Epimedium pinnatum
Common Name: bishop's hat
Type: Herbaceous perennial
Family: Berberidaceae
Native Range: Northern Iran
Zone: 5 to 8
Height: 0.50 to 1.00 feet
Spread: 0.50 to 1.00 feet
Bloom Time: April to May
Bloom Description: Yellow with red spurs
Sun: Part shade to full shade
Water: Dry to medium
Maintenance: Low
Suggested Use: Ground Cover, Naturalize
Flower: Showy
Tolerate: Rabbit, Deer, Drought, Heavy Shade, Erosion, Dry Soil, Shallow-Rocky Soil

Culture

Easily grown in average, acidic, dry to medium moisture, well-drained soils in part shade to full shade. Prefers loose, organically rich loams with consistent moisture in part shade (sun-dappled or morning sun). Foliage will usually burn in full afternoon sun. Tolerates full shade. Also tolerates drought and dry shade (rhizomes hold moisture) once established. Intolerant of alkaline soils. Clumps spread somewhat slowly by creeping rhizomes, but will form attractive colonies over time. Foliage is evergreen in warm winter climates, but foliage may drop to the ground in cold St. Louis winters. Regardless of winter performance, it is still best to cut back any remaining old foliage in late winter prior to the emergence of the new growth. Propagate by division in early spring or fall.

Noteworthy Characteristics

Epimedium pinnatum is a rhizomatous, clump-forming, evergreen perennial that grows to 8-12" tall. It is native to woodland areas of the Caucasus (subsp. pinnatum from regions near the Caspian Sea and subsp. colchicum from regions near the Black Sea). Showy flowers (to 3/4" wide) feature bright yellow petal-like inner sepals, red spurs, and minute brownish petals. Flowers bloom in spring (April-May) in terminal racemes (12-30 flowers) atop leafless flowering stems (plant leaves are all basal) rising to 12" tall. Basal leaves are biternate (9 leaflets) or pinnate (5 or 11 leaflets). Dark green leaflets (to 3" long) with red or white surface hair (maturing to hairless) have acute tips, cornate bases and serrate margins. E. pinnatum subsp. colchicum is a very popular landscape plant, and primarily differs from subsp. pinnatum by having showier flowers on larger plants (12-16" tall).

Genus name is of unclear origin and meaning but the Greeks used epimedion for a very different plant.

Specific epithet comes from the Latin word pinnatus meaning feathered in probable reference to leaf shape.

Epimediums are commonly called bishop’s hat (four-spurred flowers of some species resemble a clergyman's biretta) or barrenwort (root extract was once believed to prevent female conception).

Problems

No serious insect or disease problems. Mosaic virus (transmitted by aphids) is the main disease problem.

Garden Uses

Ground cover or edger for shady areas. Mass in woodland gardens, wild gardens or naturalized areas. Also effective in partially shaded areas of rock gardens and border fronts. Grows well under trees. Edger for paths and walkways.