Smartweed

(Polygonum hydropiper L., Polygonaceae)

Also Called: Water Pepper, Biting Persicaria.

Description: Annual plant 30 100cm (12-40in) high, stems branched, often tinged with red and inflated at the nodes. Leaves more or less lanceolate, glabrous (apart from marginal fringe of hairs) and dotted with small transparent glands. Flowers in loose spikes, small (2-4mm 0.07-0.15in), green or reddish, tunnel-shapped, dotted with transparent glands. All parts of the plant have a pungent taste resembling pepper.
Flowering: July, August.

Part Used: Entire plant, fresh or dried; less active when dried.

Habitat and Collection: In wet ditches, on edges of streams, damp parts of woods, rarely in pastures, throughout Europe, abundant in England. Collected when in flower and dried in the shade at not greater than 45°C (113°F).

Constituents and Action: 1. Tannin, astringent and anti-inflammatory. 2. A pungent principle that reddens or even blisters the skin. It is diuretic, haemostatic and an emmenagogue.

Usage: The bruised fresh plant is applied to wounds slow to heal, to bruises and for rheumatism. The powdered dried plant (2-3 knife-pointfuls daily) or as a tisane (a tablespoonful infused in 1 litre (1•75pt) of water) is used for generalised oedema, for amenorrhoea and as an emmenagogue. Its efficacy in menstrual disorders is doubtful.