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| Impatiens cirrosa Nob.Tanaka & T.Sugaw., in Tanaka, Aung et Sugawara, 2026. Photographed by T.Sugawara. |
Abstract
Two new species, Impatiens arakanensis Nob.Tanaka & T.Sugaw. (Balsaminaceae) and I. cirrosa Nob.Tanaka & T.Sugaw., from the Arakan Mountain Range, Magway Region, southwestern Myanmar, are described here. Impatiens arakanensis is similar to I. decipiens Hook.f. in floral morphology and coloration, but differs in having axillary inflorescence (vs. terminal), smooth dorsal petals (vs. with horn-like appendage), and pubescent lower sepal (vs. glabrous). Impatiens cirrosa is similar to I. tripetala Roxb. in floral morphology, but differs in having purple lower sepals (vs. orange to pale orange) with filamentous cirrus at apex, connate lateral united petals (vs. free) and white ovary with red spots (vs. green). Both of the two new species likely belong to Impatiens subgenus Impatiens sect. Uniflorae.
Keywords: Arakan, balsam, Burma, new taxon, sect. Uniflorae, taxonomy
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| Impatiens arakanensis. A. Habit. B. A diagonal front view of flower. C. A front view of flower. D. A side view of flower. E. Dissected flower, showing lower sepal, dorsal petal, and lateral united petals. Scale bars: 10 mm. Photographed by T.Sugawara. |
Impatiens arakanensis Nob.Tanaka & T.Sugaw., sp. nov.
Impatiens arakanensis is similar to I. decipiens in floral morphology and purplish coloration, but distinguished from it by having an axillary inflorescence (vs. terminal inflorescence), smooth dorsal petals (vs. with horn-like appendage), and pubescent lower sepal (vs. glabrous).
Etymology: The specific epithet “arakanensis” refers to the name of the Arakan Mountain Range in which its type locality is located.
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| Impatiens cirrosa. A. Habit. Arrows showing a filamentous cirrus. B, C. A diagonal front view of flower, showing a filamentous cirrus. D. A front view of flower. E. Dissected flower: a. Lower sepal. b. A young fruit with pedicel. c, d. Lateral united petals. e. Dorsal petal. Scale bars: 10 mm. Photographed by T.Sugawara. |
Impatiens cirrosa Nob.Tanaka & T.Sugaw., sp. nov.
Impatiens cirrosa is similar to I. tripetala in floral morphology, but distinguished from it by having purple lower sepals (vs. orange to pale orange) with filamentous cirrus at apex, connate lateral united petals (vs. free) and white ovary with red spots (vs. green).
Etymology: The specific epithet “cirrosa” refers to the most distinctive character of Impatiens cirrosa, which is a very distinct species with long filamentous cirrus at the apex of the lower sepal and lower margin of lamina (Figs. 3B, E, 5).
Nobuyuki Tanaka, Mu Mu Aung and Takashi Sugawara. 2026. Contributions to the Flora of Myanmar X: Two New Species of Impatiens (Balsaminaceae) from the Arakan Mountain Range of Myanmar. J. Jap. Bot. 101(2); 88-96. DOI: doi.org/10.51033/jjapbot.ID0361 [April 20, 2026]
