Description from Flora of China
Duhamelia Persoon; Tangaraca Adanson.
Shrubs, unarmed. Raphides absent. Leaves opposite or verticillate, usually with domatia; stipules persistent, interpetiolar, triangular. Inflorescences terminal, cymose with axes often helicoid and secund, many flowered, bracteate or bracts reduced. Flowers sessile to pedicellate, bisexual, monomorphic. Calyx limb 5-lobed. Corolla red to orange or yellow, tubular [to ventricose or funnelform], glabrous inside; lobes 5, imbricate in bud. Stamens 5, inserted at base of corolla tube, included or partially exserted; filaments short; anthers dorsifixed, 2-lobed at base, with connective flattened and prolonged at apex. Ovary 5-celled, ovules numerous in each cell on axile placentas; stigmas 1-5, linear to clavate, included or exserted. Fruit becoming red then purple-black, baccate, fleshy to juicy, ellipsoid to ovoid or subglobose, with calyx limb persistent; seeds numerous, small, irregularly angled to lenticular; testa membranous, reticulate.
H. S. Lo (in FRPS 71(1): 388. 1999) described the flower arrangement with short pedicels or subsessile, but the structures interpreted there as pedicels are considered by one of us (C. M. Taylor) and by some other authors to be inflorescence axes and the flowers thus are sessile. Lo described the stipules as multifid or bristlelike, but this condition is not otherwise known from the genus and has not been seen on any Chinese specimens. He gave the number of calyx lobes, corolla lobes, and stamens as 4-6, but this has not been seen; these structures are 5 in all Hamelia species known. The corollas were described as villous in throat, but all known species of Hamelia have corollas that are glabrous inside; as well, the corolla was described as campanulate in shape, but the cultivated species has rather narrowly tubular flowers. The anthers were described as basifixed and entire at base, but other authors all found them dorsifixed and sagittate at base.
Sixteen species: neotropical, from S United States and Mexico to Argentina; one species (introduced) in China.
(Authors: Chen Tao (陈涛); Charlotte M. Taylor)