Pleurolobus flexuosus (Wallich 1831: 195 ex Bentham 1852: 224 ) H.Ohashi & K. Ohashi (2018c: 386)

Saisorn, Witsanu & Chantaranothai, Pranom, 2022, A taxonomic revision of two genera, Pleurolobus and Sohmaea (Leguminosae) in Thailand and Indo-China, Phytotaxa 573 (2), pp. 231-246 : 232-233

1. Pleurolobus flexuosus (Wallich 1831: 195 ex Bentham 1852: 224) H.Ohashi & K. Ohashi (2018c: 386) .

≡ Desmodium flexuosum Wall. ex Benth.

Type:— MYANMAR. Montes Prome, 1826, Wallich 5691 (lectotype K-W! K001121777 , designated here, isolectotypes G!-2 sheets, BM!, K! K000858866, CAL, n.v.) .

≡ Meibomia flexuosa (Wall. ex Benth.) Kuntze (1891: 198) .

Creeping herb; stems and twigs angular or subterete, brown pubescent. Leaves subalternately or spirally arranged; stipules, narrowly triangular, 5–10 × 1–1.5 mm, apex acuminate, surface long pubescent; petioles (0.3–) 1.5–3.5 cm long, densely erect pubescent. Leaflet coriaceous; stipels narrowly triangular to filiform, 2–5 mm long, apex pointed, surface glabrescent to pubescent; petiolules 1–3 mm, densely pubescent; leaf blade cordate, broadly obovate to broadly elliptic, 1.5–6.5 × 1.5–6 cm, apex ±acute to rounded or shallowly emarginate, base ±cordate, margin entire, upper surface glabrescent, lower surface appressed pubescent, denser than upper surface; lateral veins 7–9 per side. Inflorescences pseudoracemose or paniculate, with a few branches, 5–15 cm long; rachis and rachilla densely pubescent and minutely uncinate. Primary bract 3–7 × 0.5 mm, apex pointed, surface long pubescent, enclosing 2-immature flowers and secondary bract. Secondary bract persistent, narrowly triangular, ca. 1 × 0.3 mm, pubescent. Flowers 2–2.5 mm long, 2-flowered fascicles; pedicels 2–2.5 mm long, with uncinate hairs. Calyx 1.5–2 mm long, base obtuse; outside white pubescent, tube ca. 1 mm long; teeth 4, 0.8–1 mm long, ±equal to tube length, upper tooth shallowly divided, less than 0.2 mm long. Corolla : standard broadly obovate, ca. 3 × 3 mm, apex shallowly emarginate, base attenuate, entire or slightly auriculate at base, claw very short; wings ca. 3 × 1.2 mm, ±equal to the keel petals, apex obtuse, base not auriculate, claw ca. 0.5 mm long; keels curved, ca. 3.2 × 1.5 mm, the broadest part near the apex, apex obtuse, base not auriculate, claw ca. 1.5 mm long. Stamens ca. 3 mm long. Gynoecium ca. 3.5 mm long; ovary appressed pubescent; style ca. 1.5 mm long, glabrescent; stigma minutely capitate. Pods dark brown to black, 3–4-articulate, straight, 7–10 × 2–2.5 mm, surface sparsely uncinate, inconspicuously reticulate-patterned, upper suture undulate, lower suture more constricted than upper suture, ca. 1 mm deep; isthmus 2/5 as broad as the pod; articles obliquely ovate or subcircular, ca. 3 mm long; pod usually sessile or shortly stipitate, ca. 0.5 mm long; fruiting pedicels 2.5–3 mm long, with uncinate hairs. Seeds transversely elliptic.

Distribution:— Myanmar, Thailand, and Cambodia.

Ecology:—In teak plantation, with bamboo and deciduous forests; 30–400 m elev.

Phenology:—Flowering in November. Fruiting in November–February.

Notes:— Two specimens, Maxwell 06-874 (CMUB) and Pierre 1006 (P) are newly recorded for Cambodia. Desmodium flexuosum Wall. ex Benth. was validly published. Five original specimens were examined at BM, G, K, and K-W by authors and one duplicate was recorded by Ohashi (1973). All specimens are from the same gathering and in a perfect condition. A specimen kept at K-W ( K001121777 ) is selected here as the lectotype because it is well preserved in Wallich’s collection at Kew.

Specimens examined:— THAILAND. Chiang Mai: Doi Suthep, 1100 m, 17 Oct. 1910, Kerr 1480 ( ABD, BM, C, K-2 sheets, L, P), Doi Suthep, 1200 m, 28 Nov. 1911, Kerr 1480B ( BM, E, K, L, P) & Doi Suthep-Pui National Park , 350 m, 19 Dec. 1989, Maxwell 89-1568 ( CMU, E, L) ; Lampang: Chae Son, Ban Sa , 400 m, 7 Nov. 2008, Maxwell 08-198 ( CMUB) ; CAMBODIA. Kratie: Sambour, Mekong River , 30 m, 15 Nov. 2006, Maxwell 06-874 ( CMUB) & May 1870, Pierre 1006 ( G, P) .