Impatiens rangoonensis Hook.f.

Smets, E. F. & Janssens, S. B., 2018, Balsaminaceae of Myanmar, Blumea 63 (3), pp. 199-267 : 244-246

48. Impatiens rangoonensis Hook.f. — Map 17; Plate 4b

Impatiens rangoonensis Hook.f.(1905) 29,34; Fedde (1905) 433; W.J. Kress et al. (2003) 170. — Type: King 4772B (lecto, designated here K K000694745), Myanmar, Rangoon, 14 Aug. 1879.

Terrestrial, annual, glabrous herb, 27–40 cm tall. Stem erect, cylindrical, 2–4 mm diam, sparsely branched, green. Leaves spirally arranged. Petiole 5–35 mm long, c. 1 mm diam, red. Lamina 45–85 by 30–42 mm, ovate to elliptic, apex acute, base obtuse to attenuate; lateral veins 4–6 pairs; margin shallowly crenate with many long hairs near the base, adaxial green, abaxial pale green. Inflorescence axillary, erect, in 9–16-flowered racemes. Peduncle 45–90 mm long, c. 1 mm diam, cylindrical, red, glabrous. Rachis 10–40 mm long, <1 mm diam. Flowers 11–12 by 12–13 mm, 10–11 mm deep, pale pink. Bracts 2.5–3 by 1.5–2 mm, ovate, apex acute and mucronate, base cuneate to obtuse, green with red dots, bright green tip. Pedicel 5–8 mm long, <1 mm diam, green, glabrous, persistent. Lateral sepals 2, 2.5–3 by 1.5–2 mm, free, elliptic, apex acute, base obtuse, green, glabrous. Lower sepal 5–6 by 3.5 mm, c. 3 mm deep, navicular, apex acuminate and mucronate, recurved, pale green, distal part rapidly constricted into a long spur, 18–21 mm long, pink with white tip, blunt. Dorsal petal

Plate 4 a. Impatiens circaeoides Wall. ex Hook.f. & Thomson ; b. Impatiens rangoonensis Hook.f. ; c. Impatiens tripetala Roxb. ex DC. ; d. Impatiens porrecta Wall. ex Hook.f. & Thomson ; e. Impatiens andersonii Hook.f. ; f. Impatiens gongshanensis Y.L.Chen ; g, h. Impatiens pulchra var. pulchra Hook.f. — Photos by: a–e, g, h. Saroj Ruchisansakun; f. Saw-Lwin.

c. 4 by 3 mm, ovate, cucullate, pale green, apex acute and mucronate, base cordate, abaxial midvein simple or with a narrowly crescent-shaped crest. Lateral united petals 11–14 mm long, free: the upper petals c. 1 by 1 mm, orbicular, apex obtuse, base cuneate, white to pale green; the lower petals 8–12 by 5–7 mm, free, ovate, apex acute, base cuneate, pale pink with dark pink mark at the base. Stamens: filaments c. 2 mm long, white; anthers white. Ovary 2 mm long, <1 mm diam, 5-carpellate, green, glabrous. Fruits 8–9 mm long, 2.5–3 mm diam, fusiform, 5-lobed, green, glabrous. Seeds 10–13, c. 2 mm long, brown.

Phenology — Flowering: July to August; fruiting: July to August.

Distribution — Endemic to Myanmar (Rakhine State, Yangon Region).

Ecology — Growing in shady areas near water canals along the roadside, 0–10 m altitude.

Other collections examined. MYANMAR, Rakhine State, Ruchisansakun & Salwin 702 (L L2071059, RAF, RANG), Thandwe district , N18°29'39.8" E94°22'23.6",alt.c. 13 m, 30 July 2015 ; Yangon Region, Parkinson 14634 (K H2015/00092),(Rangoon), Inyalake ( Victoria Lake ), 15 July 1932; M’Clelland s.n. (E E00753093) , Rangoon.

Notes — The vegetative parts of I. rangoonensis are very similar to I. circaeoides but the flowers are distinctly different by virtue of its ovate sepals and long spur.

Hooker (1905) did not designate a type. We found only one specimen, King 4772B (K000694745), with the name I. rangoonensis on the sheet. It matches the protologue, so we selected it as lectotype.

Fig. 18 Impatiens tavoyana Benth.ex Hook.f. & view of flowers;c. fruit;d. lower lateral sepals;e. petals. — Drawn by Saroj Ruchisansakun.