Herbs, perennial, 50-120 cm tall. Young rootstock with single head, 2-3 × 1-1.2 cm, thickened when old with 2 or 3 heads and few fibrous roots. Stems pale brown, shiny, hollow, ca. 1 cm in diam., naked below, leafy and sparingly branched above. Radical leaves 2-4 × ternate to pinnate. Cauline leaves glaucous abaxially, dark green adaxially, biternate to pinnate; ultimate leaflets unequally deeply 2-or 3-divided; segments lanceolate, 3-7 × 1.5-3 cm. Racemes simple or sparingly branched at base, densely 10-20(-50?)-flowered; axillary inflorescence smaller; bracts linear, usually shorter than 3-6 mm erect pedicels, or lowermost bract(s) much larger. Sepals early falling, ovate to oblong, 4-10 × 2-4 mm, entire, acute. Flowers nutant, purplish red to almost red. Upper petal 3-4 cm, apex acute, ± curved; spur straight (upcurved in bud), broad, slightly narrowed toward obtuse apex, 20-27 mm, ca. 2 × as long as limb or more; nectary extended through ca. 2/3 of spur; lower petal navicular, 11-12 mm; inner petals 9-10 mm. Stigma oblong, upper part with 4 papillae, base with 2 papillae. Capsule obovoid, 7-9 × 3-4 mm, explosively dehiscent; style ca. 4 mm. Seeds angular, ca. 3 mm, smooth, with small elaiosome. Fl. Jun-Aug.
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