Impatiens masonii Hook.f.

Smets, E. F. & Janssens, S. B., 2018, Balsaminaceae of Myanmar, Blumea 63 (3), pp. 199-267 : 234-235

32. Impatiens masonii Hook.f. — Map 13; Plate 2g

Impatiens masonii Hook.f.(1905) 29,34; W.J. Kress et al. (2003) 170. — Type: Badalkhan 119 (lecto, designated here K K000694709), Myanmar, upper Burma, Mandalay district, 40 miles from Mandalay, July 1888.

Impatiens craddockii Hook.f.(1905) 29, 34; Craib (1926b) 210;Tardieu (1945) 562; W.J. Kress et al. (2003) 169, syn. nov. — Type: Craddock 58 (lecto, designated here K K000694704;isolecto K K000694703), Myanmar,upper Burma, Nahi, alt. 3800 ft (1158 m), July 1901.

Impatiens pseudochinensis T. Shimizu (1969) 37, syn. nov. — Type: Shimizu, Hutoh, Chaiglom T­8932 (holo KYO not seen; iso BKF006048, E E00313656), Thailand, Loei, Phu Kradueng , Phu Kradueng National Park , on the plain at its summit, alt. 1200 m.

Terrestrial, annual, glabrous herb, 50–100 cm tall. Stem erect, 3–3.5 mm diam, unbranched, green to reddish green to red, glabrous. Leaves decussate. Petiole sessile– 2 mm long, up to 1 mm diam, green, glabrous. Lamina 60–90 by 10–15 mm, narrowly elliptic, apex acute, base cuneate, margin serrate, adaxial green and scabrous, abaxial greyish green and glabrous, with one pair of globose stipular glands at petiole base; lateral veins 4 or 5 pairs. Inflorescence axillary, 1- or 2-flowered fascicles. Peduncle c. 1.5 mm long, c. 1.5 mm diam, green to red, glabrous. Flowers c. 35 by 30 mm, c. 40 mm deep, pink. Pedicel 40–45 mm long, c. 1 mm diam, green to red, glabrous. Bracts c. 3 by 1 mm, triangular, apex acute, base cuneate, margin entire, green, glabrous, persistent. Lateral sepals 2, 10–11 by c. 6 mm, free, ovate to lanceolate, apex mucronate, base obtuse, red with green apex, glabrous. Lower sepal c. 15 by 5 mm, c. 12 mm deep, navicular, apex acute and mucronate, base obtuse, deep pink, distal part gradually constricted into a straight or incurved spur, 23–27 mm long, red with green tip. Dorsal petal c. 19 by 26 mm, broadly elliptic, flat, recurved backward at the middle, apex obcordate, base round, abaxial midvein with narrow crest, pink with darker pink on crest, glabrous. Lateral united petals c. 30 mm long, free: the upper petals 15 by 9 mm, falcate, apex round, base cuneate, pink; the lower petals c. 23 by 17 mm, free, ovate to elliptic, apex round, pink, glabrous. Stamens: filaments c. 4 mm long, pink; anthers yellow. Ovary c. 3.5 mm long, c. 1 mm diam, 5-carpellate, green, glabrous. Fruits c. 16 mm long, c. 5 mm diam, fusiform, 5-lobed, green, glabrous. Seeds 7–12, ellipsoid, c. 2 mm long, brown.

Phenology — Flowering: July to September; fruiting: September to November.

Distribution — Myanmar (Mandalay, Shan State), Thailand (Chaiyaphum, Chiang Mai, Lamphun, Loei, Phetchabun).

Ecology — Growing among grasses in open grassland or mixed montane forest, 1200–1600 m altitude.

Other collections examined. MYANMAR, Mandalay Region, Lace 3269 (E E00753105, E E00753106), Maymyo, alt. 3500 ft, 7 July 1908 ; Lace 1016 (K), ibid., Shan State; Ruchisansakun et al. 720 (L L2071093, MAND, RAF), Taunggyi district, on the way to Shwephonpwiat , N20°46'00.79" E97°03'36.03", alt. 1578 m, 19 Sept. 2015 ; Ruchisansakun et al. 724 (L L2071102, MAND, RAF), N20°50'51.62" E97°14'14.34", alt. 1196 m, 20 Sept. 2015 ; Ruchisansakun et al. 728 (L L2071113, MAND, RAF), Sangaw village , N20°45'49.78" E97°18'20.73",alt. 1501 m, 23 Sept.2015 .– THAILAND, Bunpheng 571 (para BKF), Loei, Phu Kradueng, Phu Kradueng National Park , on the plain at its summit, alt. 1200 m .

Notes — Impatiens craddockii and I. pseudochinensis were published as distinct species because they seemingly differed in the shape of their lateral sepals, leaves, and in floral size.

Map 13 Distribution of Impatiens ecalcarata Collett & Hemsl. (●), I. masonii Hook.f. (●), I. chinensis L. (●) and I. oppositifolia L. (●).

However, since these characters vary continuously, both names are synonymized under I. masonii . The names I. masonii and I. craddockii were published in the same publication ( Hooker 1905). However, the description of I. masonii comes before that of I. cradockii , so I. masonii is regarded as the accepted name and I. craddockii as a synonym.

Impatiens masonii is most similar to I. chinensis but differs in having large upper lateral petals and ovate to lanceolate lateral sepals as opposed to I. chinensis . Moreover, I. masonii is always associated with non-swampy grasslands whereas I. chinensis always grows in swampy areas.

Hooker (1905) did not designate types for I. masonii and I. craddockii . We select Badalkhan 119 (K000694709) as lectotype of I. masonii because it is the only specimen with illustrations by Hooker. For I. craddockii , we found two specimens and select Craddock 58 (K000694704) because it provides more details.