Impatiens forrestii Hook.f. ex W.W.Sm.

Smets, E. F. & Janssens, S. B., 2018, Balsaminaceae of Myanmar, Blumea 63 (3), pp. 199-267 : 219-220

10. Impatiens forrestii Hook.f. ex W.W.Sm. — Map 6

Impatiens forrestii Hook.f. ex W.W.Sm. in Smith & Forrest (1915) 339; Grey-Wilson (2008) 139. — Type: Forrest 4275 (lecto, designated by Grey-Wilson (2008) E E00313622; isolecto K000694041), China, West Yunnan, inside valleys on the eastern flank of the Tali Range, lat. N25°40', alt. 9000–10000 ft, July 1906.

Perennial herb, 30–90 cm tall, swollen and semi-woody at the very base, with fascicled roots. Stem erect, slender, unbranched to sparsely branched, green to purple, glabrous to papillate at the upper nodes. Leaves spirally arranged. Petiole 2–26 mm long, slender, glabrous. Lamina 70–150 by 30–54 mm, elliptic to ovate to lanceolate, apex acute to acuminate, base cuneate to attenuate, margin serrate, membranous, adaxial deep green and pilose, abaxial pale green and remotely pilose; lateral veins 5–6(–9) pairs. Inflorescence axillary, erect when young but pendulous in mature stage, (1- or) 2- (or 3-)flowered raceme. Peduncle 30–70 mm long, slender, green to purple, pilose to glabrous, with two glands on each side of peduncle base. Rachis 3–12.5 mm long. Flowers 26–38 mm long, 30–37 mm deep, purple to red, with dark red lines on the lower sepal and the lateral united petals. Bracts 2.5–5 by 1–4 mm, lanceolate to elliptic, apex mucronulate, base obtuse, margin entire, without gland, abaxially pilose, persistent. Pedicel 7–20 mm long, slender, glabrous. Lateral sepals 2, 7–9 by 5–7 mm, free, ovate to obliquely ovate, apex mucronulate, base obtuse to truncate, abaxial glabrous to pilose. Lower sepal 15–25 mm long, 14–18 mm deep, deeply bucciniform with an oblique mouth, apex acuminate and mucronate, glabrous to slightly pilose, abruptly constricted into an incurved and spiral spur, 10–19 mm long, slightly bilobed at the tip of the spur. Dorsal petal 12–20 by 18– 27 mm, broadly ovate to broadly elliptic, flat, apex emarginate, base truncate, pink, slightly pilose near the midrib, abaxial midvein with a keel-shaped crest and long acute appendage, 5–6 mm long. Lateral united petals 25–35 mm long, free: the upper petals 10–13.5 by 7.5–8 mm, obovate to orbicular, apex obtuse, base cuneate, pink; the lower petals 28–30 by 12–15 mm,

Map 6 Distribution of Impatiens forrestii Hook.f. ex W.W.Sm.

free, obovate, apex slightly obliquely emarginate, base auricled, glabrous. Stamens: filaments 5–5.5 mm long; anthers acute. Ovary up to 5 mm long, c. 1.5 mm diam, glabrous. Fruits 22–30 mm long, linear, green, glabrous.

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

Distribution — Northern Myanmar (Kachin State), southwestern China (Yunnan, Sichuan).

Ecology — Growing in shady and moist areas in evergreen forest, 2500–3000 m altitude.

Other collections examined. MYANMAR, upper Burma , Forrest 1002 (para K H2015/60092 18), on the Irrawadi-Ming-Kwang divide,also in the Irrawadi basin, lat. N25°50', alt. 8000–10000 ft, Oct. 1905 .

Note — This species is slightly similar to I. arguta but differs in having a keel-shaped crest and a long acute appendage on the abaxial midvein of dorsal petal instead of crescent-shaped to obtuse crest without appendage ( Fig. 3).

Section Racemosae Hook.f. & Thomson (1860) 113