1. Dentella repens (Linnaeus) J. R. Forster & G. Forster, Char. Gen. Pl. 13. 1775.
小牙草 xiao ya cao
Oldenlandia repens Linnaeus, Syst. Nat., ed. 12, 2: 126; Mant. Pl. 1: 40. 1767; Dentella matsudae Hayata; D. repens var. grandis Pierre ex Pitard.
Dwarf herbs, creeping, much branched, rather fleshy; branches flattened to angled, glabrous or puberulent, often rooting at nodes. Leaves subsessile to shortly petiolate; petiole to 1[-4] mm; blade drying stiffly papery, oblong-lanceolate, oblanceolate, or spatulate, 4-7[-10] × 1-2[-4] mm, glabrous or sparsely hirtellous at least along margins and principal veins, base cuneate to acute, margins flat, apex obtuse to acute; secondary veins not visible; stipules triangular, ca. 1 mm, entire to erose. Flowers solitary at forks of branchlets or rarely along stems, subsessile or with pedicel to 1[-2] mm. Calyx with ovary portion subglobose, ca. 1 × 1-1.5 mm, densely papillose-villous with flattened trichomes; limb 1-1.2 mm, deeply lobed; lobes narrowly triangular. Corolla white or pale yellow, 3-8[-12] mm, glabrous outside, sparsely villous inside throat; lobes triangular-ovate, 1-2 mm, acute. Fruit compressed globose, 3-5 × 3-5 mm, densely villous with multicellular, transparent, flattened, bulbous-tipped trichomes; seeds 0.3-0.5 mm. Fl. winter, fr. summer.
Wet sites in fields; sea level or higher. Guangdong, Hainan, Taiwan, Yunnan (Xishuangbanna) [India, Indonesia, Malaysia, Myanmar, Nepal, Philippines, Sri Lanka, Thailand, Vietnam; Australia, Oceania; adventive in North America (E United States, Mexico)].
The Fl. Taiwan (ed. 2, 4: 252. 1998) described markedly larger leaves, petioles, pedicels, and corollas than seen on specimens studied for this work or found in other descriptions; these measurements are included above provisionally in brackets. Two varieties were recognized by Xing and Wu (Fl. Nansha Islands, 200-201. 1996): Dentella repens var. repens, with flowers ca. 3 mm, and D. repens var. grandis, with flowers 6-8 mm; their description of the second variety corresponds to the larger flower measurements given in Fl. Taiwan. These varieties were subsequently synonymized by H. S. Lo (in FRPS 71(1): 21. 1999) and are provisionally synonymized here.