Impatiens trilobata Colebr.

Smets, E. F. & Janssens, S. B., 2018, Balsaminaceae of Myanmar, Blumea 63 (3), pp. 199-267 : 247-248

51. Impatiens trilobata Colebr. — Map 17

Impatiens trilobata Colebr. in Hook.f.(1824) 141; D.Dietr.(1839) 846;Hook.f. & Thomson (1860) 126;Hook.f.(1875) 451. — Type: Hooker (1824) t. 141 (lecto, designated in Karthigeyan & Gogoi (2016): Illustration of Colebrooke), Silhet.

Terrestrial, annual herb, 30–60 cm tall. Stem erect, rarely decumbent, unbranched to moderately branched, glabrous to pilose towards apex. Leaves decussate. Petiole (2–)5–15(–40) mm long, glabrous to pilose. Lamina (34–)60–75(–100) by (14–)25–30(–34) mm, ovate to elliptic to narrowly elliptic, apex acute to acuminate, base cuneate to attenuate, margin slightly crenate, adaxial glabrous to remotely pilose, abaxially pilose on the midrib and veins, with 2 or 3 stipular glands on each side of the petiole base; lateral veins (5–)7–9(–11) pairs. Inflorescence axillary, erect, (1–)2–4(–5)-flowered raceme. Peduncle (15–)20–40(–55) mm long, glabrous. Rachis 3–5 mm long. Flowers (14–)20–25(–30) mm long, (15–)20–27(–30) mm deep, pink. Bracts c. 3 by 1 mm, lanceolate, apex acute, base cuneate, margin entire, glabrous to pilose, persistent. Pedicel 10–15 mm long, glabrous. Lateral sepals 2, 3–6 by 1.5–2 mm, free, ovate to elliptic, apex acuminate and mucronate, base cuneate, glabrous to pilose. Lower sepal 14–15(–19) mm long, (18–)20–22(–25) mm deep, saccate, apex acuminate and mucronate, pilose when young, remotely pilose in mature flower, dorsal part rapidly constricted into an incurved hooked to circular spur, 8–12(–15) mm long, sometimes swollen. Dorsal petal (8–)11–12 by (13–) 16–17 mm, broadly elliptic to broadly obovate, cucullate, apex round to cordate, base round to obtuse to cordate, pink, glabrous to pilose near the midrib, abaxial midvein with a keel-shaped crest, 2–3 mm wide. Lateral united petals (24–) 27–29 mm long, free: the upper petals 9–14 by 6–9 mm, orbicular to obovate, apex round to obtuse, base cuneate, pink; the lower petals (15–)17–20 by (8–) 11–15 mm, free, ovate to elliptic to orbicular to obovate, apex round, slightly emarginate inside, base auricled, 2–3 mm wide, pink, glabrous. Stamens: filaments 5–6 mm long. Ovary c. 4 mm long, 1 mm diam, glabrous. Fruits 15–17 mm long, 5 mm diam, fusiform, glabrous. Seeds 2 mm long.

Phenology — Flowering: June to November; fruiting: July to November.

Distribution — Myanmar (Chin State, Kachin State, Mandalay Region, Sagaing Division), Bangladesh (Sylhet Division), India (Arunachal Pradesh State, Assam State, Sikkim State, West Bengal State).

Ecology — Growing in semi-evergreen forest, along the stream, 600–1200 m altitude.

Other collections examined. MYANMAR, Chin State, Ling Shein Mang 093093 (QBG QBG70782), around Kyat Chan village, Kanpetlet, Natma Taung National Park, alt. 1700 m, 13 July 2013; Kachin State, Buchanan s.n. (K), Myitkyina district, Namma Hopii Valley, 450 ft, Oct. 1909; Buchanan 1 (K H2015/00092 135), Myitkyina district, Trinton, alt. 450 ft, 30 Nov. 1910; Buchanan s.n. (E E00752744), ibid., Oct.1909; Murata , Kobayashi, Hayami & Takashima 040847 (QBG QBG61254), west of Lamon Village, 4 miles north of Tanaing, N26°25'28" E96°41'37", alt. 195–200 m, 2 Dec. 2005; Mandalay Region, F.S. (RANG5097), Kadu, 7 Jan. 1960; Anonymous s.n. (RANG011269), ibid., Sagaing division; Buchanan 2 (K), Kale district, Nam- maw village, 18 Oct. 1908; Lace 5526 (E E00752745,K H2015/00092 134), Katha district, Bilumyo Reserve, 800 ft, 9 Nov. 1911.

Note — Impatiens trilobata can be easily distinguished by its decussate leaves, long peduncles, and saccate lower sepal. Impatiens trilobata is similar to I. tripetala but differs in having a longer peduncle.