Impatiens kerriae Craib

Smets, E. F. & Janssens, S. B., 2018, Balsaminaceae of Myanmar, Blumea 63 (3), pp. 199-267 : 214

4. Impatiens kerriae Craib — Fig. 9; Map 4; Plate 1c

Impatiens kerriae Craib (1926a) 161; (1926b) 210; T. Shimizu (1970) 189. — Type: Kerr 6544 (lecto, designated here ABD*; isolecto BK BK257749 , BM BM000797447,K K000675564), Thailand, Chiang Mai,Doi Chiengdao, alt. 1800 m, 3 Nov. 1922.

Lithophytic, perennial, glabrous herb, 1.5–3 m tall. Stem erect, cylindrical, the main stem part c. 80 mm diam, moderately to richly branched, the branches c. 10 mm diam green to grey to brown, marked with old leaf scars. Leaves spirally arranged. Petiole 30–90 mm long, 2–4 mm diam, pale green. Lamina 160–260 by 70–95 mm, ovate to elliptic, apex acuminate, base attenuate to cuneate, margin serrate, sometimes unequal, coriaceous; lateral veins (6–)15–17 pairs, with a red globose gland on each side of the upper margin at the base, adaxial green, abaxial pale green. Inflorescence axillary, pendulous, 2-flowered fascicle. Peduncle very short, <1 mm long, c. 2.5 mm diam, green. Flowers 30–37 by 25–33 mm, 28–30 mm deep, slightly asymmetric, white to pale pink, yellow lip with red lines. Bracts 2–3 by 2 mm, triangular, apex acute, base cuneate, margin entire, pinkish green, persistent. Pedicel 40–80(–120) mm long, 1.5–2 mm diam, cylindrical, pale green. Lateral sepals 2, 17–20 by 12–16 mm, free, elliptic to ovate, cucullate, apex acute to acuminate and mucronate, base obtuse, pale pink with some large red spots and green tip. Lower sepal 20–22 by 15–19 mm, 11–13 mm deep, navicular, apex obtuse and mucronate, base obtuse, white to pale pink, sometimes with dark pink tinge at the distal part, distal part abruptly constricted into a short incurved and deeply bilobed spur, 8–10 mm long, green. Dorsal petal 15–17 by 12–13 mm, elliptic, cucullate, apex round to slightly emarginate and mucronate, base obtuse, white to pale green, abaxial midvein simple or with a narrow crest terminating in a short acute point. Lateral united petals 32–35 mm long, connate: the upper petals 10–16 by 10–13 mm, orbicular to obovate, apex truncate, base cuneate, white with yellow base and red lines; the lower petals 25–28 by 6–8 mm, connate, oblong to narrowly ovate, apex obtuse, yellow with red lines. Stamens: filaments c. 5–6 mm long, pale green; anthers pale yellow. Ovary 5–6 mm long, 4-carpellate, green. Fruits 30 mm long, 7 mm diam, clavate, 4-lobed, green. Seeds 16–30, brick shaped, c. 2.5 mm long, brown, pilose.

Phenology — Flowering: November to December; fruiting: November to January.

Distribution — Myanmar (Shan State), northern Thailand. Ecology — Growing on limestone in shady or open areas in mixed deciduous forest, 1200–2200 m altitude.

Other collections examined. MYANMAR, Shan State, Makino BG exped. 3274 (L, MBK, RAF), Taunggyi District; Ruchisansakun & Makino BG 737 (L, MAND, RAF), Taunggyi District, Nagali village , N21°07'32.67" E96°23'47.82", alt. 1257 m, 29 Sept. 2015 .

Notes — Impatiens kerriae is a new record for Myanmar, previously only found in Thailand. It is very similar to I. parishii but differs in having a longer pedicel than petiole, 2 lateral petals, and wavy red streaks on the lower lateral united petals, while I. parishii always has a yellow mark at the base of the lower lateral united petals.

The population in Taunggyi differs from the population in Chiang Mai in having longer petioles (65–90 mm vs <10 mm), much larger laminas (16–26 by 7–95 mm vs 110 by 60 mm), and in the number of lateral veins (14–16 vs 6–12). These differences may be explained by the higher altitude of the Chiang Mai site, where a windy and nutrient-poor environment may lead to reduced growth. Hooker annotated the specimens Khalil s.n. (K K000694776) and Lace 4154 (K H2015/00092 27) as I. platysepala , non Impatiens platysepala Y.L. Chen (1988) 6, but this was never officially published. We found no differences between those specimens and I. kerriae .

This species is pollinated by bumblebees ( Ruchisansakun et al. 2016). Due to the asymmetric lower lateral sepals, the body of the bumblebee tilts over to the right-hand side when it enters the flower resulting in the deposition of the pollen on the left side of the upper thorax.