I.C. Hedge & A. Paton

Perennial herb with a slender creeping rhizome. Stems 20-60 cm, ascending or erect, acutely quadrangular, leafy, simple or branched with very short crisped retrorse eglandular white hairs. Leaves oblong-lanceolate, 7-45 x 3-15 mm, decreasing in size up the stem, weakly crenulate, sometimes revolute, cordate-truncate, acute, with a very short eglandular indumentum denser below, upper surface sometimes glabrous; lower leaves with a petiole up to 2 cm, upper sessile. Inflorescence lax, terminal; flowers secund, in axils of upper leaves. Pedicels 1-1.5 mm, erect-spreading, with very small basal scales, terete. Calyx 3-3.5 mm in flower, enlarging in fruit to 4.5 mm and with a 2 mm high scutellum, with a similar indumentum but denser to that of stem. Corolla blue to violet-blue with some white markings, 12-16 mm, densely pilose; tube 8-10 mm; lower lip glabrous. Nutlets prominently tuberculate, orange-brown, c. 1.5 x 1 mm.

Fl. Per.: July-September.

Type: Europe (LINN 751/6!).

Distribution: Temperate Eurasia, N. America (the only species of the genus to be found in both the Old and New Worlds).

A species of wet or irrigated places, characterized by the weakly crenulate leaves and the blue/violet-blue flowers borne in the leaf axils.