Stems weakly erect to reclining, 10-30 cm, glabrous. Leaves basal and cauline; basal petioles 2 cm, distal petioles shorter. Leaf blade: basal usually ternately compound, distal gradually less divided; leaflets nearly orbiculate to orbiculate-reniform, apically 4-7-lobed, 20-30 mm wide, lobe margins crenate, surfaces abaxially glaucescent. Inflorescences panicles, few flowered. Flowers: sepals white, spatulate to rhombic-spatulate, 1.5 mm; filaments white, 2-3 mm; anthers 0.3-0.5 mm. Achenes 3-8, spreading; stipe 2.5-3.5 mm, nearly as long as achene body; body flat, 2.5-4 mm, abaxial margin convex, adaxial margin straight, conspicuously 3-veined on each face; beak minute. Flowering late spring-early summer (Jun). Moist sandstone bluffs, sinks, and rocky crevices; of conservation concern; 200-1500 m; Ala., Ga., Ky., N.C., Tenn. Thalictrum mirabile is very similar to T . clavatum . Field studies are in progress to clarify the status of this species.
Much like T. clavatum, and perhaps not specifically distinct, but more lax and delicate; filaments generally less than 3 mm; achenes 2.5-4 mm, straight on the upper margin, convex on the lower; stipe 2.5-3.5 mm, nearly equaling the achene. Wet sandstone cliffs; e. Ky. and Tenn. to Ala. June.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.