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Issue 20, 2003 Plant Evaluation Notes An Evaluation Report on Barrenworts for the Shade Garden Mark R. Rudy, Plant Evaluator pimedium, or barrenwort, has a long ternately compound leaves often emerge with While its natural dispersal ranges from history of both garden and herbal use. a more dissected appearance than the mature Japan across Asia into northern Africa, the E With the ability to tolerate deep shade foliage. At times, these new leaves are colorful greatest concentration of Epimedium is in and extreme drought as well as compete and may precede or follow flowering, depend- China. However, the overwhelming majority successfully with tree roots, barrenworts grow ing on the variety. Foliage with burgundy and of varieties available to the gardening public in places where other shade plants fail. Spring red accents in the spring matures to green for are species and hybrids native to places other is the peak season to enjoy them; however, the summer and then fades to yellow, red or than China. Epimedium alpinum and E. they can provide an attractive backdrop bronze in the fall. pubigerum naturally occur in Europe, the throughout the year. Due to leaf emergence An herbaceous member of the mostly Caucasus and northern Turkey; E. diphyllum, and flowering in April and May, barrenworts woody barberry family (Berberidaceae), E. grandiflorum and E. sempervirens, in Japan, are most attractive when not many other Epimedium has a wider range of flower colors Korea and Far Eastern Russia; and E. perennials are blooming in the Midwest. They than many of its relatives. White, yellow, rose, pinnatum, in northern Africa. These species complement bulb plantings and later serve as crimson and violet, as well as combinations of have been cultivated and hybridized for more an effective cover-up for declining daffodil and these on the same flower, give the gardener a than 150 years in Europe and even longer in tulip leaves. wide palette of colors for dry, shaded land- Japan, yielding not only cultivars but In addition to its garden uses, Epimedium scapes. On the nodding blooms, the outer also interspecific hybrids such as E. x rubrum, has made contributions to the world of medi- sepals attach to an arching flower stem and are E. x versicolor, E. x warleyense and E. x cine. Given the common name barrenwort, generally diminutive in comparison to the youngianum. these plants have roots that were believed to other parts. The inner sepals of most varieties Once established, barrenworts are long- cause barrenness in women. More recently, are located adjacent to the outer sepals and are lived plants that are able to stand up to the barrenworts have been studied for their the most petal-like structures of the flowers. variable stresses of the Midwest and other potential to combat disorders of the human They typically extend perpendicular to the challenging environments. Superior varieties heart, kidneys and bones. peduncle or flower stem. Furthest from the couple this toughness with a profusion of Barrenworts are low-growing, and their flower stem reside the true petals, which in blooms and excellent winter hardiness. Despite habits range from dense mounds to wide- different species have adapted into a variety its reputation as a utilitarian plant, Epimedium spreading ground covers. The often of shapes, including spurs that are contained has the pedigree to be a mainstay in any shade heart-shaped or arrowhead-shaped foliage in, or extend beyond, the colorful sepals. garden. Epimedium is also commonly called bishop’s distinguishes Epimedium from other shade- The Evaluation Project hat because the flowers resemble the miter of a lovers such as dead nettle, English ivy, The Chicago Botanic Garden (USDA clergyman. pachysandra and wild ginger. The first Hardiness Zone 5b, AHS Plant Heat Zone 5) conducted an evaluation study of 40 taxa of Epimedium from 1995 to 2001, although not all the taxa were grown for the full duration. The initial evaluation group included plants that were commercially available in 1995, with Photo: Jenny Lee subsequent additions as new varieties became available. The goal of this project was to select superior taxa of Epimedium based on winter hardiness, ornamental merit, pest and disease resistance, and cultural adaptability. Three plants of each taxon were grown in the Pullman Shade Evaluation Garden, a site that features a variety of light levels and diverse microclimates. Mature trees, including oak, maple, birch and pine, provided shade. Most plants received medium dappled shade for the entire day and were protected from wind by wood fencing around the perimeter Epimedium x versicolor ‘Neosulphureum’ 2 Plant Evaluation Notes Chicago Botanic Garden of the garden. The clay-loam soil was overall