Plant of the Week

Lewisia pygmaea range map.
Lewisia pygmaea range map. USDA PLANTS Database.

Lewisia pygmaea.
This very tiny plant is usually overlooked by hikers, and easily trampled. Photo by Andrew Kratz.

Lewisia pygmaea habitat.
Pygmy bitterroot occurs in the high country. Photo by Andrew Kratz.

Pygmy Bitterroot (Lewisia pygmaea)

By Andrew Kratz

The pygmy bitterroot (or alpine lewisia) is widespread at upper elevations in the western United States from Alaska to California and as far east as South Dakota. Like its larger relative, Lewisia rediviva, it was first collected for science on the Lewis and Clark Expedition in Montana in 1806. Often less than an inch tall (though typically closer to 2 inches), it is usually overlooked by hikers and other recreationists. This plant is best observed by at close quarters, and often with a magnifying glass!

The species is a member of the purslane family, and it may have originated from a cross between two other species. Its growth form is variable across the geographic range of the species. The leaves are simple and fleshy; they may be alternate, opposite, or form a basal rosette. The tiny flowers are single on a stem, and may be various shades of pink or sometimes white, often with darker pink veins. The fleshy root is carrot-shaped and edible, but the outer skin of the root is very bitter. Habitat for this plant varies from stony soils in subalpine meadows, to sparsely vegetated areas in the alpine. Soils are sandy or loamy, and range from neutral to strongly acidic.

Natural populations tend to be small and isolated. However, it is suitable for rock gardens with the right conditions, and is relatively easy to grow. Seed is available commercially.

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Pacific Mosquitofern (Azolla filiculoides).
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