Impatiens violoides Edgew. ex Hook. f.

Sharma, Ashutosh, Adamowski, Wojciech, Naithani, Harsh Bardhan & Begum, S. Noorunnisa, 2024, Rediscovery of rare steno-endemic Impatiens violoides Edgew. ex Hook. f. (Balsaminaceae) from Western Himalaya, after 179 years of type collection, Phytotaxa 644 (1), pp. 42-48 : 43-46

Impatiens violoides Edgew. ex Hook. f. in Rec. Bot. Surv. India 4: 5. 1904; Fig. 1 , 2 .

Type:— INDIA. near Junglung , 7000–8000 feet, October 1844, M.P. Edgeworth 342 ( K000694928 !)

Annual herbs; stems erect 25–150 cm tall, succulent, dark violet to green, swollen at lower nodes. Leaves alternate, aggregated at the branches apex, petiole 15–60 mm long; lamina broadly lanceolate to oblong-ovate, 7–12 cm × 3.5–9 cm, green, glabrous with crenate margins, base cuneate, apex acuminate; veins 6–9; two glands at the base of petiole 1–2 mm long. Inflorescence variable, interrupted long raceme or subumbellate, 6–14 cm long, axillary, few (3) to many (20) flowered. Flowers bisexual, zygomorphic, often congested on top of peduncle. Pedicel 1–2 cm long, slender, rusty brown, glabrous, with a persistent bract at base. Bracts 3–3.5 mm long, narrowly ovate, acute at apex. Flowers white, 2.6–3.2 cm × 1.2–2.5 cm. Lateral sepals two, purplish, ovate, 3 mm long; lower sepal navicular, 12–15 mm long, 5–6 mm wide, 3–4 mm deep, white with rusty orange base and acute tip; spur absent. Dorsal petal white, 7–10 mm × 14–15 mm, cucullate, with thickened purplish midrib, ending in a short horn or appendage, 1–2 mm long; lateral united petals 22–25 mm long, white, orange-yellowish at the base of the lower lobe with dark purplish rusty streak markings, lower lobe broadly dolabriform, 8–10 mm wide, 15–18 mm long; upper lobe 7–8 mm long, 8–9 mm wide. Stamens five; anthers with appendage. Capsules unevenly linear, sometimes deflexed upward at maturity, 2.3–3 cm long, glabrous, green to partially reddish with pale yellowish stripes, enclosing 2–5 seeds. Seeds ca. 3.5 mm long.

Phenology:—Flowering from early July, commencing along with fruiting until September end. Seeds ripen and dehisce in September–October.

Species etymology:—Specific epithet ‘violoides’ refers to Viola like flower of this species as its navicular shaped lower sepal resembles spur of Viola flower.

Distribution:— India, Himachal Pradesh (Rohru sub-division, Shimla District).

Habitat and Distribution:— Impatiens violoides is a terrestrial species growing under dense moist coniferous forest of Abies pindrow (Royle ex D.Don) Royle (1836:86) and Cedrus deodara (Roxb. ex D.Don) G. Don (1830:388) in small colonies and in association with Fragaria nubicola (Lindl. ex Hook.f.) Lacaita (1916:467) , Halenia elliptica D. Don (1837:529) , Impatiens brachycentra Kar. & Kir. (1842:179) , Impatiens laxiflora Edgew. (1846:40) , Impatiens sulcata Wall. (1824:458) , Parthenocissus semicordata (Wall.) Planch. (1887:451) , Persicaria nepalensis (Meisn.) H. Gross (1913:277) and Viburnum grandiflorum Wall. ex DC. (1830:329) etc. Three images of this species from below Chanshal Pass area can be seen on eFloraofIndia portal, tentatively identified by second author (WA) in 2017 (eFloraofIndia). Impatiens violoides is distributed between 2,500 –3,400 m elevation in dense temperate conifer forests in Rohru valley, Shimla district of Himachal Pradesh.

