Description from Flora of China
Sambucus buergeriana (Nakai) Blume ex Nakai var. mi-quelii Nakai; S. racemosa Linnaeus subsp. sibirica (Nakai) H. Hara; S. williamsii Hance var. miquelii (Nakai) Y. C. Tang ex J. Q. Hu.
Shrubs, 2-4 m tall, densely branched. Bark reddish brown, longitudinally sulcate, with elliptic lenticels; pith brownish; young branches yellowish white hirsute, sometimes papillose. Leaflets 2-jugate, abaxially pale, adaxially green, ovate-lanceolate to lanceolate, 5-14 × 1.6-5.5 cm, midvein long hirsute, base cordate and oblique, margin irregularly acutely toothed, apex long acuminate; petiolule and leaf rachis yellow hirsute; stipules glandular. Inflorescence an erect cymose panicle, 3.5-5 cm; peduncle papillose. Flowers opening with leaves; calyx tube urceolate, ca. 1 mm, lobes triangular-lanceolate, slightly shorter than tube; corolla greenish or yellowish, lobes oblong; stamens yellowish brown; anthers yellow; ovary 3-loculed; styles short; stigmas 3-lobed. Fruit red, ovoid or subglobose, 3-5 mm in diam.; pyrenes 2 or 3, ovoid to ellipsoid, 2.5-3.5 mm, slightly rugose. Fr. Jul-Aug. 2n = 18, 36, 38*.
Sambucus sibirica should perhaps be included within S. williamsii. The differences separating them, i.e., young branches, petiolule, and leaf rachis slightly pubescent vs. glabrous in S. williamsii, are minor.
Rocky mountain slopes, rock crevices along rivers. Heilongjiang, Jilin, Liaoning, Xinjiang [Mongolia, Russia].