Description from Flora of China
Benzoin kariense (W. W. Smith) Handel-Mazzetti; Lindera kariensis f. glabrescens H. W. Li.
Deciduous shrubs or trees, 2-10 m tall, up to 20 cm d.b.h. Bark gray-white. Branchlets cylindric, laxly yellow-brown puberulent, later glabrate; current year branchlets brownish, becoming gray or grayish black, lenticellate, lenticels ovate, exserted and longitudinally split. Leaves alternate; petiole 0.5-1.5 cm, brown pubescent, becoming glabrous; leaf blade elliptic, obovate, or oblanceolate, (3-)5.5-6.5(-9.5) × (1.5-)3-3.5(-4.5) cm, membranous, papery at maturity, greenish and densely brown pubescent along veins, later glabrate abaxially, green and laxly brown puberulent along veins, becoming glabrous or nearly glabrous adaxially, or glabrous on both surfaces, pinninerved, lateral veins 4 or 5 pairs, slightly distinct abaxially, base broadly cuneate or subrounded, apex rounded. Umbels (2 or)3-6-flowered, inserted in leaf axil at apex of current year branchlet, not pedunculate; involucral bracts early deciduous. Male flowers green-yellow or nearly white; pedicels (3-)5-7 mm, slender, densely dirty yellow pubescent; tepals 6, ovate or broadly ovate, 3.5-4 × ca. 3 mm, apex rounded, laxly yellow-brown pubescent on dorsal keel; stamens 9, ca. 2 mm; filaments equal to length of anther, 2-glandular; glands broadly reniform, stipitate; reduced pistil very small, less than 1 mm, glabrous; style and stigma small mucro-shaped. Female flowers yellow-green; tepals 6, broadly ovate, ca. 3.5 × 2.5 mm, obtuse at apex, laxly yellow-brown pubescent on dorsal keel; reduced stamens 9, ca. 1.5 mm; filaments rather thick, 2 × length of anther, 2-glandular at base in 3rd whorl; glands ovate, shortly stipitate; anthers sterile; ovary ovate, ca. 2 mm; style equal to length of ovary, slender; stigma peltate, papillose. Fruit ovate to subglobose, ca. 0.8 × 7 mm, mucronate at apex, glabrous; stipes 2-3 mm, later glabrous. Fl. Mar-Jun, fr. Jul-Oct.
Two forms have been recognized: f. kariensis, with leaf blade pubescent on both surfaces or only abaxially, and f. glabrescens (无毛山胡椒 wu mao shan hu jiao), with leaf blade glabrous on both surfaces or at first pubescent adaxially and later glabrate.
● Mixed forests, thickets, bamboo forests or forest margins on mountain slopes or at ravine sides, Rhododendron forest margins; (2700-)2800-3700 m. W Yunnan.