Tag:

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.

Ericaceae

Rhododendron niveum

by GP Jürgens

Hook. f.

Sikkim2003 473 P655
Sikkim Lachung Valley 3100m August
Sikkim2004 409 P699
Sikkim Lachung Valley 3500m May
Sikkim2004 407 P697
Sikkim Lachung Valley 350

Description

Rhododendron niveum is a narrowly distributed eastern Himalayan species native to the Sikkim region of India, with extensions into adjacent China and Bhutan; its 92 georeferenced records, supplemented by occurrences in cultivation in Britain, Sweden, North America and Canada, reflect both a restricted wild range and its prominence in horticulture. It is a shrub or small tree of subalpine forest, rhododendron thickets and open hillsides near the treeline. The populations documented in the Lachung Valley of northern Sikkim between about 3100 and 3500 m, flowering in May and persisting in August, exemplify its high-montane habitat on cool, moist, acidic slopes.

The plant forms a compact tree or large shrub with stout branches. The leaves are obovate-elliptic, leathery and dark green above, their lower surface coated with a dense, persistent, silvery-white to fawn indumentum, the snowy tomentum that gives the species its epithet niveum. The flowers are grouped in dense, rounded terminal trusses; the campanulate corolla is a distinctive smoky lilac to deep purplish-mauve, a colour unusual among Himalayan rhododendrons, with ten stamens and a smooth, elongate ovary. The fruit is a woody, septicidal capsule releasing numerous minute seeds.

Within the vast genus Rhododendron, R. niveum belongs to subsection Arborea and is prized horticulturally for its striking flower colour and felted foliage, having been introduced by J. D. Hooker. Its restricted distribution and dependence on a narrow subalpine belt render it locally vulnerable to habitat loss, grazing and climatic shifts at the treeline, and it is of conservation interest as an eastern Himalayan near-endemic.

Author: Hook. f. · Sources: POWO (Kew), GBIF, Flora of Bhutan, Flora of China, The Rhododendron Handbook (RHS), Cox & Cox's The Encyclopedia of Rhododendron Species

Ericaceae

Rhododendron pendulum

by GP Jürgens

Hook. f.

Bhutan2014 338
Bhutan Tumching-La 3000m, May
Bh2008 236 P373
Bhutan Tumching-La, 3500m April

Description

Rhododendron pendulum is an epiphytic or epilithic dwarf shrub of the humid Eastern Himalaya, with verified occurrences in China, India, Bhutan and Nepal (further GBIF records from Britain and the United States represent cultivated stock). It is most characteristic of cool, mist-laden temperate forest, where it perches on mossy trunks, branches and rock faces, generally between about 2700 and 3700 m. The Bhutanese material illustrated, from the Tumching-La between roughly 3000 and 3500 m in April and May, captures the species in flower at the close of the cold season in its typical cloud-forest setting.

It is a small, straggling shrub with thin, often pendulous branches densely clothed, like the young growth and leaf undersides, in a soft rusty-brown woolly indumentum. The small, elliptic to oblong leaves are leathery, with revolute margins, dark green and somewhat rugose above and thickly tawny-tomentose beneath. The flowers are borne few together at the branch tips; the corolla is broadly campanulate to rotate, white sometimes flushed pink, and comparatively large for so diminutive a plant. The fruit is a small ovoid capsule that splits septicidally to shed numerous minute seeds adapted to dispersal in the canopy.

Rhododendron pendulum belongs to subgenus Rhododendron, section Pogonanthum and its allies, distinguished by its woolly indumentum and epiphytic habit, and was described by J.D. Hooker from his Sikkim explorations. Its dependence on permanently humid, moss-rich forest makes it a sensitive indicator of intact cloud-forest conditions, and although not presently regarded as threatened, it is vulnerable to forest degradation and to disruption of the orographic mist regime on which its epiphytic lifestyle depends.

