Lycopus uniflorus (Northern Water-Horehound) - photos and description




Sepals are ovate with blunt points


General: Erect plants with leafy stems, stems usually simple, occasionally branching mid-stem. Stems square, glabrous to sparingly hairy. Plants rhizomatous.

Flowers: Small white flowers in whorls in leaf axils, we measured flowers to 3 mm long. Calyx lobes are ovate in shape and blunt at the apex.

Leaves: Leaves cauline, opposite, serrate, lanceolate. The plants we observed had very short,winged petioles, the leaves are also described as sessile. We measured a large leaf blade (no petiole) at 6.5 cm long and 2.5 cm wide.

Height: Height listed in Budd's Flora to 70 cm, we measured plants to 50 cm tall.

Habitat: Stream banks, swamps, and other wet areas. I have only found this plant in the boreal forest, never south of Greenwater Provincial Park / Hudson Bay district.

Abundance: Checklist of the Vascular Plants of Saskatchewan lists this plant as common.

Origin: Native.

Synonym: Listed in some of the field guides we use as Lycopus virginicus var. pauciflorus.

Similar species: Very similar in appearance to Lycopus asper, however, L. uniflorus has ovate-shaped and blunt pointed sepals, while L. asper has sepals which are narrow and acute.

When and where photographed: The above photos were taken August 4th, near Hudson Bay about 425 km northeast of our home in Regina, SK.