58. Myrioneuron R. Brown ex Bentham & J. D. Hooker, Gen. Pl. 2: 69. 1873.
密脉木属 mi mai mu shu
Authors: Tao Chen & Charlotte M. Taylor
Small shrubs, subshrubs, or large herbs, unarmed, often succulent; bark often soft or spongy, usually grayish white. Raphides absent. Leaves opposite, apparently without domatia, sometimes with crisped margins; stipules persistent or deciduous, interpetiolar, generally triangular, often closely densely parallel- to palmately veined, entire or shortly bilobed. Inflorescences terminal and/or pseudoaxillary, laxly cymose or usually congested-cymose to subcapitate, several to many flowered, sessile to pedunculate, bracteate with bracts usually well developed, often densely veined to stipuliform, sometimes outermost (i.e., basalmost) 4 or 6 bracts shortly fused at base into an involucre. Flowers sessile to pedicellate, bisexual, distylous. Calyx limb 5-lobed; lobes often densely parallel-veined. Corolla white or yellow, tubular to salverform, villous in throat; lobes 5, valvate in bud. Stamens 5, inserted in corolla tube, included or perhaps partially exserted; filaments short; anthers apparently dorsifixed, included. Ovary 2-celled, ovules numerous in each cell on presumably axile placentas; stigma 2-lobed with lobes linear, included or shortly exserted. Fruit white, baccate, fleshy to rather dry, ovoid to globose, with calyx limb persistent; seeds numerous, small, angled, with endosperm fleshy; embryo small; testa areolate.
About 14 species: Bhutan, China, India, Nepal, Vietnam; four species (one endemic) in China.
H. S. Lo (in FRPS 71(1): 309. 1999) described the inflorescences as sometimes axillary, but this has not been noted elsewhere; the term here may be used to include the position separated elsewhere as "pseudoaxillary." Lo also reported that the anthers are sometimes partially exserted in long-styled flowers of Myrioneuron faberi and M. effusum (loc. cit.: 310, 313), which is a new condition not previously noted for the genus.
The number of pairs of lateral leaf veins described by H. S. Lo (loc. cit.: 310-313) for Myrioneuron species and used in part to distinguish species does not correspond to the secondary veins on specimens cited and apparently includes both secondary and intersecondary veins; thus, the counts disagree with those of Wright (Fl. Bhutan 2(2): 786. 1999, M. nutans) and the illustrations of Fu and Hong (Higher Pl. China 10: 577-578. 2004), which consider only the secondary veins as done by most Rubiaceae authors.