Crotalaria dubia Graham ex Bentham (1843: 568)

Ninkaew, Sakuntala, Balslev, Henrik, Pornpongrungrueng, Pimwadee & Chantaranothai, Pranom, 2017, Crotalaria L. (Fabaceae: Faboideae) in continental Southeast Asia, Phytotaxa 320 (1), pp. 448-450 : 448-450

12. Crotalaria dubia Graham ex Bentham (1843: 568) . Type (lectotype designated by Ansari 2008):— INDIA. East India, without exact location; probably Sylhet or Burma, Wallich 5404 (lectotype K000591064!).

Herb, erect, 30–50 cm high; young branches terete, brown pubescent. Leaves simple. Stipules narrowly linear, 2–4 mm long, brown pubescent, caducous. Petioles 2–4 mm long, brown pubescent. Lamina obovate or elliptic, 1.2–5.5 × 0.4–3 cm, base cuneate, apex rounded or obtuse, margin entire, both surfaces brown pubescent; lateral veins 5–6 pairs. Inflorescences terminal or axillary, open very dense racemes, 1–5 cm long; peduncle 3–7 mm long, densely brown pubescent. Bracts ovate, 4–7 × 2–3 mm, persistent. Pedicels 1–2 mm long, brown pubescent. Bracteoles inserted distally on the pedicel, ovate, 3–5 × 2–3 mm, persistent. Calyx 6–8 mm long, campanulate, bilabiate; tube 1–2 mm long; lobes triangular, 4–5 × 0.8–1.2 mm, glabrous above, brown pubescent outside. Corolla yellow. Standard: claw 1–1.5 mm long, white tomentose above and along the margin, glabrous below; blade broadly ovate, 4.5–5 × 3–3.5 mm, base cuneate, apex obtuse, margin glabrous. Wings: claw 1–1.2 mm long, glabrous; blade lanceolate, 3.5–5 × 1–1.3 mm, base oblique, apex attenuate, margin glabrous. Keel: claw 1–1.2 mm long, glabrous; blade ovate, 4.5–5 × 2.3–2.5 mm, beak spirally twisted, base cuneate with white pubescence, apex attenuate, margin glabrous. Stamens: filaments fused for proximal 2–2.3 mm, free for distal 1.5–2.3 mm; anthers either narrowly linear, ca. 1 mm long or elliptic, ca. 0.2 mm long. Ovary sessile, elliptic or oblong, 1.4–1.6 mm long, glabrous; style 4.5–5 mm long, adaxially densely white pubescent in a single line along the distal edge, abaxially glabrous. Pods sessile, oblong, 5–7 × 2.5–3 mm, brown-black, glabrous. Seeds harp-shaped, 1–1.5 × 1.6–1.8 mm, yellow-brown.

Representative specimens: — MYANMAR. Chin State: along the roadside between Saw and Mindat, Natma Taung National Park , 1 March 2013, Sangvirotjanaphat 91167 ( QBG) . THAILAND: Chiang Mai: Doi Chiang Dao Wildlife Sanctuary , 20 December 2014, Ninkaew 307 ( KKU) . Chiang Rai: Khun Chae National Park , 30 December 1997, Maxwell 97-1544 ( CMUB) . Nan: Bo Kluea , 21 February 2014, Ninkaew 252 ( KKU) . Phrae: Mae Kham Mi , 5 January 1972, Beusekom et al. 4646 ( BKF) . VIETNAM. Gia Lai: Dak Doa , 28 October 1978, Loc & Nghia P 3711 ( HNU) .

Distribution: —Asia ( India, China, Thailand, Vietnam). ( Figure 9 ).

Ecology: —Roadsides, elevation 160–900 m.

Notes: — Crotalaria dubia is distinct from all other species of Crotalaria in having dense open inflorescences with ovate bracts, wings with attenuate apex and the keel with glabrous margins.

Figures

FIGURE 9. Distribution map of Crotalaria dubia, C. evolvuloides and C. filiformis in continental Southeast Asia.