Impatiens longipes Hook.f. & Thomson (1860: 151)

Gogoi, Rajib, Sherpa, Norbu & Borah, Souravjyoti, 2020, Taxonomic note on Impatiens longipes (Balsaminaceae) and description of the new species I. pseudolongipes, Phytotaxa 429 (3), pp. 217-224 : 218

Impatiens longipes Hook.f. & Thomson (1860: 151) ( Figure 1 & 2 ).

Lectotype (designated here):— Sikkim, Temperate region, 8000–10000 ft., Hooker , J.D. s.n., K000694799 ( K) image!; isolectotype P04543384 image!, P04543380 image!, P04543383 image!.

Annual, non succulent herbs, sparsely branched, up to 60 cm tall, stem terete, glabrous, slightly winged, nodes swollen at basal parts. Leaves confined to upper parts of stem, alternate, petiolate or sub-sessile, petiole 1.2–2 cm long, green with pink blotch sometimes, stipular gland triangular; blade elliptic to elliptic–lanceolate, 3–11 × 1–2.5 cm, ventrally deep green, dorsally pale green, glabrous; base obtuse, cuneate to slightly attenuate, apex acuminate, margin crenate, setose at tip of the teeth; lateral veins 4–5 pairs, subopposite. Inflorescence axillary, arched-spreading, long pedunculate, 5.5–7.5 cm long, 2–7 flowered, bud greenish-yellow. Flower yellow, asymmetrical, pedicellate, pedicel ca. 1–1.2 cm long. Bract at the base, lanceolate, 4–5 mm long, apex aristate, green, glabrous, caducous, mid vein prominent. Lateral sepals usually 2, rarely 4 (inner pair minute, lanceolate and hyaline), outer pair ovate, ca. 4 × ca. 2 mm, apex acute, margins transparent, yellowish green, glabrous. Lower sepal navicular, 1–1.4 cm deep, mouth minutely beaked, yellow, glabrous, spurred; spur 0.5–0.9 cm long, inflexed curved or hooked curved, yellow, tip unifid. Dorsal petal yellow, cucullate, sub-orbicular ca. 0.8 × ca. 0.9 cm, apex rounded, without beak, dorsal ridge prominent only in buds, ridge greenish. Lateral united petals yellow without any blotch, bilobed, unequal, 2.2–2.8 cm long (whole); basal lobe ca. 0.8 × ca. 1.0 cm, obovate, apex acute, not clawed; distal lobe long lorate, 1.2–2 × ca. 0.2 cm, twisted, gradually narrowing towards apex, apex acute, auricle minute, orange. Stamen 5, united, encircling the ovary. Capsule linear, 2–3 cm long, smooth, to 1.5 mm in width; seed 1–1.5 mm, pyriform, surface papillate.

Phenology —May–October.

Habitat and ecology —Margins of moist shady mountain slopes of upper subtropical or lower temperate mixed forest of Yushania maling ( Gamble 1912: 139) R.B.Majumdar & Karthik. (1989: 283) along with Impatiens stenantha Hook.f. (1875: 478) and Pilea scripta (Buch.-Ham. ex D. Don 1825: 59) Wedd. (1854: 187)

Distribution: Sikkim (North Sikkim), West Bengal: Darjeeling, Sinchel, Tiger Hills; BHUTAN: Tongsa district; CHINA: Tibet, Yadong (Yatung).

Lectotypification. Impatiens longipes was described by J. D. Hooker and T. Thomson on the basis of J. D. Hooker’s own collection from the then Sikkim Himalaya. In the protologue, he also mentioned a collection made by Strachey and Winterbottom from Kumaon, Western Himalaya. In the present study Strachey and Winterbottom’s collections could not be located for study either at K, P or CAL but all the collections from J. D Hooker are extant at K and P. The syntype J.D. Hooker s.n. (K000694799) is with annotations by J. D. Hooker himself and clearly matched with the descriptions given in the protologue, hence it is designated as lectotype as per Art. 9.3 of Shenzhen Code ( Turland et al. 2018). The isolectotypes (P04543384, P04543380, P04543383) are at P. W. Griffith collected three specimens of Impatiens from Eastern Himalaya which are also extant at P (P04543379, P04543381 & P04543382) and they were also studied by J. D. Hooker and determined as I. longipes . The identity of these three specimens are, however, still doubtful because they do not agree with the characters with I. longipes as the flowers in the specimens are lacking the inflexedly curved or hookedly curved spur as well as the twisted lorate distal lobe of lateral united petals.

Figures

FIGURE 2. Lectotype of Impatiens longipes Hook.f. & Thomson Hooker, J.D. s.n., K000694799 © The Board of Trustees of the Royal Botanic Gardens, Kew, reproduced with the permission of the Royal Botanic Gardens, Kew.

FIGURE.1. Impatiens longipes Hook.f. & Thomson: a. habit of the plant, b. dorsolateral view of flower, c. inflorescence, d. lateral view of flower bud, e. bract, f. lateral sepals, g. lateral view of lower sepal and spur, h1. ventral view of lateral united petals, h2. dorsal view of lateral united petals, i1. dorsal view of dorsal petal, i2. ventral view of dorsal petal, j. capsule. (photos by R. Gogoi)