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A creeping, mat-forming shrub with erect flowering stems 2 to 6 in. high, downy. Leaves on the prostrate stems rather thick, glabrous, not glaucous, 3⁄16 to 3⁄8 in. long, variable in shape from elliptic to obovate or roundish, entire or more or less saw-toothed, usually obtuse to rounded at the apex, shortly stalked; the leaves on the flowering stems below the flowers reduced in size and often bract-like. Racemes glandular-downy, few-flowered. Calyx 5⁄16 to 7⁄16 in. long, the sepals lanceolate to ovate-lanceolate. Corolla lavender- to violet-coloured, 1 to 11⁄2 in. long, between tubular and funnel-shaped, two-lipped, the upper lip two-lobed, the lower one three-lobed and hairy near the base. Anthers densely bearded; staminode much shorter than the fertile stamens, hairy at the tip.
Native of western N. America from the southern end of the Sierra Nevada, California, north to southern British Columbia (including the southern part of Vancouver Island); it also occurs in Alaska and extends east into Nevada. It was discovered by Menzies during the Vancouver expedition 1790–5 and described by the elder Hooker under the illegitimate and confused name P. menziesii (on this name see further below). The specimen was said to have been collected in Nootka Sound (on the Pacific coast of Vancouver Island), where the species is still to be found. But J. C. Bennett has pointed out that these sea-level plants are robuster and larger-leaved than the plant found by Menzies, which matches those that occur high in the mountains of Vancouver Island. Yet Menzies cannot have visited these high-level locations, which would in his time have been inaccessible owing to the dense forests and the hostility of the Indians (Journ. R.H.S., Vol. 59 (1934), p. 353). A possible explanation is that at the end of the 18th century the small-leaved very dwarf form still existed at sea-level as a relict from a cold and wet climatic phase of the post-glacial epoch, but has since disappeared.
P. davidsonii was described in 1892 from a plant collected in the Yosemite region of California. In this plant the leaves are quite entire, as they are on all plants from California, while in the type of P. menziesii they are toothed. Judging from the plants in the Kew Herbarium the presence or absence of teeth is not correlated with any other character, but the combination P. davidsonii var. menziesii (Keck) Cronquist is perfectly valid, and could if necessary be used to distinguish plants with toothed leaves from those with entire leaves.
The name P. menziesii appeared in garden literature around the middle of the last century, and the name P. davidsonii early in the present century. Yet curiously enough the species to which these names properly belong did not come into cultivation until the 1930s. This introduction was at first known as P. menziesii microphyllus and is believed to have come from the Selkirk mountains of British Columbia. This is a high-mountain form, growing only an inch or two high, with leaves 3⁄8 in. or less long with scarcely noticeable toothing, of a dark, glossy green. The flowers, borne May and June, are of a remarkable size for such a small-leaved plant.
For the plant distributed by the Six Hills nursery as P. davidsonii, see P. rupicola, treated under P. newberryi. The plant known to Farrer as P. davidsonii was probably a form or hybrid of P. newberryi. It had stems that ended ‘in baggy bugles of a ferocious aniline red-mauve most terrible and breath-taking to look upon in the sun’ (The English Rock Garden, Vol. 2, p. 49).
Note. Although Hooker’s description of P. menziesii is based on the Menzies specimen from Nootka, he cited as a synonym Gerardia fruticosa Pursh, which is the type of Penstemon fruticosus (Pursh) Greene. This citation renders the name P. menziesii illegitimate, for if Hooker considered the Menzies specimen to belong to the same species as the penstemon which Pursh named Gerardia fruticosa, then he should have used the epithet fruticosus. This may seem a pettifogging reason for suppressing a long-established name, but there is the further consideration that Hooker’s P. menziesii is a confused species, in effect compounded of two distinct species, namely P. davidsonii and P. fruticosus. This in part explains how P. menziesii came to be used in such a wide sense.