Impatiens hartnolliae Hook.f. ex Ruchis. & Suksathan

Smets, E. F. & Janssens, S. B., 2018, Balsaminaceae of Myanmar, Blumea 63 (3), pp. 199-267 : 242

44. Impatiens hartnolliae Hook.f. ex Ruchis. & Suksathan — Map 16

Impatiens hartnolliae Hook.f. ex Ruchis. & Suksathan in Ruchisansakun et al.(2018). — Type: Hartnoll s.n. (holo K K000694663), Myanmar (Burma), Rakhine State (Arakan), Akyab, Urittaung pagoda, 5 Sept. 1907 .

Terrestrial, annual herb, up to 36 cm tall. Stem erect, c. 12 mm diam, richly branched, glabrous. Leaves spirally arranged. Petiole 6–12 mm long, c. 1 mm diam, glabrous. Lamina 110–120 by 45–50 mm, ovate to elliptic, apex acute to acuminate, base round to obtuse to cuneate, margin crenate to serrate, adaxial glabrous to remotely pilose, abaxial glabrous, with 2 or 3 pairs of long hairs along the margin near lamina base; lateral veins

Map 16 Distribution of Impatiens hartnolliae Hook.f.ex Ruchis.& Suksathan (●), I. parkinsonii C.E.C.Fisch. (●), I. peguana Hook.f. (●) and I. circaeoides Wall. ex Hook.f. & Thomson (●).

8 or 9 pairs. Inflorescence subterminal, erect, 6- or 7-flowered racemes. Peduncle 10–15 mm long, c. 1 mm diam, glabrous. Rachis 7–14 mm long, c. 1 mm diam. Flowers c. 18 mm long, c. 15 mm wide, c. 23 mm deep. Pedicel 9–10 mm long, c. 1 mm diam, glabrous. Bracts 2.5–3.5 by 1.5–2 mm, ovate, apex acute to mucronate, base round, margin entire, glabrous, persistent. Lateral sepals 2, 6.2–6.6 by 7.5–8 mm, free, orbicular to broadly elliptic, apex round to mucronate, base round, glabrous. Lower sepal c. 10 mm long, c. 8 mm deep, navicular, apex acuminate to mucronate, glabrous, distal part gradually tapering into a straight or curved spur, 15–17 mm long. Dorsal petal c. 6.5 by 8 mm, broadly obovate, apex emarginate, base obtuse, truncate, glabrous, abaxial midvein simple or with a narrow crest. Lateral united petals c. 15.5 mm long, free: the upper petals 9–10 by 5–5.5 mm, obliquely broadly oblong, apex truncate and slightly emarginate, base cuneate; the lower petals 8.5–9 by 3.5–4 mm, free, oblong, apex truncate, base without auricle. Stamens: filaments 4–5 mm long; anthers obtuse. Ovary c. 3.5 mm long, c. 1 mm diam, glabrous. Fruits fusiform, glabrous. Seeds ellipsoid, c. 1.6–2 mm long, pilose.

Phenology — Flowering: September; fruiting: September.

Distribution — Endemic to Myanmar (Rakhine State).

Ecology — Growing in limestone soils.

Note — Impatiens hartnolliae can easily be distinguished from other Myanmar species by racemose inflorescence, truncate lateral united petals, an emarginate dorsal petal and a fusiform fruit.