Epimedium × rubrum, barrenwort or bishop's hat, is a garden hybrid grown for wiry, heart-shaped leaflets that emerge flushed bronze-red in spring, mature to green through summer, and often pick up red-purple tints again in fall — a quiet three-season foliage display from a plant that spreads slowly into a low, weed-suppressing carpet under trees and shrubs. In mid-spring, airy sprays of small flowers in red and pale yellow, each with distinctive backward-pointing spurs, rise on wiry stems just above or among the emerging foliage — delicate and easy to overlook individually, but effective in drifts.
It is one of the most reliably deer- and rabbit-resistant shade perennials available, rarely touched even in high-browse-pressure gardens, and it tolerates the dry shade under mature trees — where tree roots outcompete most perennials for water — better than almost anything else once established, though it appreciates consistent moisture while young. The classic barrenwort technique: shear the previous year's tattered evergreen-to-semi-evergreen foliage down to the ground in very early spring, before the new flower spikes emerge, so old leathery leaves don't hide the season's flowers. It spreads by rhizome but slowly, taking a few seasons to bulk up into a full-looking patch rather than filling in quickly.
Fungal leaf spot
Brown or purplish spots on the leaves, often ringed with a yellow halo, that spread and merge in warm, humid, or wet weather; heavily spotted leaves yellow and drop early.
Pick off spotted leaves and clear fallen debris to remove overwintering spores. Improve air circulation by thinning, and water at the base so foliage dries quickly. If it persists, apply a copper- or sulfur-based fungicide at the first sign.
Root rot
Plants wilt, yellow, and stunt even in moist soil; lower stems and roots turn brown, soft, and mushy and the plant may collapse. Most common in heavy, wet, or poorly drained ground.
Improve drainage and stop overwatering, and never plant too deep. Lift and destroy badly affected plants along with the soil around the roots. Grow in raised or free-draining beds to prevent it returning.