Epimedium x perralchicum Common name: barrenwort, bishop's mitre Family: Berberidaceae Vital statistics Height and spread: Clumps up to 40cm (16in) high by 60cm (2ft) wide Form: Clump-forming rhizomatous perennial Soil: Fertile, moist soil Aspect: Partial shade Hardiness: Hardy throughout the British Isles

Massed plantings of epimediums can be found in the Wild Garden, along with many other woodland and moist shade loving plants. They help to provide interest both in the spring, with their flowers and young foliage, and in the autumn when the foliage of many species colours up well.

Wisley holds an NCCPG National Collection of Epimediums with over 80 different specimens growing throughout the gardens.

Epimedium

Epimediums are found in two main areas of the northern hemisphere, one being the Mediterranean, where four species grow in light woodland, scrub and shady, rocky places and the other being temperate east Asia. Thirty three species are named from China, four from Japan and one from Kashmir, where they grow in similar situations to the western group but require more shade and moisture.

All the species are hardy, semi-evergreen to evergreen clump-forming rhizomatous perennials retaining their leaves throughout the winter. In spring the fresh green foliage is often tinged with pink, bronze or red. In summer the leaves are deep green turning to rich tints of yellow, red and bronze in autumn.

Small saucer to cup shaped flowers are borne from spring to early summer in various colours including yellow, white, pink, red and purple.

The name Epimedium comes from epi, upon, and Media, the country of Medes, south-west of the Caspian Sea. It was first used by the Greek herbalist Dioscorides in the first century AD to describe a plant with ivy-like leaves and a black root growing in watery places.

Despite being named by a herbalist and appearing in several herbals Epimedium was not widely used in the west. The Oriental species however have been used medicinally for centuries. In modern Chinese herbalism several species are still used to treat aliments including paralysis of the legs and high blood pressure, while in Japan they are used to treat hypertension.

Epimedium x perralchicum

E. x perralchicum is a robust, evergreen hybrid with glossy deep green leaves which an attractive bronze when young. Bright yellow flowers up to 2cm (3/4in) across are produced in spring, showing above the foliage for some time before leaf growth tends to cover them up.

Named by Professor William Stearn in 1938, Epimedium x perralchicum was found growing at Wisley in a planting made some time between 1878 and 1902 by the former owner George Ferguson Wilson.

The hybrid was distinct from the surrounding plants of E. perralderianum and E. pinnatum subsp. colchicum, Stearn noticing that 'most of them agree exactly with neither E. perralderianum nor E. pinnatum subsp. colchicum, but combine in various ways their features'.

Two cultivars are common in cultivation, namely 'Frohnleiten', a german cultivar selected by Heinz Klose which has bigger flowers, and 'Wisley' a selected form of the original hybrid that is generally larger, with bigger flowers and brighter evergreen foliage.

AGM

The RHS Floral Committee A awarded Epimedium x perralchicum an Award of Garden Merit and described it as: 'Evergreen perennial to 40cm tall, forming a mat of leaves divided into 3-5 spiny-edged, ovate leaflets. Open sprays of bright yellow flowers 15mm wide.'

Cultivation

Most epimediums are tolerant of widely different conditions. All grow best in humus-rich, moist, well-drained soils, though the Japanese species are not happy on alkaline soils.

Epimedium x perralchicum is tolerant of drier soils in sun or semi-shade but will produce fewer flowers under these conditions. On moister soil it will tolerate more sun.

For the best display of foliage and flowers clip back the old leaves in late winter or early spring before the flower spikes have formed. Where frosts are prolonged or severe provide a deep winter mulch to protect the rhizomes close to the surface.

Regular mulching and feeding is recommended as the dense network of fibrous roots will in time remove soil nutrients, reducing leaf size and the number of flowers produced. Those forming tight clumps also need to be divided and replanted every three to five years to ensure good foliage and flower displays.

Vine weevils are the worst pest, attacking the roots in particular. Slugs, snails and rabbits will also browse on the young growth.

Propagation

Epimediums are best propagated by division in autumn when the new roots can establish quickly and the foliage is tougher and less prone to damage. The young leaves are brittle and easily snap off.

More information

Epimedium: molecular phylogeny