Description from Flora of China
Shrubs ca. 5 m tall. Terminal buds and young branchlets brown pubescent; old branchlets glabrous, sparsely and inconspicuously lenticellate. Leaves clustered at branchlet apex; petiole 5–10 cm; leaf blade shiny adaxially, dark green after drying, narrowly oblong, 6–9 × 2–3.5 cm, hard leathery, glabrous abaxially, lateral veins ca. 5-paired, visible abaxially, indistinct adaxially, reticulate veins indistinct on both surfaces, base cuneate, apex acute. Inflorescences terminal, umbellate or racemose, ca. 2 cm, brown pubescent; peduncle very short; bracts deciduous; bracteoles lanceolate, ca. 1 mm, pubescent; pedicels 5–8 mm, pubescent. Sepals ovate, ca. 2 mm, apex obtuse. Petals 6–7 mm. Stamens ca. 5 mm. Ovary pubescent; placentas in middle part of valves; ovules ca. 4; stipe very short. Style pubescent proximally. Capsule globose, 6–8 mm in diam., glabrous, dehiscing by 2 valves; pericarp thinly woody, horizontally striate adaxially. Seeds ca. 4, compressed globose, ca. 5 mm; funicle very short. Fl. Jan–May, fr. Jan–Oct.
This species is the only one in China with an umbellate-racemose inflorescence. Gowda (J. Arnold Arbor. 32: 337. 1951) included Pittosporum tonkinense in the synonymy of P. tetraspermum Wight & Arnott, which, in the strict sense, is distributed in India. Pittosporum calcicola C. Y. Wu (in W. C. Yin, Fl. Yunnan. 3: 326. 1983) was described from Xichou Xian, SE Yunnan, and was said to differ from P. tonkinense in several characters, but these fall within the range of variation of P. tonkinense. The name is anyway invalid under Art. 8.1 and 37 of the St. Louis Code because two type specimens were indicated.
Forests, slopes, limestone areas, roadsides; 600--1800 m. Guangxi, Guizhou, SE Yunnan [Vietnam].