Impatiens oblongata Ruchis. & Niet

Smets, E. F. & Janssens, S. B., 2018, Balsaminaceae of Myanmar, Blumea 63 (3), pp. 199-267 : 240

40. Impatiens oblongata Ruchis. & Niet — Map 15; Plate 3f

Impatiens oblongata Ruchis. & Niet (in Ruchisansakun et al. 2018) 70. — Type: Ruchisansakun & Makino BG Exped. 735 (holo L L2071128; iso L L2071129,L L2071130,L L2071131,RAF,RANG), Myanmar, Shan State, Kalaw , N20°39'24" E96°34'96", alt. 1569 m, 27 Sept. 2015.

Terrestrial, annual herb, 30–50 cm tall. Stem erect, 1–4 mm diam, angular, simple, or moderately to richly branched, red, glabrous, only remotely pilose towards apex. Leaves spirally arranged. Petiole 3–10 mm long, c. 1 mm diam, pale green to pink, pilose. Lamina 50–75 by 10–20 mm, lanceolate to narrowly ovate, apex acute, base cuneate to attenuate, margin serrate, adaxial green, abaxial pale green, pilose on both sides, with 3–5 long red hairs along the margin near the base; lateral veins 6 or 7 pairs. Inflorescence axillary, erect, solitary. Flowers 19–20 by 16–18 mm, 14–17 mm deep, pink, with small dark pink dots and small yellow dots at the centre. Bracts c. 2 mm by <1 mm, linear, apex acute, base cuneate, green with red apex, pilose, persistent. Pedicel 18–20 mm long, <1 mm diam, pink, pilose. Lateral sepals 4, sometimes the upper pair reduced: the upper pair c. 2 by <1 mm, sometimes absent, linear to oblong, apex acute, base cuneate, pale green with red tip, pilose; the lower pair 1.5–2 by 1.5–2 mm, ovate, apex acuminate, base obtuse, pink, glabrous. Lower sepal 5–6 by 3–4 mm, 3–4 mm deep, navicular, apex acuminate and mucronate, pale pink with dark pink mark near the base, pilose outside, distal part abruptly constricted into a straight or curved spur, 8–12 mm long, pink with dark pink tip. Dorsal petal 5–6 by 6–9 mm, broadly obovate, flat, apex truncate and stipitate, up to 2 mm long, base truncate, pink with green stipitate tip, glabrous with pilose midrib and tip, abaxial midvein with an acute appendage, <1 mm tall, pink or green. Lateral united petals 12–14 mm long, free: the upper petals 7–8 by 4–5 mm, broadly oblong, apex truncate to slightly emarginate, base cuneate, pink; the lower petals 10–11 by 4–5 mm, free, elliptic to obovate, apex truncate to slightly bilobed, pink with yellow dot and dark pink dot at the base. Stamens: filaments c. 2.5 mm long, pale pink; anthers pale pink. Ovary c. 2 mm long, c. 1 mm diam, 5-carpellate, green, pilose with short hairs. Fruits 15–20 mm long, 4–5 mm diam, fusiform, 5-lobed, green, pilose with short hairs. Seeds 6 or 7, c. 3 mm long, ovoid, brown.

Phenology — Flowering: September to October; fruiting: September to October.

Distribution — Endemic to north-eastern Myanmar (Shan State), only known from the type locality.

Ecology — Growing in shady areas at the top of the mountain in open fragmented evergreen forest, 1500–1600 m altitude.

Note — Impatiens oblongata usually has four lateral sepals, rarely two, in contrast to similar species, such as I. patula , I. violiflora , I. curvipes and I. florulenta .