spring. This photo was taken near Soda Creek, B.C., May 23, 2010.
Perennial. Zone 1/2. Scrophulariacea. North America; in Canada throughout the southern third of B.C. east of the Cascades and west to the Rockies, and in the United States common in Washington, Oregon, Idaho, Montana and Wyoming. A.k.a. Shrubby Beardtongue, Scouler’s Penstemon.
In bloom from May until July, depending on elevation, this floriferous sub-shrub is unmistakeable when seen on the roadside. It favours steep rock bluffs, gravel pits and roadsides, flourishing best in well-drained, rocky/sandy soil. Its pale purple blooms range in shade of warm violet to cool mauve, with occasional (very rare) white sports.
Here is what Lewis J. Clark had to say in his 1972 Wild Flowers of British Columbia:
This subshrubby species is described by its name, fruticosus meaning shrub-like. It is a variable species, but in all its forms is very beautiful. Choice forms are easily obtained for the garden by taking short cuttings, which root very readily in sand…To keep the plants attractively compact and floriferous, they should be given gritty soil with very little food.
The plants are semi-evergreen, a proportion of the leaves usually turning reddish in the fall, and later dropping. Commonly the compact framework of branches is 6-12 inches tall. Leaves are generally without hairs, up to 2 inches long, but usually shorter…narrow, almost elliptic and obscurely toothed. Flowers are relatively large (up to 2 inches long), generally blue-lavender, but so highly variable that the gardener should always be on the alert for exceptionally good colour forms. White, and beautiful pink specimens are seen occasionally…
This close-up of one of the Penstemon fruticosus var. scouleri clumps found growing in generous abundance on the gravel roadsides opposite the huge open-pit Highland Valley Copper Mine east of Ashcroft, B.C. shows the reason for the common name of this genus – ‘Beardtongue’. Lewis J. Clark: “The lower lip of the corolla is ornamented with two deep folds and with long white hairs. When the corolla is slit lengthwise, the anthers (and also the filament of the half-length infertile stamen) are seen to be densely white haired.” (Click on the image to open an enlargement, which will show the afore-mentioned long white hairs on the lip folds.)
According to Plants of Southern Interior British Columbia (Parish, Coupé, Lloyd – Lone Pine Publishing – 1996), traditional First Nations’ uses of this plant included the production of a dye to colour basket-making materials, in pit cooking to flavour root vegetables, and medicinally as a purgative, and to bathe sore eyes and sooth ulcers, wounds, and arthritic joints.
Though in general removing plants from the wild to the garden is frowned upon, in the case of this penstemon all of my guidebooks mention how easy it is to establish from stem cuttings rooted in grit or sand, and as this technique will not harm the parent plant, one may in good conscience give it a try. Seeds are abundantly produced in pointed capsules, but are difficult to germinate, so might not be the best way to obtain this lovely species.
This is definitely a plant for a specialized location, requiring full sun and extremely well-drained soil to thrive, as evidenced by its flourishing in pure gravel in the wild. It would be wonderful in a rockery where it could cascade over a border or down a slope. Bloom time is relatively short, a few weeks in late May and early June, but the plants stay reasonably attractive throughout the rest of the growing season. A good xeriscape plant.
Shrubby Penstemon and its many fellow species are much favoured by bees and hummingbirds, another point in favour of stopping to observe this plant in the wild, and of incorporating it in the garden if one has a favourable spot.
Growing in a roadside gravel pit, Highland Valley Copper Mine, Ashcroft, B.C. – June 8, 2014. A few miles west, the roadside display was even more spectacular – a veritable carpet of purple under the pine trees on both sides of the road.
Plant habit is that of a tidy round mound. Closer investigation shows that the shrubby stems radiate from a central point, with a main taproot providing the anchoring point. Highland Valley Copper Mine, June 8, 2014.
A brighter violet individual. The bloom time of Shrubby Penstemon coincides with that of the showy cream-coloured locoweed (Oxytropis sp.), making for an attractive colour combination which could be easily replicated in the rock garden.
One of the nicest displays of Penstemon fruticosus var. scouleri that I’ve ever seen is on a steep roadside cutbank above Dunlevy Ranch in Soda Creek, B.C., a few miles south of Hill Farm. This photo was taken May 23, 2010.
