Impatiens ecalcarata Collett & Hemsl.

Smets, E. F. & Janssens, S. B., 2018, Balsaminaceae of Myanmar, Blumea 63 (3), pp. 199-267 : 233-234

31. Impatiens ecalcarata Collett & Hemsl. — Fig. 15; Map 13; Plate 2f

Impatiens ecalcarata Collett & Hemsl. (1890) 30; (1891) 454; W.J. Kress et al. (2003) 169, non Impatiens ecalcarata Blank. (1905) 84, nom. illeg. = Impatiens ecornuta Moore ( Moore et al. 2012) 60. — Type: Collett & Hemsley s.n. (lecto, designated here illustration in Collett & Hemsley 1890 plate IV (Fig. 15)), Myanmar, Shan State, Shan Hills, alt. 4000 ft (1219 m).

Impatiens angustisepala Tardieu (1944) 180, syn. nov. — Type: Poilane 15637 (holo P P00780663), Laos, Pakson , Province de Bassac, alt. 1200 m, 19 Sept. 1919.

Terrestrial, annual herb, 25–40 cm tall. Stem erect, 2–3(–6) mm diam, cylindrical, unbranched to rarely branched, green to red, glabrous. Leaves decussate. Petiole sessile– 2 mm long, c. 1.5 mm diam, green to red. Lamina 45–60 by 4–9 mm, linear to narrowly oblong, apex acute, base truncate; lateral veins 4 or 5 pairs; margin shallowly serrate, adaxial green, abaxial pale green. Inflorescence axillary, erect, in 2-flowered fascicles. Flowers 9–10 by 9–10 mm, 7–8 mm deep, white to pale pink with purple reticulate lines at centre. Bracts c. 1 by <1 mm, linear, apex acute and mucronate, base cuneate, green to red. Pedicel 12–14 mm long, less 1 mm diam, reddish pink, abaxially pilose. Lateral sepals 2, 4–5 by 0.5–1 mm, free, linear, apex acute, base cuneate, pale pink with green tip, glabrous. Lower sepal 4.5–5 by c. 3.5 mm, c. 3 mm deep, navicular, apex acute and mucronate, white to pale pink with purple reticulate lines and yellow mark at centre, glabrous, spurless. Dorsal petal c. 4 by 5 mm, c. 1.5 mm deep, broadly ovate, cucullate, white with green tip, apex round and mucronate, base round, abaxial midvein with narrow crest terminating in a short acute point. Lateral united petals 9–10 mm long, free: the upper pair c. 3 by 1.5 mm, falcate to ovate, apex obtuse to acute, base cuneate, white; the lower petals 5–6 by 4–5 mm, free, orbicular, apex round, base obtuse, white with purple reticulate vein at the base. Stamens: filaments c. 2 mm long, white; anthers white to pale purple. Ovary c. 2 mm long, <1 mm diam, 5-carpellate, green, glabrous. Fruits 10–12 mm long, 3–4 mm diam, fusiform, 5-lobed, green, glabrous. Seeds c. 2 mm long, black and shiny.

Phenology — Flowering:April to November; fruiting:April to November.

Distribution — Myanmar (Shan State, Kayin State), Laos (Champasak Province).

Ecology — Growing in open areas, 500–1300 m altitude.

Other collections examined. LAOS, Poilane 15777 (para P P04542465), entre Pakson et Nong Bok Kao; Poilane 28442 (para P P04542464), ibid., 13 Nov. 1938 . – MYANMAR, Karen State, Ruchisansakun & Thet Yu New 747 (L L2071157, RAF, RANG), Hpa-An, Zwegabin mountain , N16°49'15.8" E97°40'19.5", alt. 481 m, 19 Oct. 2015 .

Notes — Impatiens ecalcarata is morphologically similar to other species with decussate leaves and flowers arranged in fascicles ( I. chinensis , I. helferi , I. masonii , I. oppositifolia ). However, it can be easily distinguished by its spurless lower sepal. The distribution of this taxon is unusual. It is known from southern and north-eastern Myanmar and Laos, but has not been found in Thailand so far.

Impatiens ecalcarata is identical to I. angustisepala , both in reproductive and vegetative parts. Hence, we decided to synonymize I. angustisepala under I. ecalcarata .

Collett & Hemsley (1890) mentioned that I. ecalcarata was collected in the Shan Hills at 4 000 ft. Since we could not find

Fig. 15 The lectotype Impatiens ecalcarata Collett & Hemsl. Illustration taken from Collett & Hemley (1860).

any specimens, but an illustration of this plant is present in the protologue (Collett & Hemsley plate IV), we select this as lectotype. Based on its small white flowers, we predicted that this species is an autogamous species, similar to I. muscicola ( Ruchisansakun et al. 2016) . Moreover, we found that the open stamens remain and touch the stigma.

Tardieu-Blot (1944) clearly designated Poilane 15637 as a type of I. angustisepala .