Description from Flora of China
Arabis kandingensis Y. H. Zhang; Sisymbrium luteum (Maximowicz) O. E. Schulz var. yunnanense (W. W. Smith) O. E. Schulz.
Herbs perennial, (0.6-)0.8-1.5(-2.2) m tall. Stems erect, branched above, sparsely to densely pilose at least near base, usually glabrous above. Basal leaves not seen; petiole of middle cauline leaves 1-3.5 cm; leaf blade ovate-lanceolate, lobed near base, 8-16 × 2-7 cm, pilose abaxially, often glabrous adaxially, base often hastate or truncate, or rarely cuneate, margin dentate with apiculate callosities, apex acuminate. Uppermost cauline leaves linear-lanceolate, margin entire or sparsely denticulate, apex acuminate. Racemes basally bracteate. Fruiting pedicels ascending or subdivaricate, stout, narrower than fruit, (0.7-)0.9-1.3 cm. Sepals linear, ascending, 3.5-5.5(-7) × 1-1.3 mm, subapically cucullate. Petals yellow, narrowly spatulate, 6-8(-10) × 1-1.5 mm; claw subequaling sepals. Filaments yellowish, erect, 3-5(-6) mm; anthers oblong, 1-1.5 mm. Ovules 70-100 per ovary. Fruit narrowly linear, terete, (6-)8-13 cm × 0.9-1.5 mm; gynophore to 2 mm; valves glabrous, torulose, somewhat prominently veined; style stout, 0.5-1 mm; stigma slightly 2-lobed; septum slightly thickened or membranous. Seeds oblong, 1.4-2 × 0.6-0.8 mm, inserted in depressions of septum. Fl. Jun-Jul, fr. Jul-Aug. 2n = 28*.
Although the present authors have not examined the type of Arabis kandingensis, the excellent description and illustration (Bull. Bot. Res., Harbin 14: 144-146. 1994; ibid. 18: 156-157. 1998; Fl. Sichuan. 14: 117. 1999) leave no doubt that it is a synonym of Sisymbrium yunnanense. It was described as having yellow flowers, exclusively simple trichomes, and chromosome number based on x = 7. No species of Arabis has any of these characters. Arabis kandingensis perfectly matches the above description of S. yunnanense in all characters.
Sisymbrium yunnanense was recognized in FRPS as a variety of S. luteum, but the differences between the two taxa (see the above key) are significant enough to support their recognition as distinct species.
* Thickets, ravines, mountain slopes, by streams; 2000-3000 m. Sichuan, Yunnan.