Sohmaea diffusa H. Ohashi & K. Ohashi 2018
Creators: name: Saisorn, Witsanu
name: Chantaranothai, Pranom
Publisher: name: Zenodo
Year: 2022
Subjects: Biodiversity
Taxonomy
Plantae
Tracheophyta
Magnoliopsida
Fabales
Fabaceae
Sohmaea
Sohmaea diffusa

description: 1. Sohmaea diffusa (DC. 1825a: 100) H.Ohashi & K.Ohashi (2018b: 161).   
 ≡ Desmodium diffusum DC.   
 Type:— India orient, Lambert s.n. (lectotype G-DC! G00317409, designated by Ohashi & Xiang-Yun, 2005).   
 ≡ Hedysarum diffusum [Roxburgh (1814: 57), nom. nud.] Roxburgh (1832: 357), non Willdenow (1802: 1180), nom. illeg. Type:— India orient, Roxburgh s.n. (syntypes BM, n.v. & BR! BR0000009894365 [digital image]).   
 = Desmodium laxiflorum DC. var. formosense Ohwi (1951: 235). Type:— TAIWAN (Formosa). Fujieda in Kizangun, Okamoto s.n. (holotype KYO, n.v.), fide Ohashi & Zhu (2005).   
 = Desmodium laxiflorum subsp. parvifolium H.Ohashi & T.T.Chen (1983: 268). Type:— TAIWAN. Pingtung Co., Mutan, 350–400 m, 26 Oct. 1982, Ohashi et al. 13486 (holotype TUS, n.v., isotypes TAI, n.v., TI, n.v., TUS, n.v.), fide Ohashi & Zhu (2005).   
 = Desmodium unibotryosum C.Chen & X.J. Cui (1987: 307), nom. illeg.   
 Herb, 10–70 cm high; stems and twigs terete, glabrescent or appressed pubescent. Leaves trifoliolate, rarely unifoliolate on lower part of plant, spirally arranged; stipules triangular, 3–10 × 2–3.5 mm, apex long acuminate, curved or straight, surface glabrescent to puberulous; petioles (0.3–) 1.5–2.5 cm long, appressed pubescent and uncinate; rachis 3–10 mm, appressed pubescent and uncinate. Leaflets: stipels filiform, 1.5–3 mm long, apex pointed, glabrescent; petiolules 1.5–2 mm long, pubescent. Terminal leaflet ±elliptic to obovate, 1.5–6.5 × 1–3.5 cm, apex acute to attenuate, base cuneate to obtuse, margin entire, upper surface sparsely straight and uncinate hairy, lower surface densely pubescent; lateral veins 5–7 per side, prominent. Lateral leaflets ±elliptic to ovate, 1–3.5 × 0.5–2 cm, apex acute, base obtuse, margin entire, both upper and lower surfaces like terminal leaflet; lateral veins 5–7 per side, prominent. Inflorescences 10–20 cm long, terminal at both terminal and lateral shoots; rachis straight and uncinate hairy. Primary bract narrowly ovate, ca. 3 × 0.7 mm, apex long acuminate, margin fimbriate, surface pubescent, distinctly veined, enclosing 4-immature flowers and secondary bract. Secondary bract narrowly ovate, 2–2.8 × 0.3–0.5 mm, margin fimbriate, surface pubescent. Flowers ca. 5 mm long, 4-flowered fascicles; bracteoles absent; pedicels 3–4 mm long, with straight hairs on lower most and densely uncinate hairs toward the upper part of pedicel. Calyx dark brownish red, 2.5–3 mm long, base obtuse; outside pubescent, inside glabrous, tube ca. 1.2 mm long; teeth 1–1.2 mm long, ±equal to tube length, upper tooth shallowly divided, ca. 0.3 mm deep. Corolla: standard light blue, wings and keels white; standard broadly ovate, 5.5–6 × 4–4.5 mm, apex emarginate, base attenuate to cuneate, entire at base, claw 1–1.7 mm long; wings slightly oblong to obovate, 4.5–5 × 1.5–2 mm, apex obtuse to rounded, base auriculate, 0.2–0.4 mm long, claw 0.5–0.8 mm long; keels narrowly curved, 4.5–5 × 1.3–1.5 mm, apex acute to obtuse, base auriculate, ca. 0.2 mm long, claw 1–1.8 mm long. Stamens 4.5–5 mm long; anthers ellipsoid, ca. 0.3 × 0.2 mm. Gynoecium 4.5–5 mm long; ovary oblong, sessile, laterally compressed, with minutely hairs, 6–8-ovulate; style 1.5–2 mm long, glabrescent; stigma minutely capitate. Pods indehiscent, 6–8-articulate, oblong, 3–3.5 × 0.2 cm, surface densely uncinate, smooth, upper and lower sutures repand, equally constricted, less than 0.5 mm deep; isthmus ca. 3/5 as broad as the pod; articles linear-oblong, 4–6 mm long, prominently longer than broad; pod stipe ca. 1.5 mm long, glabrescent; fruiting pedicels 3–4 mm long, pubescent, with straight hairs on lower most and densely uncinate hairs toward the apex. Seeds transversely oblong.   
