One of the challenges for gardeners in the northeast is finding plants that will tolerate the heavy shade of trees such as maples or conifers, and not get eaten by deer. One of the best perennials for such a situation is the genus Epimedium. Also known as barrenwort or bishop's hat, Epimediums are long-lived, easy to grow and, although they look dainty, are actually quite tough. They are best suited to shady areas of the garden in well-drained woodsy soils; although they will tolerate deep shade quite well, the best performance is generally in areas that receive a little morning sun, but are shaded in the afternoon. They can tolerate a wide range of pH, from limestone, such as found in the range of many Chinese species, to the acid soils of the northeast. They are rhizomatous and will rot in very soggy soils. Some species are clump-forming, while others are spreaders, although not invasive. They make good ground covers, especially the spreaders. The spring flowers are very delicate-looking, and come in a wide range of colors, from white to pink, red, purple, yellow and orange. The flowers, which can last 4 to 6 weeks, occur on racemes held above the foliage and many of them have long spurs, giving them a spidery appearance. They benefit from a mulch in the winter, especially as when newly planted.

The name epimedium is an ancient Greek name for a medicinal plant, described by Dioscorides, a Greek herbalist from the 1^st century AD. The root of this plant was said to cause barrenness, and the leaves to prevent conception. The Roman contemporary, Pliny the Elder, described the same plant, the leaves of which were crushed in wine and drunk in order to "restrain the breasts of virgins". The exact identity of this contraceptive plant is not clear, but in the mid 18^th century Linnaeus picked one of the likely candidates as the type species for the genus; this was Epimedium alpinum, native to Italy and the Balkans. The common name barrenwort was usually applied to this species only, but is now becoming more of a general name for any Epimedium.

The natural distribution of Epimedium species is quite broad but disjunct. It is an Old World genus with populations in eastern Asia; China and Japan; and the Mediterranean area of northern Italy, the Balkans, and east to the Caucasus, Iran and the Black Sea. A closely related genus is found in North America; this is Vancouveria found in coastal areas from Washington to northern California. The common denominator of these widely distributed regions is the presence of temperate woodlands. Where these ecological conditions prevail, Epimediums can survive. They are well adapted to conditions in northern Europe and eastern North America; the fact that they are not native in these areas is probably the result of past environmental shifts, and it is likely that these now-separated areas were parts of a vast region of temperate woodlands. The presence of a great diversity of species in eastern Asia suggests that Epimediums originated there, probably in the forest belt of the Tertiary period, between 65 and 2 million years ago. Subsequent desertification and glaciation diminished and divided this forest belt, leaving the remnants we see today.The greatest area of this remnant forest is in eastern Asia. The few species inhabiting the Caucasus and Balkans suggest that this area is also a remnant forest. There is even an isolated species in the mountains of Algeria, E. perralderianum, which apparently has resisted attempts at cultivation.

Epimediums are woodland species that spread by cylindrical, somewhat nobby, irregularly branched rhizomes just under the surface. In spring (late April to early May in western New York) flowering stems emerge from the rhizomes, generally before the new leaves emerge. At first the stems are pubescent with nodding flower buds, which rise to a height of 6 to 12" and before opening in racemes of pendulous flowers. The flowering stems can last up to 6 weeks depending on species and weather conditions. Shortly after the flowers emerge, so do the leaves. These are quite distinctive in shape and can be used to recognise the genus, although there are some variations. Generally the leaves are compound with 3 leaflets; each leaflet is ovate with a cordate (heart-shaped) base and have a margin of small spines or hairs. They range in size from 2 to 6" or greater in length. The center leaflet is usually symmetrical, while the outer pair are assymetrical, the outer basal lobe being larger than the inner lobe, somewhat resembling a bishop's mitre (hence the other common name of bishop's hat). The leaves of some species are blushed with bronze or red, especially when first emerging.

Most of the varieties currently available belong to the species Epimedium grandiflorum, which hails from Japan. Introduced by Phillip von Siebold to the Netherlands in 1830, this species caused something of a sensation, because this species sports the long spurs on the flowers which are one of the hallmarks of the genus today. Before that time the only species in gardens was E. alpinum with rather small yellow flowers. Since the 1980s several more long-spurred Asiatic species have been introduced, such as E. davidii and E. elongatum from China, and E. sempervirens from Japan, mostly thanks to the expeditions of Darrell Probst. Also, thanks to some good breeding programs, many new varieties are now available. Darrell Probst offers 184 varieties in his 2007 catalog Garden Vision, located in Hubbardston, Massachusetts.

Epimedium grandiflorum are mostly clump forming, i.e. the annual rhizome growth is very short. There are generally two growth flushes, the first when the flower stalks emerge, and the second when the foliage expands. One of the first varieties to appear in gardens was called Rose Queen, a pink flowering variety. This name has now been determined to be invalid; the proper name is 'Yubae', although no doubt 'Rose Queen' will persist in the trade. The flowers are rose-red with white spur tips. The young foliage emerges a purple bronze, later fading to green. Ultimate height is about 18". One of the best varieties of E. grandiflorum is 'Purple Prince', similar in size to 'Yubae', but with deep purple flowers. E. grandiflorum 'Red Queen' offers large rose red flowers, which tend to peek out from below large leaves. A more common red flowering variety is E. x rubrum, possibly a hybrid between E. alpinum and E. grandiflorum or E. sempervirens. This variety sports beautiful early foliage with a red flush, and small red flowers with cream spurs. Quite a vigorous grower, this is one of the spreading varieties.

Probably the most frequently encountered white flowering variety is clump-forming E. x youngianum Niveum, a hybrid between E. grandiflorum and E. diphyllum. This is a great plant for mass planting to provide a low maintenance ground cover. Ultimate height is about 12", with masses of white flowers above the green foliage. This is a bit of a slow grower, but never needs to be divided, unlike some of the yellow and orange flowering varieties. A most exquisite white variety is a relative newcomer from Japan, E. grandiflorum var. higoense 'Bandit'. This clump-forming variety sports purple-edged leaves as they emerge, and creamy white flowers, reaching about 12" in height.

Possibly the strongest spreader of all is a yellow flowering variety, E. x versicolor 'Sulphureum', one of many hybrids of E. grandiflorum and E. pinnatum produced at Ghent Botanic Garden in Belgium. This variety can produce a thick mat of foliage for good weed control, growing about 16" tall and spreading 4 or 5" a year. The young foliage is blushed red, and the pale yellow long-spurred flowers are produced on long sprays above the foliage. Another good spreader is E. x warleyense, a hybrid of E. alpinum and E. pinnatum. This variety has small orange flowers above quite dense foliage to about 12" tall, and can spread 6" a year. Both the yellow variety 'Sulphureum' and the orange 'warleyense' hold their leaves very late into the winter, and, under a snow cover, well into spring.

Epimediums are long-lived, easy care perennials, suitable for most shady situations. It is best to cut back the dead stems in early spring before the flowers stems emerge to give the plant a cleaner look. They are fully hardy to about Zone 4. They are not particularly rapid growers, except perhaps some of the spreaders, but repay the patient gardener with beautiful long-lasting flowers and almost no maintenance. They are still not common in the trade, but are well worth seeking out.