8. Diarthron Turczaninow, Bull. Soc. Imp. Naturalistes Moscou. 5: 204. 1832.
草瑞香属 cao rui xiang shu
Authors: Yinzheng Wang & Michael G. Gilbert
Annual or perennial herbs, or small deciduous shrubs. Leaves alternate; leaf blade elliptic, linear, or lanceolate, herbaceous. Inflorescence usually terminal, sometimes apparently axillary, laxly racemose to capitate, without involucre. Flowers bisexual, small, 4(or 5)-merous. Calyx reddish, white, or green; tube persistent, slender, urceolate, funnel-shaped, or cylindric, contracted and articulate at apex of ovary; lobes 4, erect and slightly spreading. Petaloid appendages absent. Stamens as many as or twice as many as calyx lobes, in one or two series, opposite to calyx lobes when in one series; filaments absent; anthers oblong, included. Disk annular, oblique, sometimes tiny or absent. Ovary ± stipitate, glabrous, 1-loculed; style excentric or subterminal, short; stigma subclavate, thick. Fruit dry, enclosed by persistent calyx base; pericarp thin, glossy black.
Sixteen species: C and SW Asia, SE Europe (European Russia); four species in China.
The authors have accepted the view of Kit Tan (Notes Roy. Bot. Gard. Edinburgh 40: 219-220. 1982) that the difference in habit used to separate the annual herbs of Diarthron sensu stricto from the perennial herbs traditionally placed in Stelleropsis and the small shrubs in the C Asian genus Dendrostellera (C. A. Meyer) Tieghem are outweighed by the similar 4-merous flowers and ebracteate inflorescences combined with the continuous range of variation in habit.