Author: Hook. f. · Sources: POWO (Kew), GBIF, Flora of Bhutan, The Genus Rhododendron (Royal Botanic Garden Edinburgh), Flora of China

Ericaceae

Rhododendron setosum

by GP Jürgens

D. Don

BhutanPG2011 242
Bhutan Tsochenchen 3800m June
BhutanPG2011 550 01 scaled
Bhutan Tsochenchen 3800m June, see also: Cassiope fastigiata
Bh09 6 P8
Bhutan Chele-La 3950m June

Description

Rhododendron setosum is a high-alpine dwarf shrub distributed through the eastern and central Himalaya, recorded from Nepal, India (Sikkim), Bhutan, and southern Tibet (China), with 507 georeferenced occurrences confirming a continuous arc along the main range. It is a characteristic plant of the upper alpine zone, forming low cushions and open mats on exposed ridges, moraines and the margins of dwarf-rhododendron heath, frequently above the treeline between about 3500 and 5000 m. It was photographed at Tsochenchen, Bhutan, at 3800 m in June and on the Chele-La pass at 3950 m, where it grows alongside Cassiope fastigiata in cold, peaty acidic substrates exposed to strong insolation and wind.

It is a much-branched, prostrate to ascending evergreen shrublet rarely exceeding 30 cm, the young shoots densely setose with stiff bristly hairs and gland-tipped trichomes that give the plant a strongly aromatic resinous scent. The small leaves are elliptic to oblong, leathery, glandular-scaly (lepidote) on both surfaces and bristly-margined, crowded toward the branch tips. The flowers, borne in small terminal clusters, are broadly campanulate to funnel-shaped and a vivid pink-purple to magenta, with a setose, glandular calyx and exserted stamens. The fruit is a small ovoid septicidal capsule.

The species belongs to Rhododendron subgenus Rhododendron, section Pogonanthum, a group of aromatic small-leaved lepidote rhododendrons centred on the Sino-Himalaya. Its glandular indumentum and powerful scent are diagnostic within this section. Ecologically it is a pioneer of disturbed alpine ground and a component of dwarf-shrub heath, tolerant of frost and intense radiation. Though locally abundant and not threatened, populations are sensitive to grazing and warming-driven shifts of the treeline.

Author: D. Don · Sources: POWO (Kew), GBIF, Flora of Bhutan, Flora of China, The Genus Rhododendron (Cullen & Chamberlain monograph)

Ericaceae

Rhododendron thomsonii

by GP Jürgens

Hook. f.

Bhutan2014 631
Bhutan Phobjika 2800m, May
Bhutan2014 632
Bhutan Phobjika 2800m, May
Bhutan2014 382
Bhutan Tongsa 2000m, May
Sikkim2004 307 P542
Sikkim/India May

Description

Rhododendron thomsonii is an Eastern Himalayan endemic centred on Sikkim, Bhutan, adjacent northeastern India, southern Tibet (China) and easternmost Nepal, with the nearly 479 records also reflecting widespread cultivation in Britain, North America and continental Europe. In its native range it occupies the cool, humid temperate forest zone, the images documenting plants at Phobjika around 2800 m and Tongsa near 2000 m in Bhutan, flowering in May, together with material from Sikkim. It grows in fir and mixed broadleaved forest, on forest margins, in rhododendron thickets and on open rocky slopes between roughly 3000 and 4000 m, often where the monsoon brings high atmospheric humidity.

It is an evergreen shrub or small tree reaching several metres, with smooth, flaking reddish-brown to plum bark. The leaves are broadly obovate to orbicular, glabrous, glaucous beneath, rounded or emarginate at the apex and cordate at the base, borne on short petioles. The inflorescence is a loose terminal truss of few flowers; the corolla is fleshy, broadly campanulate and a deep blood-red to crimson, subtended by a large, cup-shaped, persistent and conspicuously coloured calyx that is diagnostic for the species. Stamens are ten; the ovary and curved style are glabrous, maturing into a woody capsule.

The species was described by J.D. Hooker from his Sikkim Himalayan expeditions and is the type of subsection Thomsonia within Rhododendron subgenus Hymenanthes. Its large fleshy calyx, glaucous foliage and waxy red bells distinguish it from related taxa and have made it a foundation species in horticultural breeding. Though restricted in distribution, it is locally common within suitable montane forest and is buffered by extensive cultivation, so it is not regarded as globally threatened, although habitat pressures affect parts of its native range.

Author: Hook. f. · Sources: POWO (Kew), GBIF, Flora of Bhutan, Flora of China, The Genus Rhododendron (Royal Botanic Garden Edinburgh)

Ericaceae

Rhododendron trichocladum

by GP Jürgens

Franch.

