46. Leptunis Steven, Bull. Soc. Imp. Naturalistes Moscou. 29(2): 366. 1857.
乐土草属 le tu cao shu
Authors: Tao Chen & Friedrich Ehrendorfer
Herbs, annual, slender. Raphides present. Stems subterete. Leaves and leaflike stipules in whorls of 8-16, sessile, linear to filiform, without domatia. Inflorescences terminal, thyrsoid, below with dichasial and above with monochasial cymes, few flowered when young but usually continuing to grow and becoming many flowered and diffuse; peduncles and pedicels filiform with leaflike bracts and reduced bracteoles. Flowers pedicellate to sessile, bisexual, monomorphic. Calyx limb obsolete. Corolla salmon-orange to pale greenish, tubular to funnelform, glabrous inside; lobes 4, valvate in bud. Stamens 4, inserted in upper part of corolla tube, included or partially exserted; filaments short; anthers dorsifixed, black. Ovary inferior, 2-celled, ovules 1 in each cell, basal; stigmas 2, globose, partially exserted. Fruit schizocarpous; mericarps obovoid, with 1 seed, indehiscent, upper part somewhat incurved, dry, with appressed short and curved hairs.
One species: from the SE Caucasus through Afghanistan and C Asia to NW China.
Ehrendorfer et al. (Fl. Iranica 176: 1-287. 2005) included the monotypic genus Leptunis in Asperula sect. Trichodes Boissier, based on the following arguments. Segregation of Leptunis as a monotypic genus from Asperula was based only on its ripe mericarps being rather obovoid and incurved than ellipsoid and straight. Furthermore, Leptunis appears closely linked to Asperula by A. seticornis Boissier. This local species from S Iran has long been recognized as having fruit that are intermediate in shape between Leptunis and "typical" Asperula. Nevertheless, considering the still incomplete DNA-analytical study of SW-Asiatic taxa of Asperula and the recent discovery of Leptunis in China (Abdusalih et al., Acta Bot. Boreal.-Occid. Sin. 23(4): 674. 2003), the genus is provisionally retained here. It is inserted in the key to Rubieae genera and species found in the present volume under Galium.