Impatiens tripetala Roxb. ex DC.

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

50. Impatiens tripetala Roxb. ex DC. — Map 17; Plate 4c

Impatiens tripetala Roxb. ex DC. (1824) 687. — Impatiens tripetala Roxb. (1814) 18, nom. nud.; Wall . (1824) 453; G. Don (1831) 750; Roxb. (1832) 651;Hook.f.(1904a) 25,27,31; W.J. Kress et al.(2003) 170. — Type: s. coll. (lecto, designated in Karthigeyan & Gogoi (2016) G G00218033*), India, 1818.

Impatiens multiflora Wall. ex Hook.f. & Thomson (1860) 126. — Impatiens multiflora Wall.(1831) 168,nom.nud.,syn.in Hooker (1904a) 25,31.— Type: De Silva, Wallich Cat . no. 4742 (lecto, designated here K K001039802), Bangladesh, Pundua.

Impatiens ternifolia Buch.-Ham. ex Hook.f. & Thomson (1860) 126, nom. nud. — Impatiens ternifolia Buch.-Ham. in Hook.f. (1904a) 27, nom. nud., syn. in Hooker (1904a) 27, 31. — Based on: Hb. Ham., Wall . Cat . 4752B (K K001039802), India, Assam State, Goalpara, 8 May 1862.

Terrestrial, annual herb, up to 40 cm tall. Stem erect, more than 4 mm diam, unbranched, pilose towards apex. Leaves subopposite to spirally arranged. Petiole 20–60 mm long, 1.5–2 mm diam, glabrous to remotely pilose. Lamina 80–145 by 25–45 mm, elliptic to ovate to lanceolate, apex acuminate, base

Map 17 Distribution of Impatiens rangoonensis Hook.f. (●), I. tavoyana Benth. ex Hook.f. & Thomson (●), I. tripetala Roxb. ex DC. (●) and I. trilobata Colebr. (●).

attenuate, margin crenate with small teeth to slightly serrate, papyraceous, adaxial pilose, abaxial glabrous, with 2–5 pairs of short hairs near lamina base and 2–many pairs of stipular glands at petiole base; lateral veins 8–12 pairs. Inflorescence axillary, erect, 2–10-flowered raceme. Peduncle 1–2(–11) mm long, c. 1 mm diam, glabrous. Rachis 1–10 mm long, c. 1 mm diam. Flowers 20–30 mm long, 20–30 mm deep, purple. Bracts 1–2 by <1 mm, lanceolate, apex acute, base cuneate, margin entire, glabrous, persistent. Pedicel 10–18 mm long, <1 mm diam, glabrous to remotely pilose. Lateral sepals 2, free, 2–3 by 1 mm, ovate to lanceolate, apex, base cuneate, green, glabrous to pilose. Lower sepal 14–18 mm long, 15–20 mm deep, saccate, apex acuminate, purple with yellow mark, glabrous to remotely pilose abaxially, distal part abruptly constricted into an incurved spur, 5–7 mm long, slightly bilobed. Dorsal petal 9–12 by 10–12 mm, broadly obovate to broadly elliptic, cucullate, apex emarginate, base round, purple, pilose, abaxial midvein with an obtuse crest or an acute appendage, 2–3 mm long. Lateral united petals 22–25 mm long, free: the upper petals 9–10 by 8–9 mm, broadly ovate to broadly obovate, apex round to truncate, base cuneate, purple; the lower petals 14–15 by 8–10 mm, free, ovate to elliptic, apex round and slightly obliquely emarginate, purple, glabrous, base with yellow auricle. Stamens: filaments 5–6 mm long. Ovary c. 5 mm long. Fruits 15–16 mm long, 2–3 mm diam, fusiform, glabrous. Seeds unknown.

Phenology — Flowering: July to October.

Distribution — Myanmar (Kachin State, Mandalay division, Shan State), India (Assam State), Bangladesh.

Ecology — Growing in organic matter on limestone in open areas, 1300–1600 m altitude.

Other collections examined. MYANMAR, Kachin State, Toppin 2680 (K H2015/00092 154, 155, 156), Sinlum, 1372–1524 m, 29 Sept. 1911; Toppin 2779 (K K000694906, K H2015/00092 157, 158, 159, 160), Sinlum, 24.284120, 97.382417,between Momauk and Balong Gatuang, N24°17'02.8" E97°22'56.7"; Murata , Kobayashi, Hayami & Takashima 040890 (MBK MBK0140389), 1–4 miles from Shinbweyan towards Pansaung. N 26°42'26" – 43'56" E 96°11'25" –12'33", alt. 190–270 m, forest margin, 6 Dec. 2005; Murata , Kobayashi, Hayami & Takashima 040884 (QBG QBG61256), ibid., 6 Dec. 2005; Mandalay Region, Ruchisansakun & Thet Yu Nwe 758 (L L2071186,MAND, RAF), N22°54.13' E96°22.62', alt. 1297 m, 22 Nov. 2015.

Notes — Impatiens tripetala is morphologically similar to I. trilobata but differs in having a short or inconspicuous peduncle <3 mm, while I. trilobata has a long peduncle exceeding 10 mm.

Impatiens tripetala is characterized by a large number of morphologically variable features. Leaves are mostly decussate, yet sometimes spirally arranged especially along the upper part of the stem. This variation can be found even at the population level, like in Toppin 2680.