Lewisia rediviva (bitterroot)
Bitterroot was first described as new to science in 1813 from specimens collected during one of the first western expeditions across the United States to the Pacific coast, but the species was already well-known and used by local Native Americans.
About this species
Bitterroot is a small plant with white to purplish pink flowers. The species name, rediviva, means ‘brought back to life’ and refers to this plant's ability to sprout new growth, even after long periods of drought.
The genus name, Lewisia, commemorates Captain Meriweather Lewis, one of the leaders of the famous Lewis and Clark Expedition that crossed the Rocky Mountains to reach the west coast of the USA (1804-1806). The plants discovered by Lewis and Clark were already well-known to Native Americans in the area, and eaten by local people. Today, bitterroot is the state flower of Montana and has given its name to the Bitterroot Range, which runs north-south and forms the divide between Idaho and Montana.
Geography & Distribution
Occurs in the western United States and Canada, from southern California to British Columbia and east into Wyoming and Colorado.
The habitat of Lewisia rediviva has a dry climate, with a long cool growing season, with most of the annual precipitation often falling as snow.
Lewisia rediviva (Image: Richard Wilford)
Bitterroot is a low-growing perennial with succulent, fleshy leaves, up to 5 cm long but only 2–3 mm wide. The plant dies down for the dry summer. The leaves are held in a rosette and are either evergreen or die back to the thick fleshy roots.
The solitary, silky flowers, are up to 7.5 cm wide, and held on short stems. They are composed of 4–9 papery sepals and 12–20 petals surrounding a bunch of stamens. The flowers can be white, but shades of rose or purplish pink are more common. They open in late spring and, after withering, become detached and blow along the ground, dispersing their seeds.
There are two varieties: Lewisia rediviva var. minor and L. rediviva var. rediviva. The former occurs in the mountains of Nevada and southern California and is distinguished by its smaller flowers.
Threats & Conservation
The conservation status of bitterroot is classified as ‘Secure’ (G5) according to the NatureServe Conservation Status Ranks.
The common name bitterroot refers to the taste of the roots, which are cooked and eaten by Native Americans. The species is also used by several Native American groups as a medicinal plant for sore throats, heart and pleurisy pain, and to increase milk flow after childbirth.
Lewisia rediviva is cultivated as an ornamental.
An extraordinary observation
A remarkable story is told by Sir William Hooker in Curtis’s Botanical Magazine: ‘The specimen from which our figure was taken at Kew… when gathered with a view of being preserved for the Herbarium... was immersed in boiling water on account of its well-known tenacity of life. More than a year and a half after, it notwithstanding showed symptoms of vitality and produced its beautiful flowers in great perfection in May of the present year  in the Royal Gardens of Kew.’
This species at Kew
Bitterroot can be seen growing in the Davies Alpine House at Kew.
Spirit-preserved specimens of Lewisia rediviva are held in Kew’s Herbarium, where they are made available to researchers, by appointment. The details of some of these specimens can be seen on-line in the Herbarium Catalogue. Roots of Lewisia rediviva are held in Kew’s Economic Botany Collection, where they are available to researchers, by appointment.
Millennium Seed Bank: Seed storage
Kew's Millennium Seed Bank Partnership aims to save plant life world wide, focusing on plants under threat and those of most use in the future. Seeds are dried, packaged and stored at a sub-zero temperature in our seed bank vault.
Description of seeds: Average 1,000 seed weight = 2.28 g.
Number of seed collections stored in the Millennium Seed Bank: One.
Germination testing: 55% germination was achieved on a 1% agar medium, at 5°C, on a cycle of 8 hours daylight/16 hours darkness.
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