Volume 15 > Part 1 > Year 2021 > Page 141 > Rubiaceae > Spermacoce

3. Spermacoce latifolia Aubl.wfo-0000312527

Hist. Pl. Guiane 1: 55 1775; Ridsdale in Dassan., Revis. Handb. Fl. Ceylon 12: 335. 1998; Wiersema et al., Castanea 82: 114–131. 2017; Harwood in K.M.Wong et al., Fl. Singapore 13: 294, fig. 74C. 2019.— Borreria latifolia (Aubl.) K.Schum. in Martius et al. (eds), Fl. Bras. 6(6): 61, t. 80. 1888; Ridl., Fl. Malay Penins. 2: 175. 1923.

Accepted Name : This is currently accepted.

Synonyms & Citations :

Description : Annual herbs, prostrate or spreading. Leaves ovate, elliptic, or ovate lanceolate, 2–7.5 by 1–3.5 cm, base acute to attenuate, apex acute to acuminate, margin glabrous, charteceous, relatively densely hairy on both surfaces, lateral veins 4–6 pairs, ascending, conspicuously raised on lower surface. Inflorescences terminal and axillary, many-flowered, glomerules hemispheric, 0.7–1.9 cm diam.; bracts leaf-like, 2–7.5 cm long, acute. Calyx lobes 4, green, triangular, to 1.8 mm long, pubescent to hispid outside. Corolla white or mauve, 3–4 mm long; tube to 3 mm long, glabrous except for a band of moniliform hairs inside near the middle; lobes to 1 mm long, outside glabrous or occasional hair near apex, inside usually some scattered hairs. Stamens exserted from corolla tube, not exceeding corolla lobes; filaments 0.8–1.5 mm long; anthers to 0.5 mm long. Style equal to or exceeding corolla lobes, divided at top into 2 short linear stigmas. Capsules obovoid, to 3.5 by 3 mm, hairs mostly restricted to upper half, part of septum lamellae remaining attached to valves at dehiscence. Seeds brown, obovate or elliptic, to 3 by 1.8 mm; relatively hollow, ventral groove deep and extending under seed-coat margin; seed surface dorsally reticulate.

Thailand : NORTHERN: Chiang Mai, Chiang Rai, Nan, Tak, Phitsanulok; SOUTH-WESTERN: Kanchanaburi; CENTRAL: Nakhon Nayok, Krung Thep Maha Nakhon (Bangkok); SOUTH-EASTERN: Prachinburi, Rayong, Chanthaburi, Trat; PENINSULAR: Ranong, Phangnga, Songkhla, Pattani, Narathiwat.

Distribution : Tropical America (Mexico to Paraguay, type from French Guiana); naturalized throughout the tropics of Africa, Asia and Oceania.

Ecology : Common in wetter parts of open disturbed areas, plantations, but also collected from open mixed deciduous and dry evergreen forests, sea level to 1,500 m alt. Flowering and fruiting: July–January.

Vernacular : Kradum bai yai (กระดุมใบใหญ่)(Peninsular).

Notes: Spermacoce latifolia Aubl. has sometimes been synonymized with S. alata (under the latter name), but recent studies (e.g. Wiersema et al., 2017) confirm they are indeed two different species. Spermacoce alata is restricted to the South-American Amazon region and is not weedy, while S. latifolia is very widespread in the Americas, and only this is the pantropical weed. The Thai plants agree well with S. latifolia.