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Sikkim

Flowers of Sikkim — 350 species from the Sikkim Himalaya in northeast India, a compact yet botanically extraordinary region that climbs from subtropical valleys to the alpine zone beneath Kangchenjunga. Sikkim is a classic centre of Himalayan plant diversity, celebrated for its rhododendrons, primulas, orchids and gentians. Each entry provides a botanical description, distribution, habitat and flowering season with the original field photograph.

Primulaceae

Bryocarpum himalaicum

by GP Jürgens

Hook.f. & Thomson

Bhutan2014 497
Bhutan Phobjika 2800m, May
Bhutan2014 499
Bhutan Phobjika 2800m, May

Description

Bryocarpum himalaicum is the sole species of its genus, a primuloid herb endemic to the eastern Himalaya and recorded from Bhutan, India (Sikkim), Nepal and southern China; GBIF documents around 86 occurrences across this narrow range. It grows in moss-rich, humus-laden ground in cool, shaded forest, among rhododendron and bamboo thickets and on damp, mossy banks in the upper temperate and subalpine zones, typically between about 2700 and 3700 m. The illustrated plant from Phobjika in central Bhutan at 2800 m, flowering in May, is characteristic of these humid, sheltered montane habitats.

It is a small, delicate perennial herb arising from a slender rhizome, forming a rosette of long-petioled, ovate to cordate, crenate leaves with a soft texture. The flowers are solitary and nodding on slender scapes, the corolla being narrowly tubular to bell-shaped and clear yellow, with a slender tube expanding into five spreading lobes, evoking a miniature pendent primrose. A distinctive feature giving the genus its name is the elongate, beaked, septicidal capsule that buries or lowers itself among the moss as it matures before releasing the seeds.

Bryocarpum is a monotypic genus traditionally allied to Primula and the cyclamenoid primulas within Primulaceae, distinguished by its solitary yellow flowers and peculiar elongate fruiting capsule. Its restricted high-Himalayan range and dependence on undisturbed mossy forest floor make it a botanically significant relict of conservation interest, vulnerable to habitat disturbance and changing montane moisture regimes.

Author: Hook.f. & Thomson · Sources: POWO (Kew), GBIF, Flora of Bhutan, Flora of China, Primula (J. Richards monograph)

Orchideaceae

Bulbophyllum affine

by GP Jürgens

Lindl.

Bh09 392 G619
Bhutan Mo-Chu, 1500m June

Description

Bulbophyllum affine is an epiphytic orchid widely distributed across East and Southeast Asia, from Nepal and northeast India (Sikkim, Assam) through Bhutan, Myanmar, and southern China to Taiwan, Vietnam, and Thailand. It inhabits humid broadleaved and mixed forests at 500–2,500 m elevation, growing on mossy trunks and branches, occasionally on rocks (lithophytic).

The plant produces ovoid to conical pseudobulbs 2–4 cm tall, set 3–8 cm apart on a stout, creeping rhizome. Each pseudobulb bears a single, leathery, elliptic to oblong leaf 8–15 cm long. The inflorescence is a nodding, densely many-flowered raceme 5–15 cm long, emerging from the base of the pseudobulb. The flowers are small, 5–8 mm across, yellowish-green to pale brown, densely arranged in a cylindrical spike. Sepals are lanceolate and acuminate; the lip is small, fleshy, and recurved, mobile on a thin strap connecting it to the column foot — a characteristic feature of Bulbophyllum enabling pollination by small flies.

Bulbophyllum is the largest genus in the Orchidaceae, comprising over 2,200 described species. B. affine belongs to section Cirrhopetalum and is distinguished from similar congeners by its densely flowered, cylindrical raceme and the prominent column stelidia.

Author: Lindl. · Sources: POWO (Kew), Flora of Bhutan Vol. 3, GBIF, Seidenfaden: Orchid Genera in Thailand XIV: Bulbophyllum (1979)

Orchideaceae

Bulbophyllum striatum

by GP Jürgens

Rchb.f.

Bhutan2012 1351
Bhutan Yankel 400m, October

Description

Bulbophyllum striatum is an epiphytic orchid confined to the eastern Himalayas and adjacent regions, with documented occurrences in northeast India (Sikkim, Assam, Meghalaya), Bhutan, Nepal, Bangladesh, and southwest China (Yunnan). It inhabits warm, humid subtropical and tropical forests at low to moderate elevations of 200–1,500 m — among the lower-altitude Bulbophyllum species in the Himalayan flora.

The pseudobulbs are ovoid, 2–3 cm tall, set at intervals on a stout, creeping rhizome. Each bears a single, oblong-lanceolate, coriaceous leaf 10–18 cm long. The inflorescence is an arching to pendent, laxly few-flowered raceme, 8–15 cm long, producing 3–8 flowers. The specific epithet 'striatum' (striped) refers to the conspicuous reddish-brown longitudinal striations on the sepals: flowers are 1.5–2 cm across, yellowish-green with prominent dark reddish-brown veining. The lip is dark purple, fleshy, curved, and mobile on the column foot. Flowering occurs from September to November.

