16. Galium exile J. D. Hooker, Fl. Brit. India. 3: 207. 1881.
单花拉拉藤 dan hua la la teng
Galium handelii Cufodontis (1940), non Nábělek (1923).
Herbs, annual, slender, procumbent to weak, 4-20 cm tall. Roots slender, reddish when dry. Stems slender, 4-angled, somewhat branched, sparsely retrorsely aculeolate to glabrous. Middle stem leaves opposite with clearly smaller, leaflike stipules in whorls of 4; blades drying papery, obovate or oblanceolate to linear-elliptic, (2-)3.5-10(-12) × 1-3.5(-5) mm, adaxially with sparse appressed hairs or glabrous, margins mostly antrorsely ciliolate, otherwise glabrous, base acute, cuneate, or shortly petiolate, apex obtuse to acute but not mucronate; principal vein 1, with inconspicuous pinnate-reticulate lateral veins. Flowers mostly solitary; pedicels 1-3 mm, glabrous. Ovary subglobose, ca. 1 mm, densely covered with undeveloped trichomes. Corolla white, rotate, 1-1.5 mm in diam.; lobes 3(or 4), ovate, obtuse. Mericarps ovoid to elongated, 2-2.5 mm, with dense, white to yellowish brown, uncinate trichomes 0.2-0.5 mm, on pedicels elongating to 10 mm and curved near apex. Fl. Jun-Jul, fr. Aug-Sep.
Rock crevices on mountain slopes, sand and gravel drifts on grassy plains; 1200-4800 m. Gansu, Nei Mongol, Ningxia, Qinghai, Shaanxi, Shanxi, Sichuan, Xinjiang, Xizang, Yunnan [India, Nepal].
In his description of Galium handelii Cufodontis (Oesterr. Bot. Z. 89: 234-235. 1940) referred to the close G. songaricum Schrenk (in Fischer & C. A. Meyer, Enum. Pl. Nov. 1: 57. 1841) but overlooked the older homonym by Nábělek and the Himalayan G. exile. This latter annual has a much wider distribution than thought before and is quite variable in China with respect to leaf shape and hairiness, length of pedicels, shape of mericarps, etc. In view of its remarkably small flowers and high fruit set, it very likely is autogamous.
Within the morphologically and DNA-analytically very isolated Galium sect. Depauperata (Ehrendorfer et al., Fl. Iranica 176: 231-232. 2005) G. exile is morphologically very close to the W North American G. bifolium S. Watson and particularly to G. songaricum, described from the C Asiatic mountain system of Alatau. This latter species, treated in FRPS as "G. soongoricum," is assumed to differ by its 1- or 2(or 3)-flowered cymes, the 4-lobed flowers, and the strongly elongating fruiting pedicels. In FRPS (71(2): 224-227. 1999) both taxa are accepted and indicated for very much the same area in China. Nevertheless, a first analysis of all Chinese specimens in PE, KUN, MO, and WU has not revealed reliable differential characters. Even the inflorescence character and the corolla lobe number varies in some specimens. All these findings do not exclude the possibility that further and more detailed studies will allow to separate the populations from the mountains of C and N Asia as typical G. songaricum. But for the Chinese flora and the present treatment we recognize only one species, G. exile. In case that the two taxa cannot be separated as species in the future G. songaricum will have to replace G. exile for priority reasons.
As noted already by Cufodontis (loc. cit.), both Galium exile and G. songaricum have sometimes been misidentified as G. pauciflorum, a synonym of G. spurium from the G. aparine group. In contrast to G. exile, the latter always has more than 4 leaf whorl elements, retrorsely aculeolate leaf margins, and more than 1-flowered cymes.