Linnaeus, Syst. Nat. ed. 10. 2: 1131. 1759.
O. E. Schulz;
(Britton) O. E. Schulz
(slender); glabrous or sparsely to densely pubescent throughout.
(simple or few to several from base), erect, (somewhat flexuous), often branched distally, (0.5-)1-3(-4) dm.
(often withered by anthesis), usually not rosulate, pinnately (5 or) 7-13(-17)-foliolate, (2-)4-10 cm, leaflets sessile or petiolulate; petiole 0.5-2.5(-4.5) cm; lateral leaflets similar to terminal, sometimes smaller; terminal leaflet (sessile or petiolule to 0.5 cm), blade linear to oblong, oblanceolate to obovate, or suborbicular, (0.1-)0.3-1 cm × 1-7 mm, base cuneate, margins entire or 3(-5)-toothed or -lobed.
5-10(-14), (5-)9-15(-17)-foliolate, petiolate, leaflets sessile; petiole 0.3-1 cm, base not auriculate; lateral leaflets similar to terminal, sometimes smaller; terminal leaflet blade filiform, linear, or narrowly oblong, 0.3-1(-1.6) cm × 0.3-3 mm, margins usually entire, rarely 1-3-toothed.
divaricate or ascending, 4-10 mm.
sepals oblong, 1-1.5(-2) × 0.3-0.5 mm, lateral pair not saccate basally, (margins membranous); petals white, oblanceolate, (1.5-)1.8-2.5(-3) × 0.4-0.8(-1) mm; filaments 1.4-2.5 mm; anthers ovate, 0.2-0.4 mm.
linear, (torulose), (0.5-)1-2(-2.5) cm × 0.6-0.9 mm; ovules 20-50 per ovary; style 0.3-0.7(-1) mm.
pale brown, oblong-ovoid, 0.6-0.9 × 0.4-0.6 mm, (narrowly margined or not).
Flowering Mar-Jun. Roadsides, stream banks, rocky crests and outcrops, crevices of granitic bedrock, dry woods, glades, fallow fields, disturbed ground, limestone barrens, marsh and swamp margins, floodplains, waste ground, slopes, ledges, cliffs, meadows; 0-1500 m; Alta., B.C., Man., N.B., Nfld. and Labr. (Nfld.), N.W.T., Ont., Que., Sask.; Ala., Ark., Conn., Del., D.C., Fla., Ga., Idaho, Ill., Ind., Iowa, Kans., Ky., La., Maine, Md., Mass., Mich., Minn., Mo., N.H., N.J., N.Y., N.C., Ohio, Okla., Oreg., Pa., R.I., S.C., Tenn., Tex., Vt., Va., W.Va., Wis.; Eurasia.
in the broad sense, two species or varieties have been recognized: the Eurasian
) versus the North American
). Nuclear DNA data suggested a sister relationship of the North American and Eurasian entities, while cpDNA data showed them intermingled (J. Lihová et al. 2006). There are no apparent morphological differences between these entities, although detailed morphological studies are still lacking. We currently prefer to treat them as a single taxon.