health after two years or less. Among plants to winter injury were rated fair and poor, well-drained and had an average pH of 7.5. the surviving taxa, four criteria determined the respectively. Plants that received an overall rat- Maintenance practices were kept to a overall performance rating for the plants ing are featured in Table 1. minimum to simulate home garden culture. ranging from excellent to poor. One of the most significant characteris- Overhead sprinklers provided water as needed, First, flower coverage was averaged tics that separated the best performers from the and no fertilizer was applied. Mulch consisting across all years. Considering that species of mediocre and poor performers in this trial was of shredded leaves and wood chips was placed Epimedium are seldom totally covered by winter hardiness. Generally speaking, most on the soil around the plants for water blooms even at their peak performance, 60% plant loss to winter injury occurred in the first conservation and weed suppression. and greater coverage was considered excellent two years of the trial. This was not surprising for this particular trial. Secondly, health Observations since the plants were still becoming estab- quality was summarized over the entire trial Of the 40 taxa that began this trial, 33 lished at this stage. Due to the rhizomatous period. Plant health was determined by overall Epimedium survived to receive final ratings. In order to nature of , older plants typically foliar appearance and pest and disease resis- receive a final rating, at least one of covered more area and were better able to tance throughout the growing season. When the three original plants of each taxon had to withstand winter injury. In addition to the health varied during a single year, early-season survive a minimum of three years. All plants of varieties that lost all plants in the first winter, health was given greater consideration than Epimedium x cantabrigiense, E. x several varieties lost two of three plants in the health later in the season. Thirdly, plants of E. perralchicum ‘Frohnleiten’, E. x warleyense, first two years. The poor overall ratings of each taxon were rated on overall habit quality. diphyllum E. grandiflorum E. E. x youngianum ‘Roseum’ and E. x , ‘Album’, Finally, assembled taxa were rated on winter grandiflorum E grandiflorum youngianum ‘Yenomoto’ died in the first ‘Rose Queen’, . hardiness. Plants with no injury throughout E pubigerum winter of the trial and were not retested. ‘Silver Queen’ and . were heavily the trial period were considered excellent Epimedium davidii and E. grandiflorum influenced by winter loss of plants. In while taxa that lost one or two of the three E. grandiflorum E. ‘Roseum’ were removed from the trial in poor addition, ‘Lilafee’ and Table 1: Plant Characteristics and Performance Summary Ratings Overall Epimedium Flower Color Flower Flower Spurs1 Bloom Period Height Width Rating Coverage Size 5 ★★★★ ‘Black Sea’ creamy yellow, orange 20-40% /8 in. short mid April-mid May 13 in. 24 in. 7 ★★★★★ ‘Crimson’ lavender, white highlights 40-60% /8 in. short late April-late May 13 in. 23 in. 1 ★★★★ ‘Purple Pixie’ purple, white spurs 20-40% 1 /4 in. short mid April-mid May 9 in. 12 in. 1 ★★★★ alpinum rose red, yellow spurs 40-60% /2 in. short late April-mid May 13 in. 18 in. 5 ★★★ diphyllum white <20% /8 in. none mid May-early June 7 in. 14 in. 5 ★★★ grandiflorum white <20% 1 /8 in. long late April-mid May 10 in. 24 in. 1 ★★★ grandiflorum ‘Album’ white <20% 1 /2 in. long mid April-early May 7 in. 12 in. 1 ★★★ grandiflorum ‘Lilac Sdly’ lilac purple 20-40% 1 /2 in. long mid April-mid May 10 in. 17 in. 1 ★★★ grandiflorum ‘Lilafee’ lavender <20% 1 /4 in. long early May-late May 6 in. 14 in. 1 ★★★★ grandiflorum ‘Orion’ purple 40-60% 1 /2 in. long mid April-mid May 9 in. 17 in. 5 ★★ grandiflorum ‘Rose Queen’ purple <20% /8 in. long mid April-early May 11 in. 15 in. 1 ★★★★ grandiflorum ‘Rubinkrone’ purple, white spurs <20% 1 /4 in. long late April-late May 9 in. 13 in. 1 ★★★★ grandiflorum ‘Saturn’ white 20-40% 1 /2 in. long late April-mid May 9 in. 12 in. 3 ★★★ grandiflorum ‘Silver Queen’ white <20% 1 /8 in. long late April-mid May 7 in. 14 in. 3 ★★★ grandiflorum ‘Sirius’ pale pink <20% 1 /4 in. long late April-late May 9 in. 13 in. 1 ★★★★★ grandiflorum ‘Sonoyzki’ white 40-60% 1 /4 in. long early May-late May 9 in. 14 in. 1 ★★★ grandiflorum ‘White Queen’ white <20% 1 /2 in. long late April-late May 8 in. 14 in. 1 ★★★★ grandiflorum ssp. koreanum white <20% 1 /2 in. long late April-late May 7 in. 14 in. ★★★★ higoense white <20% 1 in. long late April-late May 8 in. 13 in. 3 ★★★ pinnatum yellow <20% /4 in. short mid April-mid May 9 in. 25 in. 3 ★★★ pinnatum ssp. colchicum yellow <20% /4 in.

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