Trees to 12 m tall, glabrous except for flowers. Petiole 3-5 mm; leaf blade oblong, 6-16 × 2.5-4.5 cm, papery, midvein abaxially elevated and adaxially impressed, secondary veins 15-19 on each side of midvein, abaxially slightly prominent, and adaxially flat, base broadly cuneate to obtuse, apex caudate with a 1-1.7 cm tip. Inflorescences leaf-opposed, 1-flowered. Pedicel ca. 3 mm, puberulent. Flower buds conic, ca. 10 × 8 mm. Sepals triangular, outside tomentulose, inside glabrous. Outer petals ovate-triangular, ca. 10 × 6 mm, outside tomentulose, inside glabrous; inner petals ca. 9 × 5 mm. Stamens many, in 3 whorls, ca. 1.5 mm; connectives apically apiculate. Carpels 4 or 5, oblong, slightly flat, hirsute; ovules 5 per carpel, in 2 series; styles short; stigmas apically 2-cleft. Fruiting carpels oblong, ca. 4 × 2.5 cm, densely tomentose. Fl. Apr-Jun, fr. Aug-Oct.

Alphonsea tsangyuanensis is listed as Endangered (EN B2ab (i,ii,v)) by the IUCN Red List of Threatened Species (Version 2010.3; http://www.iucnredlist.org; accessed on 8 Oct 2010). The type collection of this species (Q. W. Wang 73312) was originally identified as A. lutea J. D. Hooker & Thomson (C. Y. Wu & W. T. Wang, Acta Phytotax. Sin. 6: 210. 1957).

● Forested slopes; 700-1500 m. S Yunnan.