Ballota nigra L.
black horehound
Perennial herb, with hairy stems to c. 1 m tall. Petioles 1-3 cm long. Lamina of upper cauline lvs 2.5-5 × 2-3 cm, ovate or ovate-oblong, densely hairy on both sides, strongly crenate; base subcordate; apex acute. Verticels dense; bracts cuneate, serrate or crenate-serrate. Bracteoles < calyx, ± filiform. Calyx 6-9 mm long, with nerves densely hairy; teeth ovate, acuminate. Corolla 12-15 mm long, pinkish to purple or white, almost glabrous outside; middle lobe ovate and slightly reflexed. Filaments hairy at base. Nutlets not seen.
N.: known with certainty only from a quarry on Mt Wellington, Auckland.
Europe, N. Africa, W. Asia 1957
FL Feb.
When not in flower, black horehound is difficult to distinguish from several other labiates, for example Nepeta cataria, and so further collections of this sp. from the Auckland region may well exist among unidentified sterile material. B. pseudodictamnus L. is sometimes cultivated, but is easily distinguished by the orbicular, white, woolly lvs.
