e-Flora of Thailand
Volume 15 > Part 1 > Year 2021 > Page 168 > Rubiaceae > Argostemma
6. Argostemma elatostemma Hook.f.wfo-0000265249
Fl. Brit. India 3: 45. 1880; Ridl., Fl. Malay Penins. 2: 27. 1923; Craib, Fl. Siam. 2: 28. 1932; Sridith, Thai Forest Bull., Bot. 27: 92, fig. 4. 1999.
Accepted Name : This is currently accepted.
Synonyms & Citations :
Description : Perennial herbs 5–23 cm long, with underground rhizome; stems creeping, unbranched or occasionally slightly branched; internodes of rather equal length, 0.6–3 cm; adventitious roots at nodes on lower part of stem, densely covered with short fine hairs. Stipules ovate, 3–5 by 1.5–3 mm, tip entire or occasionally bifid, glabrous or margin pubescent. Leaves opposite, in many pairs scattered along stem, distichous, strongly anisophyllous; blades elliptic or ovate, 3.5–6 by 1.7–4 cm (large leaves) or 0.3–1 by 0.2–0.6 mm (small leaves), base conspicuously auriculate-oblique (very unequal-sided), apex obtuse, round or (less often) acute, chartaceous, discolorous (dark green above, greyish or whitish beneath), sparsely pubescent above, densely covered with short fine hairs along midrib and veins beneath, midrib with several pairs of ascending lateral veins, both conspicuous and raised beneath; petiole 2–8 mm long or subobsolete (small leaves), densely covered with short fine hairs. Inflorescences 5–12-flowered, ± dense compound cymes; peduncles 0.5–3 cm long, densely covered with short fine hairs; bracts free, anisophyllous, linear-lanceolate, 2–3 by 0.5 mm, green, pubescent; pedicels 4–8 mm long, densely covered with short fine hairs. Flowers 5-merous, slightly zygomorphic. Calyx chartaceous, green; lobes triangular, 1–1.5 by 1–1.5 mm, suberect, densely covered with short fine hairs. Corolla star-shaped, sparsely pubescent outside; tube 0.5–1 by 1.5 mm; lobes narrowly triangular or lanceolate, 7–8 by 2.5–3 mm, spreading. Stamens 5; filaments free, < 1 mm long; anthers coherent into an occasionally curved anther cone, pale yellow, 7–8 mm long, semibasifixed, oblong, apical appendages ca 1 mm, opening by longitudinal slits. Ovary ca 1.5 mm, pubescent; style filiform, 8–9 mm long, shortly exserted from anther cone (ca 1 mm), glabrous; stigma capitate. Fruits obconic, ca 2 mm high, glabrous.
Thailand : PENINSULAR: Phatthalung, Trang, Satun.
Distribution : Peninsular Malaysia (Penang, lectotype), Singapore (syntype), Borneo.
Ecology : On wet soil in evergreen forests, 75–1,400 m alt. alt. Flowering: March–June.