Epilobium

Scientific name

Epilobium L.

Common names

willowherb

Family

Onagraceae

Native distribution

worldwide; mostly temperate

Species cultivated

Epilobium angustifolium L.

E. ciliatum Raf. [offered under the synonym E. glandulosum Lehm.]

E. coloratum Biehler

E. dodonaei Vill.

E. fleischeri Hochst.

E. glabellum G.Forst.

E. leptophyllum Raf.

E. parviflorum Schreb.

Adventive distribution

several species are introduced throughout the world

Weed status

Epilobium hirsutum L. is an aquatic noxious weed in at least one country.

Habit

amphibious, seasonally inundated or occasionally emergent herb; small to medium, often mat-forming

Brief description

Survives unfavorable seasons via leafy rosettes, turions or stolons. Stems erect to ascending, simple or branched, typically round. Foliage glabrous to densely pubescent. Leaves opposite, becoming alternate above and bract-like in the inflorescence; subsessile to petiolate; leaf blade variable, typically lanceolate to elliptic or oblong to ovate; apex and base variable; margins entire to serrate. Inflorescence a spike, raceme, or panicle, or flowers solitary in leaf axils; flowers white to rose-purple or yellow; sepals 4, typically lanceolate, free or basally connate; floral tube often has an internal ring of villous hairs; petals 4, typically notched apically.

Natural habitat

seasonally inundated or permanently moist to wet habitats in montane to alpine areas; near, along, or in wet meadows, secondary floodplain forests, seeps, lakes, streams and rivers in temperate regions.

Additional comments

Few Epilobium species are truly aquatic, though many are amphibious to varying degrees (occasionally to permanently), especially during the early spring when water levels are high. Epilobium ciliatum is the most widespread and abundant species of Epilobium worldwide. Among the over 200 species in the genus, eight are commonly cultivated in the trade; most are mainly terrestrial but may be found near or in various water sources.