Epimedium grandiflorum Seeds | Bishop’s Hat
LATIN NAME: Epimedium grandiflorum
COMMON NAME: Bishop’s Hat
Plant Profile
Bishop’s hat is a woodland perennial that spends most of the year as a low, neat mound of heart-shaped leaves and then, for three weeks in spring, produces flowers that look like nothing else in the shade border. The blooms are up to four centimetres across, with four long, curved spurs and four inner sepals that fold back, coloured in white, pale pink or violet, and they hang in loose sprays above the foliage on wiry stems. The leaves are bronze when they open, turn green, and often colour again in autumn. It comes from the mountains of Japan, where it grows in light woodland on humus-rich, moist but drained soil, and it spreads slowly by rhizome into a dense, weed-proof mat. Height is 30 to 45 cm; spread is patient but steady.
Science & Biotechnology
Epimedium has a seed dispersal system worth knowing about, because it governs how the plant is propagated. Each seed carries a fleshy elaiosome, and ants carry it into their nests, eat the appendage and leave the seed underground — a partnership that explains why seedlings appear in odd, scattered places. The seed is also short-lived and has an undeveloped embryo, so it must be sown fresh and given a warm period followed by a cold one before it will germinate, often not until the second spring. The genus is a study in spurred flowers and pollinator specificity: the spurs hold nectar that only long-tongued bees can reach. The Chinese species are the source of icariin, the flavonoid behind the herb yin yang huo; the Japanese ornamentals, including this one, are grown for their flowers and carry much less of it.
Uses & Benefits
As a garden plant it is one of the best groundcovers for dry shade under deciduous trees, where it forms a dense mat that weeds cannot penetrate and where its spring flowers have no competition. It combines well with hellebores, ferns and snowdrops, and the foliage holds its shape through the season after the flowers have gone. The Chinese Epimedium species are the medicinal ones — E. brevicornum, E. sagittatum and E. koreanum are the pharmacopoeial sources of yin yang huo — and this Japanese species should not be sold as a substitute. Icariin from those species has been extensively studied in laboratory and animal work for effects on bone density and erectile function, with human evidence still thin and products frequently adulterated. Grow this one for the garden, not the pharmacy.
Growing from Seed
Sow fresh seed the day the capsule splits, on the surface of a mix of leaf mould and grit, and cover it with a thin layer of the same. Leave the pot outside through winter so that it gets the warm-then-cold sequence it needs, and do not throw it away when nothing appears in the first spring — germination is often in the second. Keep the compost moist but never wet. Alternatively, divide established clumps in late summer or early autumn, which is far quicker. Grow the plants in dappled or full shade, in soil with plenty of organic matter, and water through dry spells in the first year. Cut the old foliage back in late winter, before the flowers emerge, so the new growth and the blooms are seen clean.
Our Take
One of the finest perennials for dry shade, with flowers worth waiting for and a propagation quirk that explains a lot about ant biology.
Related Reading
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