[Botany] Two new species of Impatiens L. (Balsaminaceae) from Arunachal Pradesh, Northeast India

Abstract. Two new species, i.e. Impatiens albopetala Gogoi & Borah and Impatiens dibangensis Gogoi & Borah, are described and illustrated here from Dibang Valley, Arunachal Pradesh, India.

Keywords: arunachal Pradesh; dibang Valley; Impatiens; new Species

Description Impatiens albopetala (Figure 1)

Perennial non succulent herbs up to 100 cm tall, stem branched, green with dark spots, glabrous, nodes swollen, rooting from the nodes. Leaves alternate, petiolate to subsessile, stipule papillate, with tip red, petiole 0.5–4.5 cm long, 1.5–3 mm in diameter, glabrous, slightly winged; blade simple, ovate to elliptic, 2.5–13.5 × 2–6.5 cm, margin serrulate, green, bristle between teeth, bristle reddish tipped; base obtuse, apex acuminate. Inflorescence axillary, racemose, equal to or longer than leaf, 7–14 cm long; peduncle green, ebracteate, with dark spots, glabrous, 3–7 cm long, 1–1.5 mm in diameter, 5- to 10-flowered. Flower yellow with white distal lobes in wings, bisexual, bracteate, bract 3–4 × 1 mm, triangular, green, apex acuminate, base truncate; pedicel green, 1.3–1.5 cm long, 1–1.5 mm in diameter. Lateral sepals four, in two pairs, bigger ones 3–4 × 1–1.5 mm, greenish, lanceolate, apex acuminate, small ones to 2 × 0.5–1 mm, tip black, linear lanceolate, green. Lower sepal tubular, 2.5–3 cm long, mouth 0.8–1 cm, oblique, beak down-curved, broad at the base, whitish, almost translucent, to 5 mm long, spur yellow with reddish spots, 1.8–2 cm long, tip yellow, erect, slightly up-curved. Dorsal petal yellow, obliquely oblong, deflexed, contorted along longer axis, 0.9–1 cm long, to 3 mm wide, mid-vein prominent, red spots in the abaxial surface, apex cuspidate. Lateral united petals (wings) yellow and white, 2.3–2.5 cm long (whole), bilobed, subequal, basal lobe yellow, curved, triangular, to 0.8 × 0.4 cm, apex acute, auricle inconspicuous, yellow, distal lobe white, 2 × 0.7 cm, upper portion semilunar and twisted along the longer axis, apex notched. Stamens five, encircling ovary, c. 3 mm long, capsule linear, slightly ribbed, green, 2–2.5 × 0.2 cm, seeds black when mature, surface rough, ovate, 1.5–2 × 1 mm.

Description Impatiens dibangensis (Figure 2)

Perennial non-succulent herbs, much branched, up to 80 cm tall, stem reddish, terete, ridged, nodes slightly swollen. Leaf confned to upper parts, alternate to spirally arranged, petiolate to subsessile, petiole 0.2–1.7 cm long, green, lamina elliptic, slightly coriaceous, dorsally light reddish, 3.7–13 × 2–4.7 cm, glabrous, base cuneate or slightly attenuate, apex acuminate, margin crenate, setose between teeth, stipule absent, veins 7–12 pairs, subopposite. Inflorescence axillary, longer than leaves, racemose, peduncle present, 4–10 cm long, up to 14 flowers. Flower yellow, pedicel 1.5–2.5 cm long, green, bract at the base, subulate, green, apex acute, to 1.5 × 0.5 mm. Lateral sepals two, subulate, green, 2 × 0.7 mm, apex acute, margin translucent, membranous. Lower sepal tubular, yellow, up to 2 cm deep, mouth without a beak or appendage inconspicuous, spur yellow, to 1.5 cm long, usually straight or slightly curved in apical portion, tip unifd; dorsal petal yellow, orbicular, dorsally greenish, noncucullate, to 8 × 9 mm, apex slightly emarginate, minutely beaked; lateral united petals yellow, bilobed, unequal, yellow, with red blotch, up to 2.4 cm long (whole), basal lobe obovate, up to 6 mm long, to 7 mm wide, apex acute, slightly clawed, distal lobe oblong-lorate, to 2 cm long, breadth up to 6 mm, apex obtuse, auricle minute. Stamens upright, 1.5 × 2.5 mm, anther lobes obtuse. Capsule linear, green, not ridged, up to 2.4 cm long, 1 mm width, seeds many, creamy. 

Reference: Rajib Gogoi & Souravjyoti Borah. 2016. Two new species of Impatiens L. (Balsaminaceae) from Arunachal Pradesh, Northeast India. Journal of Plant Taxonomy and Geography

http://dx.doi.org/10.1080/00837792.2016.1253913