Epilobium hirsutum Seeds | Great Willowherb

Fine, pale brown Great Willowherb seeds, each with a parachute of silky hairs, on a plain background — Great Willowherb (*Epilobium hirsutum*): Onagraceae, native to the wetlands of Europe, Asia and North Africa.

LATIN NAME: Epilobium hirsutum

COMMON NAME: Great Willowherb

Plant Profile

Great Willowherb is the largest of the European willowherbs, a softly hairy perennial with erect, branched stems one to two metres tall. The leaves are lance-shaped, toothed and clasp the stem, and from July the upper stems carry flat-facing, rose-purple flowers about two centimetres across, each with four notched petals and a white, four-lobed stigma that stands out like a cross.

It is a plant of ditches, riverbanks, fens and wet hedgerows across Europe, western Asia and North Africa, and it often forms large clonal patches where the ground stays damp. The whole plant has a faint, sweetish scent that is strongest in the evening.

Science & Biotechnology

Great Willowherb spreads both by seed and by fleshy stolons that run just below the surface, so a single introduction can become a stand within two seasons. The flowers are strongly protandrous and self-compatible, and the long white stigma is held clear of the anthers, a layout that encourages cross-pollination by long-tongued bees and hoverflies while leaving selfing as a fallback.

The plant accumulates oenothein B, an ellagitannin shared with other Epilobium species and the compound most often cited in work on the genus. It also hybridises readily with Small-flowered Willowherb where the two grow together, producing intermediate plants that complicate identification in mixed wetland sites.

Uses & Benefits

In the garden it is a plant for the wet margin: a pond edge, a bog bed or a ditch that never quite dries. There its height and long flowering season make it useful at the back of a border, and the flowers are among the best late-summer sources of nectar for bumblebees.

Young shoots are edible cooked, though the plant is not grown for the table. Willowherb herb has a long European record as a tea for urinary and prostate complaints, and Great Willowherb is one of the species gathered for that purpose, although the smaller-flowered species are more often used today. The seed heads that follow release their fluff in late summer, and finches line their nests with it.

Growing from Seed

The seed is fine and light-demanding: sow on the surface of a moist seed compost, press it in, and keep the tray in bright light without covering it. A few weeks of cold, damp conditions before sowing improves the percentage that germinates, but fresh seed will usually come up at 18 to 20 °C within three weeks.

Pot the seedlings on while they are small and keep them wet; this is not a plant that tolerates drying out at any stage. Set them out at the water’s edge or in any soil that stays moist, in sun or part shade, and expect flowering in the second summer. Where it is too happy it seeds and runs freely, so site it where spreading is an asset. In a small garden, lift and divide the stand every third year to keep it from crowding out smaller wetland plants.

Our Take

A tall, soft-leaved willowherb for wet ground, flowering for months and feeding bumblebees when the border is thinning out. It wants moisture and space, and gives both back.

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