Erect perennial, usually single-stemmed. Infloresence in spikes, terminal on stem and from leaf axils. Flowers are pink, irregular, tubular, flowers oppositely placed on the spikes. We measured flowers to 20 mm long. Leaves are cauline, opposite, sessile, lanceolate, serrate. A large leaf was measured at 13 cm long and 3.5 cm wide. Stems square and glabrous. Leaves with tiny hairs on the top, and glabrous on the bottom.
Height listed in Budd's Flora to 100 cm, we measured plants to 80 cm tall. Fairly common.
There is one other species of Physostegia native to our province, P. parviflora, which can be distinguished by its uppermost leaves which are broadest near the broadly rounded base, and a corolla usually less than 1.5 cm long (as listed in The Flora of Canada).
Habitat is stream banks, moist woods, we've seen them growing in both sun and shade.
The above photos were taken August 5th along the Red Deer River, 400 km north east of our home in Regina, SK.