Sikkim2011 211
Sikkim Yumthang 3500m, June
Sikkim2011 213
Sikkim Yumthang 3500m, June
Sikkim2011 218
Sikkim Yumthang 3500m, June

Description

Rhododendron trichocladum is a deciduous, scaly-leaved shrub of the eastern Himalaya and adjacent Sino-Himalayan ranges, distributed across south-western China (notably Yunnan and south-eastern Tibet), northern Myanmar and the Indian Himalaya, with GBIF records (553 occurrences) confirming a centre of abundance in Sikkim, Yunnan and Upper Myanmar. It occupies open hillsides, forest margins, rhododendron thickets and rocky slopes at roughly 2700-4000 m, frequently in cool, humid, moss-rich montane settings. The photographed plant from the Yumthang valley in north Sikkim at about 3500 m in June typifies its preferred sub-alpine zone, where it flowers as the snow recedes alongside dwarf rhododendrons and primulas.

A much-branched shrub usually 0.5-1.5 m tall, with thin, often bristly young shoots bearing scattered scales and setae. The thin, deciduous leaves are obovate to elliptic, bright green, sparsely scaly above and densely lepidote beneath, with ciliate margins and a short petiole. Flowers are borne in small terminal clusters of one to three, opening with or before the leaves; the widely funnel-campanulate corolla is yellow, often greenish-yellow and sometimes faintly spotted, with five lobes and a scaly outer surface. Stamens ten, declinate; the ovary is densely scaly, tapering into a slender style. The fruit is a small, ovoid, scaly capsule dehiscing septicidally to release minute winged seeds.

The species belongs to Rhododendron subsection Trichoclada (subgenus Rhododendron), a small group of deciduous, yellow-flowered, scaly-leaved shrubs characterised by their bristly indumentum. It is a valuable subject for cool temperate woodland gardens and has contributed to horticultural breeding. Though not globally threatened given its broad Sino-Himalayan range, populations are locally dependent on undisturbed sub-alpine scrub, making them sensitive to grazing pressure, fuelwood collection and habitat shifts driven by warming climates.

Author: Franch. · Sources: POWO (Kew), GBIF, Flora of China, Flora of Bhutan, The Genus Rhododendron (Royal Horticultural Society monograph)

Ericaceae

Rhododendron wightii

by GP Jürgens

Hook. f.

Sikkim2011 290
Sikkim Lada-La 3950m, June
Bh2008 257 G404
Bhutan Tumching-La, 3750m April
Bh2008 591 P884
Bhutan Tumching-La, 3750m April
Bh2008 592 P885
Bhutan Chele-La, 3850m April
Sikkim2004 224 P383
Sikkim/India Singalila 4000m May

Description

Rhododendron wightii is an Eastern Himalayan shrub or small tree ranging from eastern Nepal through Sikkim and northern West Bengal into Bhutan and adjoining southern Tibet (China), with GBIF recording 251 occurrences over IN, NP, CN and BT alongside cultivated records from Britain and elsewhere. It is a constituent of the upper temperate to subalpine zone, growing in rhododendron thickets, at the forest limit and among open hillsides between about 3300 and 4300 m. The photographed populations span Sikkim (Lada-La 3950 m, June; Singalila 4000 m, May) and Bhutan (Tumching-La 3750 m and Chele-La 3850 m, April), documenting its spring to early-summer flowering.

It is an evergreen shrub to small tree with stout branches. The leaves are leathery, elliptic to obovate, dark green and glabrous above, and conspicuously coated beneath with a dense, suede-like, fawn to rust-coloured indumentum of agglutinate hairs that is diagnostic. The flowers are grouped in lax, one-sided terminal trusses; each campanulate corolla is pale yellow to creamy-yellow, often marked with a crimson basal blotch, and has five lobes. The androecium of ten stamens surrounds a superior ovary topped by a long style, and the fruit is a curved, woody, septicidal capsule releasing numerous small seeds.

Within the genus, R. wightii belongs to subgenus Hymenanthes (the elepidote rhododendrons), allied to the Taliensia group and characterised by its yellow flowers and thick leaf indumentum. Named for the botanist Robert Wight, it is valued in horticulture for hardiness and foliage. Its dwarf-rhododendron habitat is locally extensive, but high-altitude shrublands face pressure from grazing, burning and a warming climate.

