General:
Perennial herb from a creeping rhizome; finely-hairy throughout, rarely with longer spreading hairs; stems erect, simple or branched above, 30-70 cm tall, 4-angled.
Leaves:
All stem leaves; opposite, lanceolate to broadly egg-shaped, 2.5-8 cm long, 1-3 cm wide, more or less sharply toothed; stalks to 1.5 cm long.
Flowers:
Inflorescence a single, large, terminal, head-like cluster, closely surrounded by leaf-like bracts; corollas tubular, 2.5-3.5 cm long, purple, finely-hairy, strongly 2-lipped, the upper lip narrow and arc-shaped and bearded at tip, the lower lip spreading and 3-lobed; calyces tubular, 7-11 mm long, the teeth only 1 mm long, the opening white-hairy within and sometimes also outside, 15-veined.
Fruits:
Nutlets, 4 clustered together, oblong, smooth.
Notes:
Two sympatric varieties occur in BC:
1. Leaves with stalks to 1.5 cm long; stems usually branched above................ var. mollis (L.) Benth.
1. Leaves with stalks less than 0.5 cm long; stems usually simple.................. var. menthaefolia (Grah.) Fern.
Source: The Illustrated Flora of British Columbia