IUCN Red List assessment:— Impatiens violoides was originally described based on a single collection of M.P. Edgeworth in 1844 from Janglig/Junglung, below Chanshal Pass, Shimla, Himachal Pradesh. It remained as a little known species for almost 18 decades with no re-collections done. Based on our field surveys from 2018–2023 and literature surveys, 3 subpopulations are known to exist in the distribution range with each estimated to contain an average of less than 500 mature individuals comprising an overall population size of less than 1500 mature individuals. Many individuals of one population were found growing along roadside and are threatened by increased anthropogenic pressure causing habitat loss (tree felling and road widening activities).The EOO (Extent of Occurrence) and AOO (Area of Occupancy) is calculated using the online software GeoCAT, as 67.27 and 27 sq.km. respectively (AOO based on user defined cell width of 3 sqKm; Fig. 3 ). Thus, based on Criterion B following IUCN red list assessment guidelines ( IUCN 2019) Impatiens violoides is assessed as globally Endangered [B1+2ab(iii)].

Specimens examined:— INDIA, near Junglung , 8-7000 feet, 00.10.1844, M.P. Edgeworth 342 (K000694928!) ; Himachal Pradesh, Shimla District, Rohru sub-division, Chainsheel road, Larot , 12.08.2017, H.B. Naithani and Anup Chandra 5823 (DD!) ; Himachal Pradesh, Shimla District, Rohru sub-division, On way to Chanshal after crossing Larot village , 30.16877 N & 79.92510 E, 2800 m, 12.09.2023, Ashutosh Sharma 12585 (FRLH!) ; Himachal Pradesh, Shimla District, near Daranghati Wildlife Sanctuary, Kasha Pat forest , 3000 m, 10.09.2023, Ashutosh Sharma, 12584 (CAL!) ; Himachal Pradesh, Shimla District, Rohru sub-division, Janglikh forest , 2850 m, 12.09.2023, Ashutosh Sharma, 12586 (FRLH!) .

Discussion:— Impatiens violoides is a rare Western Himalayan endemic species characterised by its large white spurless flowers. The spurless character of flower is uncommon in Western Himalayan balsam species. For comparison, spurless species from Himalayas are Impatiens serrata Benth. ex Hook.f. & Thomson (1859:136) and I. kharensis S.Akiyama, H.Ohba & Wakab. (1991:75) having small/medium plant size upto 70 cm tall with white or yellow solitary flowers ( Akiyama et al. 1991, Akiyama 2021). Also I. williamsii H. Hara (1972:142) known from small area in western Nepal ( Sherpa et al. 2021) do not exceed 60 cm, has short racemose inflorescence with 1 to 3 yellow or purple flowers. Recently described I. glauca var. ecalcarata ( Singh et al. 2022) could be as big as I. violoides but has glaucous leaves with crenate or undulate margins and inflorescences with no more than eight flowers. The discussed species based on its most often racemose inflorescence and shape of capsule can be provisionally assigned to section Racemosae ( Yu et al. 2016) .

Narrow endemism (steno-endemism) seems to be common in genus Impatiens ( Grey-Wilson 1980, Fischer 2004) and the reason for endemism is habitat requirements of majority of species and rapid diversification of the genus in recent geological time ( Janssens et al. 2009, Qin et al. 2023). Complete lack of observations or collections of I. violoides from other areas of Western Himalaya and Nepal, as well as presence of only single observation (eFloraofIndia) and one herbarium sheet of the species, apart from type collection and our herbarium material (see Specimens examined) confirm the status of discussed species as rare and steno-endemic. The reason for restricted distribution of this species in a single valley can be attributed to two factors, first its geographical position ( Fig 3 ) as the species habitats are surrounded by high Himalayan mountain range (4000 metres and above) on the three sides thus making dispersal of genetic material difficult to the other side of high mountain ranges and secondly it may have evolved more recently, thus can also be considered as a neo-endemic species.

Figures

FIGURE 1. Impatiens violoides: A–B—Flowering plant habit; C—Flowering twig showing variation in type of inflorescence; D—Basal portion of main stem showing swollen nodes.

FIGURE 2. Impatiens violoides: A—Flower front view; B—Flower back view; C—Flower side view; D—Flower bud; E—Mature raceme inflorescence showing capsules; F—Lateral united petals (adaxial); G—Dorsal petal (abaxial); H—Lateral sepal (abaxial); I— Androecium covering gynoecium; J—Lower sepal; K—Glands at the base of petiole; L—Seed.

FIGURE 3. Distribution of I. violoides showing Extent of Occurrence (EOO) and Area of Occupancy (AOO). A—Kasha Pat (Daranghati Wildlife Sanctuary); B—Type locality (Between Pekha and Janglikh) and C (Larot, below Chanshal Pass). Made using Google Earth Pro and GeoCAT Kew. https://geocat.kew.org/editor.