3. Cyathostemma Griffith, Not. Pl. Asiat. 4: 707. 1854.
杯冠木属 bei guan mu shu
Authors: Bingtao Li & Michael G. Gilbert
Shrubs, climbing. Inflorescences terminal, extra-axillary, or often leaf-opposed; flowers solitary or in pendulous and few-flowered cymes from branches or trunk. Flowers bisexual or unisexual, subglobose. Pedicel bracteate. Torus flattened, margins prominent. Sepals 3, valvate, connate at base, usually hirsute. Petals 6, biseriate, short, subequal or inner smaller, imbricate at apex, valvate at base remaining incurved. Stamens numerous, oblong; anthers subintrorse; connectives oblique, incurved. Carpels numerous; ovules few to numerous per carpel, in 2 series; styles cylindric, glabrous; stigma conical, 2-cleft at apex. Fruit apocarpous, pedicellate; monocarps stipitate, oblong or ovoid. Seeds several per monocarp, in 2 series.
About ten species: China, Indonesia, Malaysia, Thailand, Vietnam; one species in China.
Cyathostemma was included in Uvaria on the basis of a recent molecular study by L. L. Zhou et al. (Syst. Biodivers. 7: 249-258. 2009). This study included 25 species of Uvaria and seven species of Cyathostemma (but not C. yunnanense) and showed the Cyathostemma spp. to form two separate groups nested within Uvaria and separated by four species of Uvaria. One of us (Gilbert) believes that this shows Zhou et al. were right to transfer all species of Cyathostemma to Uvaria.