Wikipedia
Cyathocalyx
Cyathocalyx is a small genus with about 22 species distributed from southern India, Sri Lanka, through Malaysia, Indomalayan islands and reaches as far as Fiji in the South Pacific.
The salient features of the genus includes- monopodial trees, supra-axillary or nearly leaf-opposed inflorescences, six petals which are basally concave and constricted above the reproductive organs to form a "pollination chamber".
The genus consists 22 identified species with two unresolved species.