 Distribution:— India, Nepal, Bhutan, Myanmar, China, Taiwan, Thailand, Indonesia, Philippines, and Papua New Guinea.   
 Ecology:—Open areas of deciduous and bamboo forests; ca. 635 m elev.   
 Phenology:—Flowering in September–October. Fruiting in October–November.   
 Specimens examined:— THAILAND. Chiang Mai: Mae Rim, Doi Suthep, 1 Oct. 1988, Maxwell 88-1161 (CMU, L), Samoeng, Karen village, 11 Oct. 2001, Maxwell 01-522 (CMUB) & Mae Rim, Mae Sa Botanical Garden, 5 Oct. 1989, Pooma 372 (BKF); Nan: Doi Phu Kha, 31 Oct. 2013, Clark et al. 303 (K); LAOS. Houa Phan: Na Ham, Sam Neua, 14 Sept. 1920, Poilane 1851 (AAU, BKF, L, P-2 sheets); Entre N. Dlet et M. Seng Traminh, 800–1000 m, 13 Sept. 1929, Poilane 16940 (P); 240 Km de la route de Vinh au Tanninh, 1500–1600 m, 30 Aug. 1929, Poilane 16790 (P-2 sheets); VIETNAM. Tonkin: Moc Ha, 10 Oct. 1891, Balansa 4493 (P), without locality, Oct. 1887, Balansa 2205 (P), Tonkin Occidental, Bon 6070 (P-2 sheets), Tonkin Occidental, Bon 6071 (P-2 sheets) & Tonkin Occidental, Bon s.n. (G); Hanoi: Nam Cong, 18 Nov. 1891, Bon 4923 (P-4 sheets); Lao Cai: route de Lao Kay à Chapa, 200–1400 m, 25 Sept. 1943, Petelot B. 390 (P-2 sheets) & entre Bao Nhai et Pakha, 500–600 m, 10 Dec. 1935, Poilane 25021 (P-3 sheets); Yen Bai: Bao Ha, 21 Feb. 1936, Poilane 25248 (BKF, P); Hoa Binh: Cho Bo, 15 Nov. 1887, Balansa 2194 (P); Nghe An: Pu Mat, Khe Bu, 17 July 1998, Khoi C 556 (HNU) & Pu Mat, Khe Bu, 17 July 1998, Khoi C 557 (HNU); Ba Ria-Vung Tau: Long Son, Quan Ho, 20 Oct. 1911, Lecomte & Finet 11 (P).
description: Published as part of Saisorn, Witsanu & Chantaranothai, Pranom, 2022, A taxonomic revision of two genera, Pleurolobus and Sohmaea (Leguminosae) in Thailand and Indo-China, pp. 231-246 in Phytotaxa 573 (2) on pages 237-238, DOI: 10.11646/phytotaxa.573.2.4, http://zenodo.org/record/7349951