24. Dunnia Tutcher, J. Linn. Soc., Bot. 37: 69. 1905.
绣球茜属 xiu qiu qian shu
Authors: Tao Chen & Charlotte M. Taylor
Shrubs, unarmed; branches sometimes rather stout. Raphides present. Leaves opposite, without domatia; stipules persistent, interpetiolar, generally triangular, acute to bifid. Inflorescences terminal, corymbose-cymose, several to many flowered, pedunculate, with peduncles usually elongated and flexuous, bracteate, with some bracteoles on most inflorescences fused to base of hypanthium, expanded, and petaloid thus appearing to be a calycophyll. Flowers subsessile to shortly pedicellate, bisexual, distylous. Calyx limb 4- or 5-denticulate, sometimes 1 or a few flowers with 1 petaloid calycophyll. Corolla yellow, salverform or funnelform, villosulous inside; lobes 4 or 5, valvate in bud. Stamens 4 or 5, inserted in upper part of corolla tube, included or partially exserted; filaments short; anthers apparently dorsifixed. Ovary 2-celled, ovules numerous, position of placentas unknown; stigma 2-lobed, included. Fruit capsular, subglobose to obovoid, apically prolonged into a short beak, stiffly cartilaginous or leathery, septicidally dehiscent into 2 valves with each valve sometimes later splitting into 2 parts, with calyx limb, petaloid bracts, and calycophylls persistent; seeds small, flattened, with marginal wing membranous, irregular or lacerate; endosperm abundant; embryo minute.
Two species: China, India; one species (endemic) in China.
The stipitate petaloid structures on the inflorescence are similar to the petaloid calycophylls of other Rubiaceae genera; however, these appear to comprise two different morphological structures. Most of these structures appear to be inserted at the base of the ovary and thus can be considered bracts, but some appear to be enlarged calyx lobes inserted above the ovary.
Dunnia was revised by Ridsdale (Blumea 24: 367-368. 1979).