This section is from the book "An Illustrated Flora Of The Northern United States, Canada And The British Possessions Vol2", by Nathaniel Lord Britton, Addison Brown. Also available from Amazon: An Illustrated Flora of the Northern United States, Canada and the British Possessions. 3 Volume Set..
Thalictrum dioicum L. Sp. Pl. 545. 1753.
Glabrous, erect, 1°-2° high, slender, leafy. Roots not yellow; leaves 3-4-ternate; leaflets thin, pale beneath, orbicular or broader, often cordate and the terminal one somewhat cuneate, 5-9-lobed; flowers dioecious, greenish, drooping or spreading; panicle elongated, of numerous lateral corymbs or umbels; filaments longer than the sepals; anthers linear, blunt, longer than the filaments; stigma elongated; achenes ovoid, sessile or minutely stipitate, strongly ribbed, much longer than the style.
In woods, Maine to Alabama, Saskatchewan and Missouri. Ascends to 4500 ft. in North Carolina. Poor-man's rhubarb. Shining grass. Quicksilver-weed. Feathered columbine. April-May. Recorded from Labrador.
Thalictrum polygamum Muhl. Cat. 54. 1813. Thalictrum Cornuti T. & G. Fl. N. A. 1: 38. 1838. Not L. 1753.
Stout, 3°-11° high, branching, leafy, smooth or pubescent but not glandular nor waxy. Leaves 3-4-ternate; leaflets moderately thick, light green above and paler beneath, oblong, obovate or orbicular, with 3 main apical pointed or obtuse lobes; panicle compound, leafy, a foot long or more; flowers polygamous, white or purplish; filaments broadened, narrowly clavate; anthers oblong, short; achenes ovoid, short-stipitate, 6-8-winged, glabrous or pubescent.
Several additional species of Thalictrum from within our range have been described by Professor Greene, at least some of which are referable to T. polygamum as races.