Epilobium tetragonum L.

Rank, clump-forming perennial herb 10-130 cm tall; stems branched from base, producing leafy basal rosettes in autumn; stems strigillose all round above, and with raised lines running down from bases of petioles. Lvs mostly opposite, alternate in infl., sessile and decurrent into the raised lines on stem, dark bluish green, often tinged with red, 1.5-7.5 × 0.3-1.5 cm, evenly serrate or serrulate, narrow-lanceolate to narrow-elliptic, strigillose on midrib and margins; base attenuate to truncate; apex acute or acuminate. Infl. erect, densely strigillose. Fls erect. Ovary 3-5 cm long, strigillose. Floral tube 0.8-1.1 mm deep, strigillose outside, with a conspicuous rim of dense, long hairs inside. Sepals 2.8-4.5 × 0.8-1.8 mm, strigillose, somewhat keeled. Petals pale mauve to rose-purple, 2.5-5.5-(7) × 2-3.5-(4.5) mm. Filaments of the longer stamens 1.3-3 mm long. Style 1.5-3.2 mm long, glabrous or nearly so, white, sometimes rosy purple near base; stigma clavate, 1.8-3 mm high. Capsule strigillose, (3.5)-5-11.5 cm long; fruiting pedicel 1-3 cm long. Seeds 0.8-1.3 × 0.4-0.5 mm, obovoid, coarsely papillose.

Damp woodland clearings, hedgebanks, ditches and cultivated soil. Spring bogs, flooded meadows, banks of streams.

Can be grown by seedlings.