Aconitum napellus Linnaeus var. sessiliflorum Finet & Gagnepain, Bull. Soc. Bot. France 51: 513. 1904; A. rotundifolium Karelin & Kirilov var. sessiliflorum (Finet & Gagnepain) Rapaics.

Caudex unknown. Stem 65--120(--150) cm, simple, or 1-branched below inflorescence, basally glabrous, apically sparsely retrorse pubescent, with crowded leaves. Proximal cauline leaves withered at anthesis, middle ones slightly long petiolate or shortly petiolate; petiole 1.5--3.5 cm, glabrous; leaf blade pentagonal-orbicular, ca. 5 × 8 cm, both surfaces glabrous or sparsely pubescent, base deeply cordate, 3-sect; segments sessile; central segment broadly rhombic, subpinnatisect; ultimate lobes linear-lanceolate, 2.5--3 mm wide; lateral segments obliquely flabellate, unequally 2-parted. Inflorescence terminal, 10--30 cm, 9--20-flowered; rachis and pedicels retrorse pubescent; proximal bracts leaflike or 3-fid, others linear or spatulate-linear. Pedicels 0.3--3 cm, with 2 bracteoles ± bordering flower; bracteole oblong or palmate, 7--10 × 2.5--4 mm. Sepals blue-purple, abaxially sparsely pubescent; lower sepals narrowly ovate; lateral sepals 1.5--1.6 cm; upper sepal galeate, 2--2.5 cm high, shortly beaked. Petals glabrous; lip ca. 5 mm; spur incurved, ca. 2 mm. Stamens sparsely pubescent; filaments entire. Carpels 5, densely appressed pubescent. Fl. Aug. 2n = 16*.

* Scrub, grassy slopes; 3500--4100 m. W Sichuan, ?Yunnan.