by Bruce Brethauer
The Lewisias are succulent members of the Purslane family (which also includes Talinium, Anacampseros, Phemeranthus, the "Moss Rose", the wildflower "Spring Beauty" and many others). Approximately 20 species are recognized - all are native to the northwestern United States and southwestern Canada. The species inhabit a variety of habitats, but most of them grow in rocky outcrops, or upland plains at higher elevations, and grow best when provided with sharply drained soils, good exposure to sunlight, and moderately fertile, humus-rich soil. All species produce rosettes of lax succulent leaves, and fleshy rootstocks. The shape of the leaves are highly variable, and may differ markedly from one species to another. The rootstocks are considered edible, although they are quite bitter, and may require special processing to reduce their bitter flavor. The roots of these plants have factored in the diets and medicine of the native peoples of this region, and many of the species are known by the common name of "Bitterroot". There is a huge range of variation in the flowers of the various species, with colors ranging from white, yellow, pink, magenta, purple, and orange, with flower sizes running from perhaps as little as 1/4 inch across to nearly 2 inches wide, and petal counts ranging from 5 to as many as 19. Meriwether Lewis (of the Lewis and Clark Expedition) first collected the plant which would later be given the name Lewisia rediviva in 1805. "Bitterroot" served as an emergency food for members of the Expedition, and the genus was later named Lewisia to honor Meriwether Lewis.
The Lewisias have long been known and grown by alpine and rock gardeners, and a number of excellent hybrids and select cultivars have been been introduced over the years, yet this genus remains largely unknown outside of these circles, and plants of lewisia are very uncommon in the mainstream nurseries. Occasionally one of the "Big Box" nurseries will carry a few plants in a larger selection of mixed perennials. I had grown a plant of Lewisia "Little Plum" some years ago from a small selection of rock garden plants at a local nursery, but very recently, I had the good fortune to locate a number of quart sized pots of this plant at my local Home Depot; I couldn't resist. Lewisia "Little Plum" is an exceptional plant with especially showy flowers on compact rosettes of fleshy lance-shaped foliage. The flowers are smallish measuring to about 1.5 inches to nearly 2 inches across, and are brightly colored in pinks with deeper magenta veins; many newly opened flowers also show apricot tones in their petals - these typically fade to pink as the flowers age. The effect is so striking that plants in full bloom can attract a lot of attention. A succession of flowers are produced in early to mid spring: there are rumors that this plant may produce additional flowers intermittently through the season, but this does not reflect my experience with this plant. I would hazard that "Little Plum" is a hybrid of one of the evergreen species (most likely L. cotyledon), and one of the deciduous species, as this plants shows a tendency to loose at least some of its foliage during the heat of summer (about half of the lewisia species are deciduous, loosing their leaves in the summer and going dormant after flowering: these species typically do best in full sun, while the species which are considered "evergreen" are better grown in partial shade).
While many growers insist that the Lewisias are reasonably easy to grow, I am of a slightly different opinion - these plants do not thrive in all situations, and may not be generally suited for all gardens (or for that matter, for most gardeners). "Little Plum" requires sharp drainage, and a soil that has been enriched with organic material - well rotted leaf compost is best, but some Moo Nure worked into the soil may work well enough in a pinch. It requires good light in the morning and into the afternoon, but should be shaded during the hottest part of the day. Most of the Lewisia species grow in regions with an extended summer drought, and these frequently go dormant during the summer months. At this time most plants will loose at least a portion of their leaves, and will have a generally poor appearance. Most gardeners would interpret this incorrectly, and would try to revive the plant by giving it extra water at this time - which could possibly result in root rot and the loss of the plant. If a Lewisia is showing signs of dormancy in the summer, DO NOT give it any extra water, allow it to remain dry. In my past experience with "Little Plum", it broke dormancy in late summer or early fall as the days become cooler. At this time, it may produce a few new leaves before temperatures become too cold for any additional growth. It is my belief that the Lewisias are best grown in regions with cool summer nights, and are really better suited to higher elevations, or gardens further north, where summer temperatures can be a bit milder. Subjected to unmitigated summer heat, even the evergreen species will tend to become dormant, loosing a majority of their leaves. It may also be a good idea to protect this plant from excessively wet winter conditions by covering the plant and its surrounding bed with plastic.
Lewisia "Little Plum" is one of the gems of the greater Purslane family. Its compact size and exceptional flowers has made it a popular rock garden plant - its smaller size making it suitable for container gardens (including hypertufa troughs). Those of us who are already growing some of the winter hardy cacti, Delospermas, Phemeranthus, and other hardy succulents may already have a suitable place to plant "Little Plum". Other growers may need to prepare a site with improved drainage, and properly sited to provide the morning and early afternoon sun favored by this plant. Admittedly, this is not a plant for the average gardener; it requires a bit more attention to detail than the average gardener would be willing to provide, and even under then, success cannot be guaranteed. But for those growers who are looking for a charming accent for the front of the bed, and who do not intimidated by a plant which may be just a bit on the finicky side, "Little Plum" would be an excellent choice.