Northern Ontario Plant Database

Plant Description

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Thalictrum pubescens Pursh 1814, non Schleich. ex DC. 1817

En: tall meadowrue, king-of-the-meadow, late meadowrue, muskratweed, pubescent meadowrue, meadow-weed
Fr: pigamon pubescent

Ranunculaceae (Buttercup or crowfoot Family)

General: A tall, perennial forb, to 1.5 m tall, stems smooth (glabrous).

Leaves: Basal and alternate, pinnately compound (tripinnate), with 15–27 stalked leaflets. Stem leaves (cauline leaves) sessile, basal leaves on long petioles. Leaflet blades oblong to rounded (orbicular); smooth above, the lower surface smooth or with fine hairs; bases rounded; apices divided into 3 broad, blunt lobes; margins entire.

Flowers: Unisexual and bisexual; plants with unisexual male and female flowers on different plants (dioecious), or also with some bisexual flowers (polygamo-dioecious); flowers white, numerous, arranged in large terminal clusters (panicles). Sepals 4–5, oblong to obovate, blunt, falling soon after the flowers open (caducous), 2–3.5 mm long; petals lacking; stamens numerous, filaments 3.5–5 mm long, slightly swollen just below the anthers; pistils 4–15. Flowers bloom in last spring to mid summer.

Fruit: A cluster of small, fusiform achenes, smooth and ridged, 2.5–5 mm long.

Habitat and Range: Stream and riverbanks, marshes, wet meadows and thickets. The tall meadowrue is native to eastern North America; in Ontario, it extends as far north as Hearst.

Internet Images: The Thalictrum pubescens webpage from the Gallery of Connecticut Wildflowers, a website of the Connecticut Botanical Society.

Similar Species: Thalictrum dioicum (early meadowrue) can be recognized by the 5–7 terminal rounded lobes of each leaflet, actually 3 larger lobes each with 2–3 smaller lobes. Thalictrum dasycarpum (purple meadowrue) is most similar to Thalictrum pubescens; both have leaflets with 3-terminal lobes, but the filaments of T. dasycarpum are 1.5–3 mm long and the achenes are covered with short brown hairs.

Compare the tall meadowrue to the Thalictrum dioicum (early meadowrue) webpage from the Gallery of Connecticut Wildflowers, a website of the Connecticut Botanical Society, and the Thalictrum dasycarpum webpage from the Missouriplants.com website.

Comparison of common Thalictrum species in northern Ontario

	Thalictrum pubescens (tall meadowrue)	Thalictrum dasycarpum (purple meadowrue)	Thalictrum dioicum (early meadowrue)
leaflets	usually with 3 terminal lobes		usually with 5–7 terminal lobes
upper stem leaves	sessile		with distinct petioles
filament colour and shape	white, thickened below the anther	white, slender	purple
anther length	0.8–1.5 mm long	1.5–3.5 mm long	2–3.5 mm long
fruit surface	smooth or hairy	with brownish hairs	smooth
flowering time	summer (June–August)	late spring–summer (Late May–July)	spring (April–May)

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