The relatively low-altitude habitat of B. striatum at Yankel (400 m) in southern Bhutan reflects the warm, subtropical character of the Mo-Chu and lower Punatsangchu valleys, which harbour a distinct orchid flora adapted to high humidity and temperatures atypical for most of Bhutan.

Author: Rchb.f. · Sources: POWO (Kew), Flora of Bhutan Vol. 3, GBIF, Pearce & Cribb: The Orchids of Bhutan (2002)

Orchideaceae

Bulbophyllum yoksunense

by GP Jürgens

J.J.Sm.

Bhutan2012 1178
Bhutan Tashiyangtse 2000m, October
Bhutan2012 1180
Bhutan Tashiyangtse 2000m, October
Bhutan2012 1181
Bhutan Tashiyangtse 2000m, October

Description

Bulbophyllum yoksunense is a rare epiphytic orchid with a restricted distribution in the eastern Himalayas. The species is named after Yuksom (also spelled Yoksum or Yoksun) in western Sikkim, India, where the type specimen was collected. Its known range includes Sikkim, Bhutan, eastern Nepal, and northern Myanmar. With only 17 documented occurrences in GBIF, it is among the less frequently recorded Bulbophyllum species in the region. It grows on mossy tree trunks in temperate broadleaved forests at 1,500–2,500 m elevation.

The pseudobulbs are ovoid, 1–2 cm tall, closely set on a creeping rhizome. Each bears a single, elliptic, coriaceous leaf 5–10 cm long. The inflorescence is a short, few-flowered raceme. Flowers are small, about 8–12 mm across, with distinctive coloration: the sepals are pale greenish-yellow with fine purple veining, and the lip is dark purple, fleshy, and slightly recurved. The lateral sepals are slightly longer than the dorsal sepal. Flowering in Bhutan occurs in October.

B. yoksunense is poorly known in cultivation and in the wild. Its apparent rarity may partly reflect under-collection in the remote eastern Himalayan forests of Bhutan and Sikkim. Further field survey is needed to clarify its true distribution and conservation status.

Author: J.J.Sm. · Sources: POWO (Kew), GBIF, Pearce & Cribb: The Orchids of Bhutan (2002), J.J. Smith: Orchidaceae Novae (1910)

Orchideaceae

Calanthe biloba

by GP Jürgens

Lindl.

Bhutan2012 689
Bhutan Galephu 850m, September

Description

Calanthe biloba is a terrestrial orchid native to the eastern Himalayas and adjacent regions, occurring in northeast India (Sikkim, Assam, Meghalaya), Bhutan, Nepal, southwest China (Yunnan), and northern Vietnam. It grows in the understory of warm, humid broadleaved forests and along shaded stream banks at 500–1,500 m elevation, in well-drained, humus-rich soils.

The plant produces prominent, conical pseudobulbs partially enclosed by the persistent leaf bases. The leaves are large, 30–50 cm long, broadly elliptic to obovate, plicate (folded lengthwise), and deciduous in the dry season. The inflorescence is an erect, pubescent raceme 30–60 cm tall, bearing 10–20 flowers. Flowers are 2.5–3.5 cm across, white to pale yellow. The lip is conspicuously bilobed (as the specific epithet indicates), with two diverging apical lobes, and bears a yellow callus of raised lamellae. The spur is slender, 1.5–2 cm long. Flowering occurs from August to October.

Calanthe biloba belongs to the deciduous group of Calanthe (subgenus Preptanthe), which shed their leaves before or during flowering. The relatively low elevation of the collecting locality at Galephu (850 m) reflects southern Bhutan's subtropical climate, where several thermophilic orchid species reach their northern distributional limit.

Author: Lindl. · Sources: POWO (Kew), Flora of Bhutan Vol. 3, GBIF, Pearce & Cribb: The Orchids of Bhutan (2002)

Orchideaceae

Calanthe chloroleuca

by GP Jürgens

Lindl.

Nepal 97 299 P600
Nepal new Clepua 2370m May
Nepal 97 301 G602
Nepal new Clepua 2370m May
Nepal 2001 147 ergebnis ergebnis
East-Nepal Bhalukhop 2520m, April

Description

Calanthe chloroleuca is a terrestrial orchid of restricted distribution in the eastern Himalayas, known from Nepal, northeast India (Sikkim), Bhutan, and southwest China (Yunnan). With fewer than 20 documented occurrences in GBIF, it is one of the rarer Calanthe species in the region. The species grows in moist, shaded forest understory, on humus-rich soils among leaf litter, at elevations of 2,000–3,000 m.

