36. Crotalaria retusa Linnaeus (1753: 715). Type (lectotype designated by Niyomdham 1978):— SRI LANKA. Hermann 2: 21, No. 276 (lectotype BM000594584).

Herb, erect, 0.5–1 m high; young branches angular, white pubescent. Leaves simple. Stipules narrowly linear, 0.5–1 mm long, persistent. Petioles 1–3 mm long, brown pubescent. Lamina obovate, 2.3–6 × 0.2–2.5 cm, base cuneate, apex rounded or acute, margin entire, glabrous upper, white pubescent lower; lateral veins 6–11 pairs. Inflorescences terminal, open racemes, 10–18 cm long; peduncle 4.5–5 cm long, white pubescent. Bracts narrowly linear, 2–3 mm long, persistent. Pedicels 3–5 mm long, brown pubescent. Bracteoles inserted on the pedicel, narrowly linear, 0.5–1 mm long, persistent. Calyx 1–1.5 cm long, campanulate, bilabiate; tube 5–7 mm long; lobes triangular, 5–8 mm long, glabrous inside, white puberulous outside. Corolla yellow. Standard: claw 3–3.5 mm long, white tomentose above and along the margin, glabrous below, apex with appendages; blade orbicular, 18–23 × 18–23 mm, base rounded, apex rounded, margin glabrous. Wings: claw 3–4 mm long, white tomentose above and along the margin, glabrous below; blade oblong, 14–15 × 7–8 mm, base oblique white tomentose, apex obtuse, margin glabrous. Keel: claw 3–4 mm long, glabrous, margin white tomentose; blade ovate, 12–14 × 8–9 mm, beak spirally twisted, base oblique, apex attenuate, margin white tomentose. Stamens: filaments fused for proximal 7–8 mm, free for distal 5–7 mm; anthers either narrowly linear, 2.5–3 mm long or elliptic, 0.8–1 mm long. Ovary with 2–2.5 mm long stipe, oblong, 5–7 mm long, glabrous; style 12–15 mm long, adaxially and abaxially white pubescent in two lines along the edges. Pods with 4–5 mm long stipe, obovate, 4–5.2 × 0.8–1 cm, brown, glabrous. Seeds reniform, 4–5 × 3–4 mm, black-brown.

Representative specimens: — CAMBODIA. Banteay Meanchey: Thma Puok, 24 October 1927, Poilane 14382 (P). LAOS. Savannakhet: 13 October 1938, Poilane 28043 (L, P). MYANMAR: No locality, 1891, Huk 59 (L). SINGAPORE: Changi, 1890, Ridley 2087 (SING). Istana, 15 April 2002, Ahmad SA 44 (SING). Sembawang, Lentor Avenue, 29 May 2003, Lee et al. LA28 (SING). THAILAND. Buriram: 26 November 1976, Phengklai et al. 3450 (BKF). Chon Buri: 26 August 1997, Anon. s.n. (BCU). Chumphon: Hat Sai Ri, 16 February 1968, Vacharapong 46 (BK). Mae Hong Son: Mueang, 13 December 2007, Tanaka et al. HN8322 (QBG). Nakhon Ratchasima: Pak Thong Chai, 2 November 1969, Beusekom & Charoenphol 2027 (AAU, BKF). Prachuap Khiri Khan: Pa Klang Ao Forest Park, 4 June 1995, Jonganurak 346 (BCU). Sakon Nakhon: Phu Phan National Park, 12 November 2013, Ninkaew 295 (KKU). Si Sa Ket: Uthumphon Phisai, 7 October 1984, Murata et al. T-37792 (AAU, BKF). Surin: Sangkha, 6 October 1984, Murata et al. T-37665 (BKF). Ubon Ratchathani: Warin Chamrap, Ban Bung Malaeng, 1 October 1985, Paisooksantivatana y1612-85 (BK). VIETNAM. Bac Giang: Viet Yen, 10 October 1909, Bacche 73 (P). Khanh Hoa: Nha Trang, 23 April 1932, Poilane 6052 (K, L, P). Lam Dong: Da Lat, 9 March 1911, Lecomte & Finet 1498 (P). Nihn Thuan: Phan Rang-Thap Cham, Cana, 28 September 1940, Poilane 30629 (HN, K, L, P). Thanh Hoa: August 1923, Petelot 1029 (K, P).

Distribution: —North America, Africa, Asia (Maldive Islands, India, Sri Lanka, Myanmar, China, Taiwan, Thailand, Laos, Cambodia, Vietnam, Singapore), Australia, Hawaii. (Figure 22).

Ecology: —Open places in deciduous dipterocarp forests, elevation 4–1500 m.

Notes: — Crotalaria retusa has often been confused with C. assamica, but differs by having narrowly linear bracts and persistent bracteoles.