Mint family (Lamiaceae)
Creeping perennial with above-ground stolons. Four-sided flower stems erect, reaching up 15-60 cm. Leaves positioned in opposite pairs, 3-12 cm long and partially evergreen, dark green in colour and stalked. Blade ovate-lanceolate, irregularly toothed on margins. Flowers sessile, 1.5-2.5 cm long, clustered in verticillasters of 6-10 each located in axils of upper leaves. Calyx bell-shaped, with 5 segments. Corolla zygomorphic, yellow, 15-25 mm long. Lower lip with pointed petals, upper hooded with hairy margins. Flowers Apr.-Jun.
Grows in mesic, fertile soils of oak-lime-hornbeam and riparian forests. A medicinal plant.
Descriptions devised by the team at the Independent Department of Forest Botany, Warsaw University of Life Sciences, i.e. L. Witkowska-Żuk, K. Marciszewska, W. Ciurzycki, A. Obidziński and P. Zaniewski