The plant is an evergreen species with reduced pseudobulbs hidden by leaf bases. It produces 3–5 elliptic, plicate leaves 15–25 cm long. The inflorescence is an erect raceme 20–40 cm tall, carrying 8–15 flowers. The name 'chloroleuca' derives from Greek chloros (green) and leukos (white), accurately describing the flower coloration: sepals and petals are greenish-white, and the lip is white with a greenish or yellowish tinge, trilobed, with low, parallel keels on the disc. The spur is slender, 1–1.5 cm long, slightly curved. Flowering occurs from April to May.

Calanthe chloroleuca is easily confused with the similarly coloured C. brevicornu, from which it differs in its longer spur, narrower lip lobes, and more elongated floral bracts. Its rarity in herbarium collections may partly reflect the difficulty of distinguishing it from congeners in the field.

Author: Lindl. · Sources: POWO (Kew), Flora of Nepal Checklist, GBIF, Flora of Bhutan Vol. 3

Calceolaraceae

Calceolaria tripartita

by GP Jürgens

Ruiz & Pav.

Sikkim2003 57 G76 ergebnis
Sikkim above Yoksam 2750m 08.2003
Sikkim2003 58 P78 ergebnis
Sikkim above Yoksam 2750m 08.2003

Description

Calceolaria tripartita is a Neotropical annual herb native to the Andean region of South and Central America, its GBIF distribution centred on Ecuador, Peru, Bolivia, Colombia, Brazil and adjacent countries, but it has become a widespread weed of warm-temperate uplands and is now naturalised in New Zealand, Australia, Sri Lanka, Indonesia and parts of the Himalaya. It colonises moist, disturbed ground, streamsides, cultivated land, ditches and roadside banks. The photographed plant from above Yoksam in Sikkim at around 2750 m, recorded in August, documents this naturalised Himalayan occurrence, where the monsoon-moistened, disturbed montane habitat closely mirrors its native ecology.

The plant is a slender, erect, glandular-pubescent annual with branched, somewhat succulent stems. The leaves are opposite, the lower often pinnately three-parted (whence tripartita) into toothed segments, the upper smaller. The flowers are borne in lax terminal cymes and display the distinctive Calceolaria form: a strongly two-lipped, yellow, slipper- or pouch-shaped corolla, the small upper lip and the inflated, saccate lower lip enclosing the two stamens. The fruit is an ovoid, septicidal capsule releasing abundant minute, reticulate seeds well suited to wind and water dispersal.

The genus, the slipperworts, is now placed in its own family Calceolariaceae, formerly within the Scrophulariaceae. The pouched corolla is associated with specialised oil-collecting bee pollination in its native Andean range. As an aggressive colonist of disturbed ground, C. tripartita exemplifies a Neotropical weed that has crossed into Old World mountain systems through human agency; it is of no conservation concern and is, rather, regarded locally as an invasive.

Author: Ruiz & Pav. · Sources: POWO (Kew), GBIF, Flora of China Vol. 18, Flora of Nepal, A Revision of the Genus Calceolaria (Calceolariaceae), Flora of Ecuador

Ranunculaceae

Caltha scaposa

by GP Jürgens

Hook.f. & Thomson

BhutanPG2011 448
Bhutan Ludlow-Sherriff-Trail Warrtlang-La, 4500m June
Sikkim2003 105 P143
Sikkim below Dzongri 3850m 08.2003
Nepal 2001 312 ergebnis ergebnis
Nepal (Gorkha) Kharka 3100m, May

Description

Caltha scaposa is a high-alpine marsh marigold of the Sino-Himalayan region, with records from China, India, Nepal, Bhutan and Myanmar and disjunct documentation in Korea and Mongolia; GBIF aggregates over 1,000 occurrences. It is a plant of wet alpine turf, snowmelt flushes, streamsides and moist gravelly meadows, typically between roughly 3,100 and 4,500 m. The collections illustrated span this gradient, from Warrtlang-La on the Ludlow-Sherriff trail in Bhutan at about 4,500 m in June, to the slopes below Dzongri in Sikkim near 3,850 m, and a comparatively low Gorkha station in Nepal at 3,100 m in May, where it flowers as the snow recedes.

It is a small, glabrous, somewhat fleshy perennial herb arising from a short, fibrous-rooted rhizome. The leaves are largely basal and long-petiolate, with cordate to reniform-orbicular blades bearing crenate margins and a deep cordate sinus. The flowering stem is scapose, as the epithet indicates, usually leafless and bearing a solitary terminal flower. The showy perianth consists of five to several petaloid, golden-yellow sepals, true petals being absent; the numerous stamens surround a cluster of free, sessile carpels. The fruit is an aggregate of spreading, beaked follicles dehiscing along the ventral suture.

