Dr. Leonard Perry, Extension Professor
University of Vermont
The common name of "barrenwort" really doesn't do justice to this up and coming group of shade perennials. Unknown by many gardeners, and underutilized by most others, there are many worthy selections that have been introduced in recent years.
In previous times, this genus of perennials (Epimedium) was believed to cause "barrenness" in women, hence its common name. In more recent times, this genus has been studied for its potential use with problems of the human heart, kidneys, and bones. Another name you may see is "bishop's cap" or "bishop's mitre" because of the shape of the flowers.
These herbaceous perennial members of the barberry family have a wider range of flower colors than other of their relatives. The spring blooms come in white, yellow, rose, crimson, violet, or combinations of these on the same flower. They are generally only a half inch or less across, attached in dainty small clusters on nodding flower stems.
Barrenworts are low, generally under a foot high. Depending on selection, they either form dense mounds or gently spreading groundcovers. The leaves are shaped like hearts or arrowheads, sometimes with points or serrations along the edges. They are held on the thin but stiff, wiry stems to form dense mats above the ground. Once again, depending on selection, they may emerge before or after the flowers, or sometimes partially hide the flowers.
Leaves of some barrenworts may also emerge red or burgundy in the spring, then turn yellow or red in the fall. This is due to the red pigments (anthocyanins) which appear with cooler temperatures, and higher light. In the spring, and again in the fall, when there are few or no leaves on the trees, more light can reach these plants and so cause such coloration.
Native to rich woodlands or moist rock outcroppings, members of this genus prefer low fertility, and a slightly acidic and moist loam. Yet one of the beauties of this group is that many are quite tolerant of drought, once established. Their only main problems may be chewing from rabbits, generally early in the season on tender leaves, and chewing from insects, generally later in the season as the leaves decline. Neither problem seems to cause lasting harm to established plants.
Many new species, cultivated selections (cultivars), and hybrids are being introduced each year, partly as a result of the work and explorations of Garden Visions nursery in Massachusetts. They have introduced many new species from the wilds of China to world commerce, and have more to name and introduce. Yet barrenworts have been bred for over 150 years in Europe, and longer in Japan, to give the many cultivars and even hybrids among species which we are currently coming to know in this country.
While most of this genus originated in China, most species available to gardeners came from elsewhere. Some originally came from Europe, the Caucasus mountains, and northern Turkey (alpinum, pubigerum). Others came from the far east, to include Korea, Japan, and eastern Russia (diphyllum, grandiflorum, sempervirens). Another species came from northern Africa (pinnatum).
Cold hardiness is the main limiting factor for wider use of this genus in northern gardens; however, an increasing number are proving hardy to at least USDA zone 4 (most of Vermont for instance). Three selections in particular have proven hardy for me over some years now in zone 4 (the hybrid versicolor and its cultivar 'Versicolor', and the cultivar 'Roseum' of the hybrid youngianum). Another few years in my expanding trials will help determine more that may be quite hardy and reliable for the coldest gardens.
In a trial of 40 selections over several years at the Chicago Botanic Garden (warmer hardiness zone 5), the top three for hardiness and overall performance were the cultivars 'Crimson', 'Sonoyzki', and 'Neosulphureum'. More on these results can be found on their website (http://www.chicagobotanic.org/research/research/penotes.html), and more on the genus from the Garden Visions website (http://home.earthlink.net/~darrellpro/ ).
Return to Perry's Perennial Pages, Articles