THAI FOREST BULLETIN (BOTANY) 36
Distribution.— So far known only from eastern and northeastern Thailand but very likely to occur across the Mekong in adjacent Laos as well.
Ecology.— In dry mixed deciduous/dipterocarp forest, in open areas or under low, broken canopy; always reported on sandstone. Altitude from 150–300 m. Flowering: July– October. Fruiting: September–November.
Conservation Status. — Least Concern (LC) (IUCN 2001). Argyreia leucantha is locally common at several sites in Mukdahan and Ubon Ratchathani and may occur elsewhere on suitable sandstone substrates. Based on our current level of field knowledge this seems to be a species of Least Concern.
Etymology.— The epithet, leucantha, refers to the shining white corollas.
Notes.— The oblong-lanceolate leaves of A. leucantha could be confused with A. popahensis or A. lanceolata. The habit, foliage and flowering parts are similar to A. thorelii, but the corolla shape immediately separates the two: salverform and deeply 5-parted in A. thorelii, campanulate and entire to shallowly 10-lobed in A. leucantha. The large, waxy white flowers borne in clusters are very beautiful and this species would make an attractive ornamental climber.
IV. NEW DISTRIBUTION RECORDS
Identification of material in herbaria resulted in the discovery of 13 new distribution records for Convolvulaceae in Thailand, eight in Argyreia, two in Merremia, and one each in Cuscuta, Dichondra, and Ipomoea. These are presented in alphabetical order.
A. Argyreia fulvocymosa C.Y.Wu,Yunnan Trop. Subtrop. Fl. Res. Rep. 1: 135. 1965; R.C. Fang & Staples in C.Y.Wu & Raven, Fl. China 16: 320. 1995; Traiperm, Tax. Study Argyreia Thailand p. 37. 2002.
First record in Thailand. Although mentioned in the recent checklist of Thai Convolvulaceae (Staples et al., 2005) no supporting specimens were cited to document the occurrence or distribution of A. fulvocymosa in Thailand; they are now cited below.
Thailand.— NORTHERN: Phitsanulok [Phu Miang, in light forest, 1200–1650 m, 4 Oct. 1967, Shimizu et al. T-11676 (BKF, L)]; NORTHEASTERN: Phetchabun [Phu Miang, edge of thicket, 1200–1300 m, 2 Oct. 1967, Shimizu et al. T-11320 (BKF, L), same locality, along stream in sunny place, Shimizu et al. T-11321 (BKF, L)]; Loei [vic. Phu Kradueng, edge of evergreen forest, 9 Sept. 1988, Takahashi & Tamura T-63458 (BKF)]; CENTRAL: Nakhon Nayok [Khao Yai National Park, margins of primary evergreen hardwood forest, 725 m, 6 Sept. 2001, Maxwell 01–390 (A, BKF), Wang Chumpi area, roadside in seasonal evergreen forest, 740 m, 20 Feb. 1999, Charoenchai 751 (BKF)].
A sterile collection probably belongs here, based on the leaf and indumentum characters: NORTHEASTERN: Loei [Phu Kradueng National Park, summit of mountain in regrowth of a burned hardwood forest, 2 Dec. 1985, Staples & Wongprasert 382 (A, BKF)].
B.Argyreia hookeri C.B.Clarke in Hook.f., Fl. Brit. India 4: 185. 1883; Ooststr. & Hoogland, Fl. Males. 1(4): 502. 1953; Mill, Fl. Bhutan 7(2): 842. 1999.