Within Caltha, the scapose habit and solitary flower distinguish C. scaposa from the leafy-stemmed, multiflowered C. palustris group. As an obligate wetland species of the alpine zone, it indicates permanently moist soils and is pollinated chiefly by flies and early-season insects. Though locally common across a wide range and not presently considered threatened, its dependence on snowmelt hydrology makes populations sensitive to glacial retreat and altered precipitation in a warming Himalaya.

Author: Hook.f. & Thomson · Sources: POWO (Kew), GBIF, Flora of China, Flora of Bhutan, Annotated Checklist of the Flowering Plants of Nepal, Tamura's monograph of Ranunculaceae

Campanulaceae

Campanula pallida

by GP Jürgens

Wall.

Bhutan2012 188
Bhutan Haar-Valley, 3300m September
Bhutan2012 313
Bhutan Haar-Valley, 3300m September
Sikkim2003 381 P537
Sikkim Tista valley 3300m August

Description

Campanula pallida is a widespread Asian bellflower with an extensive GBIF record (over 68,000 occurrences) centred on China, India, Nepal, Pakistan, Bhutan and Afghanistan, with numerous further reports across the broader range from Myanmar and Thailand to scattered cultivated and recorded localities elsewhere. It is a plant of open, well-drained ground, frequenting grassy slopes, rocky banks, terrace margins, roadside cuttings and forest clearings in the temperate and subalpine zones, broadly between about 1500 and 3500 m. The plants illustrated from the Haa valley in Bhutan at 3300 m in September and the Tista valley in Sikkim at 3300 m in August reflect its long summer-to-autumn flowering across the eastern Himalaya.

The species is a perennial herb with slender, ascending to decumbent stems bearing scattered hairs and clear latex. The leaves are alternate, ovate to oblong-lanceolate, with a crenate to serrate margin, the lower leaves petiolate and the upper sessile. The flowers are nodding, borne singly or in a loose few-flowered inflorescence; the corolla is broadly campanulate, five-lobed and pale blue to lilac or sometimes whitish, with reflexed appendages between the calyx lobes. The five stamens have dilated filament bases, and the inferior ovary matures into a nodding capsule that dehisces by basal pores to shed numerous small seeds.

Campanula is a large and taxonomically difficult genus, and C. pallida belongs to a complex of variable Himalayan bellflowers in which flower size and indumentum vary geographically. The pendulous, protandrous flowers are pollinated principally by bees, and the pore-dehiscent capsule disperses seed by wind shaking. The species is abundant, ecologically tolerant and frequently associated with semi-disturbed ground, and it is of no conservation concern.

Author: Wall. · Sources: POWO (Kew), GBIF, Flora of China, Flora of Bhutan, Flora of Pakistan, Revision of the Asiatic Campanula (Kolakovsky)

Brassicaceae

Cardamine elegantula

by G & P Jürgens

Hook.f. & Thomson

Nepal 2001 87 ergebnis ergebnis
East-Nepal Gupka Pokhari 2920m, April

Description

Cardamine elegantula is an Eastern Himalayan species ranging from eastern Nepal through Sikkim and the northern West Bengal hills into Bhutan, with GBIF recording 17 occurrences across BT, NP and IN. It is a plant of cool, humid temperate forest, occurring on shaded, moss-covered banks, in damp ravines and along streamsides where the soil remains moist through the growing season. The photographed population was found in East Nepal at Gupka Pokhari near 2920 m, flowering in April, which is characteristic of its early-season anthesis at montane elevations broadly between 2500 and 3500 m.

The species is a slender, glabrous perennial herb arising from a thin rhizome, with erect to ascending, sparingly branched stems. The leaves are pinnately compound: the cauline leaves bear several pairs of ovate to lanceolate, toothed lateral leaflets and a larger terminal leaflet, the whole foliage delicate in texture. Flowers are borne in lax terminal racemes; each has four free sepals and four white to pale pink, clawed petals arranged in the cruciform pattern of the Brassicaceae, with the characteristic tetradynamous androecium of six stamens. The fruit is a slender, linear silique that dehisces elastically along two valves to disperse the small seeds in a single row.

Within Cardamine, a large cosmopolitan genus of bittercresses, C. elegantula belongs to the perennial, rhizomatous Himalayan element distinguished by its graceful habit, pinnate leaves and slender siliques. As a moisture-demanding forest understorey herb it serves as an indicator of intact, undisturbed temperate woodland. It has not been formally assessed for conservation status; its restricted Eastern Himalayan range makes it potentially sensitive to forest clearance and habitat desiccation.

Author: Hook.f. & Thomson · Sources: POWO (Kew), GBIF, Flora of Bhutan, Annotated Checklist of the Flowering Plants of Nepal, Flora of China (Brassicaceae)