What It Is
Technically, the common name for this plant is "bitterroot" (see below for an explanation), but most gardeners refer to the plant by using its genus name -- a practice I'll follow here. The full plant taxonomy is Lewisia cotyledon 'Rainbow.' Its German marketers gave it the name 'Regenbogen' (which means "rainbow"), and you may come across that cultivar name, as well, in your research. It is also sometimes sold at garden centers as 'Rainbow Mix,' because what you're buying is two or three individual plants (growing close together in one pot), each of which can flower in a different color.
Another cultivar with a name indicative of how colorful the flowers are is Lewisia cotyledon 'Sunset Strain.'
Botanists classify this succulent-like plant as an evergreen perennial. It is in the purslane family, as is the weed, common purslane and the annual popular as a bedding plant in dry areas, portulaca.
What Lewisia cotyledon 'Rainbow' Looks Like
The waxy, lanceolate leaves grow in rosettes and are leathery to the touch. While this foliage is an asset, the plant is primarily grown for its pastel flowers, which bloom in April, May, and June. By buying the 'Rainbow Mix,' you can have some combination of salmon, orange, pink, rose, and yellow flowers. Often, if you look closely at the petals, you will see that they have white stripes. Some Lewisia plants have flowers that are altogether white.
The flowers bloom in clusters atop long, fleshy stalks. From ground level to flowers, the plants stand about 8 inches tall.
Geographical Origin, Growing Requirements
Lewisia is a North American native indigenous to several western states of the U.S. and to British Columbia in Canada. Recommended planting zones are 5-8. According to Succulent-Plant.com, it prefers a soil pH that is acidic to neutral.
Locate these perennials in full sun in the North (they can profit from some shade in the South) and give them a soil that drains well (sandy or pebbly soils work well).
Take careful note of this latter point, in particular, because crown rot is a pervasive problem with Lewisia, especially in cold weather. Its susceptibility to crown rot also means it's critical to ensure that the crown sits above ground level when you install the plant in the ground. Its habitat in the wild is scree, so it thrives in poor soils and makes a good rock garden plant.
Plant Care for Lewisia cotyledon 'Rainbow'
You can further provide the drainage this perennial so craves by applying a gravel mulch around it. Some gardeners who grow the plant in a container set the pot on its side during the winter to avoid any buildup of excessive moisture around the crown. In terms of pest-control measures to take, you may have to kill slugs if you notice holes being chewed in the leaves.
After blooming, deadhead to foster further flowering. You can also propagate the plant after it has completed flowering. As with hens and chicks, propagate by separating what children call the "babies" (but what horticulturists term the "offsets") from the mother plant and transplanting them.
Although they are considered drought-tolerant perennials, it's still a good idea to provide them with water during hot weather (especially while they're flowering) if you're growing them in a sunny location.
Other Types of Lewisia
In addition to L. cotyledon, some other kinds of Lewisia are:
- L. rediviva
- L. longipetala
- L. columbiana
L. rediviva is the state flower of Montana. The indigenous peoples had both culinary and medicinal uses for it. L. longipetala ("long-petaled") was hybridized with L. cotyledon, a union that resulted in the cultivar 'Little Plum.'
Origins of the Names, Place in History
The genus, Lewisia is named after American explorer, Meriwether Lewis. Lewis and Clark encountered Lewisia rediviva (before it was named that, of course!) on the famous expedition (1803-1806) they undertook at the behest of President Thomas Jefferson and brought back specimens. Botanist, Frederick Pursh is responsible for the name. He also established the genus, Clarkia in honor of the other famous explorer in the duo, William Clark.
Jefferson, by the way, had a great interest in botany. A genus is named for him, as well: Jeffersonia. In fact, I like to think of Lewisia, Clarkia, and Jeffersonia as the all-American plant trio.
As I mentioned above, a common name for Lewisia is bitterroot (other common names are Siskiyou Lewisia and cliff maids). For, although the root of L. rediviva is edible, it is very bitter until it has been cooked thoroughly. The plant gave its name to Montana's Bitterroot Mountains, Bitterroot River, and Bitterroot Valley.
Uses in Landscaping
I grow mine in a terra cotta planter, which allows me to use it in a number of ways. But whether you grow it in the ground or in a container, here are some of the uses for Lewisia cotyledon 'Rainbow':