Collinsonia canadensis L.

Richweed

© SRTurner

Family - Lamiaceae

Habit - Perennial forb with short, thick, woody rhizomes.

Stems - Strongly ascending to erect, to 1 m, 4-angled, mostly unbranched, glabrous or sparsely and inconspicuously pubescent.

	Stem and node.
© SRTurner

Leaves - Opposite, petiolate, simple, ovate or elliptic, sharply pointed, toothed or scalloped, upper surface glabrous or sparsely pubescent, underside sparsely to moderately short-hairy and with sessile glands.

	Leaf.
© SRTurner

	Leaf adaxial.
© SRTurner

	Leaf abaxial.
© SRTurner

Inflorescences - Terminal pyrimidal panicles with open, racemose branches, with flowers 2 per node on short stalks. Bracts to 3 mm, lanceolate.

	Inflorescence.
© SRTurner

	Inflorescence.
© SRTurner

Flowers - Calyces 2.5-5.0 mm long, somewhat zygomorphic to nearly actinomorphic, bell-shaped, 15-nerved, glabrous in the mouth, usually slightly 2-lipped, the lobes minutely hairy and glandular on both surfaces, becoming enlarged and papery at fruiting. Corollas 12-15 mm long, zygomorphic, mostly yellowish, sometimes with dull purple to reddish brown markings, the surfaces glandular and pubescent, the tube funnelform, 2-lipped to about the midpoint, the upper lip shorter, the 4 lobes spreading to loosely ascending, with entire margins, the lower lip prominent, spreading, 1-lobed, this strongly fringed, mostly white. Stamens 2, strongly exserted and somewhat spreading. Ovary deeply lobed, the style appearing nearly basal. Style strongly exserted, with 2 slender branches at the tip.

	Flower.
© SRTurner

	Flowers.
© SRTurner

Fruits - Dry schizocarps, usually consisting of a solitary globose nutlet to 2.5 mm diameter, this glabrous, smooth and shiny, brown.

	Portion of infructescence.
© SRTurner

	Nutlets.
© SRTurner

Flowering - July - September.

Habitat - Forests, streambanks.

Origin - Native to the U.S.

Lookalikes - None.

Other info. - This striking and unmistakable species is found in Missouri mostly in the eastern half of the Ozark Division. Missouri lies at the far western extent of the plant's natural range, which extends eastward to coastal areas and also into Canada. The flowers are beautiful in intricate detail, with deeply fringed lower petal lips and strongly exserted stamens and style. The inflorescence emits a pleasant lemony fragrance. Steyermark noted that the roots have been used to alleviate kidney ailments, and numerous medicinal applications were practiced by Native Americans.

Photographs taken at Johnson's Shut-Ins State Park, Reynolds County, MO, 8-20-2013; also at Royal Gorge near Ketcherside Mountain, Iron County, MO, 8-26-2016, and Millstream Gardens Conservation Area, Madison County, MO, 9-3-2020 (SRTurner).