Author: Hook. f. · Sources: POWO (Kew), GBIF, Flora of Bhutan, The Genus Rhododendron (Cullen & Chamberlain, Edinburgh), Hooker's Rhododendrons of the Sikkim-Himalaya

Grossulariaceae

Ribes griffithii

by GP Jürgens

Hook. f. & Thomson

Sikkim2011 366
Sikkim Lada-La 3900m, June

Description

Ribes griffithii is a Sino-Himalayan currant of high-elevation shrubberies, distributed through China, Nepal, Bhutan and India (with a few scattered extralimital records); GBIF lists 277 occurrences, the great majority along the Himalayan and Tibetan margins. It occupies subalpine forest edges, Rhododendron and juniper scrub, moist rocky slopes and streamside thickets, generally between about 3000 and 4000 m. The illustrated plant was recorded in Sikkim near Lada-La at 3900 m in June, a characteristic upper-montane to subalpine station where the shrub leafs out and flowers as the snow recedes.

The plant is a deciduous, unarmed shrub with arching to ascending branches and smooth or flaking bark. Leaves are alternate, palmately three- to five-lobed with a cordate base and a serrate to crenate-dentate margin, glabrescent to slightly pubescent and borne on slender petioles. The flowers are arranged in pendulous, many-flowered racemes; each is small, with a saucer-shaped to shallowly campanulate hypanthium, five reflexed greenish to reddish sepals, five smaller petals, five stamens and an inferior ovary. The fruit is a glabrous, ellipsoid to globose berry, reddening to dark red at maturity and crowned by the persistent perianth.

The species belongs to subgenus Ribes among the unarmed true currants, distinguished from the spiny gooseberries by its racemose, many-flowered inflorescences. POWO and GBIF accept the name. As a fleshy-fruited shrub it contributes to the diet of Himalayan birds and small mammals that disperse its seeds across the subalpine mosaic.

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

Grossulariaceae

Ribes luridum

by GP Jürgens

Hook. f. & Thomson

Bhutan2014 606
BhutanPhobjika 2810, May
Sikkim2011 76
Sikkim Tanghu 3900m, June

Description

Ribes luridum is a Sino-Himalayan currant distributed from south-western China through northern Myanmar, Nepal, northern India and Bhutan, with around 348 GBIF occurrences (the records from US, CA, PL and RU largely representing cultivated or herbarium material). It is a shrub of cool-temperate to subalpine forest, scrub margins and rocky slopes, typically between about 2800 and 4000 m. The collections from Phobjika in Bhutan at 2810 m in May and from Tanghu in Sikkim at 3900 m in June bracket this altitudinal range and its late-spring to early-summer flowering, on moist, humus-rich ground at and above the upper forest belt.

It is a deciduous, unarmed shrub with spreading branches and finely glandular young growth. The leaves are alternate, orbicular-cordate in outline and palmately three- to five-lobed, the lobes crenate-serrate, sparsely pubescent and often glandular beneath. The species is dioecious or functionally so, the small flowers borne in short, few-flowered, pendulous racemes; each has a saucer-shaped to shortly campanulate hypanthium and five small, dull purplish to lurid greenish-brown petals and sepals, the colouration alluded to by the epithet. The fruit is a small subglobose berry, glandular-bristly and reddish to dark purple when ripe.

Within Ribes the species sits in the section of unarmed currants and is distinguished by its dingy, glandular flowers and dioecious tendency. The pendulous berries are dispersed by frugivorous birds, an important agent in fragmented montane forest, while the inconspicuous flowers attract small bees and flies. The species is widespread across the eastern Himalaya and faces no recognised conservation threat.

Author: Hook. f. & Thomson · Sources: POWO (Kew), GBIF, Flora of China Vol. 8, Flora of Bhutan Vol. 1, Flora of Nepal, A Monograph of the Genus Ribes

Grossulariaceae

Ribes takare

by GP Jürgens

D. Don

Sikkim2011 365
Sikkim Lada-La 3900m, June
Bh2008 12 P20
Bhutan Thimphu-Chu, 2750m April
Sikkim2004 62 P110
Sikkim West-Bengal, Bersay 2700m April
Sikkim 2006 30 ergebnis
India West-Bengal Tonglu 3150m, May

Description

Ribes takare is a Himalayan currant distributed along the temperate and subalpine belt from Afghanistan through Pakistan, Nepal, India and Bhutan into southwestern China and Myanmar, with GBIF recording close to a thousand occurrences across this arc. It grows in moist temperate and upper montane forest, forest margins, shrubberies, ravines and rocky slopes, typically between about 2500 and 4000 m. The image caption documents this range well, with collections from the Lada La in Sikkim at 3900 m in June, the Thimphu Chu in Bhutan at 2750 m in April, Bersay in West Bengal at 2700 m in April, and Tonglu at 3150 m in May, showing both its broad altitudinal span and its spring-to-early-summer flowering as the snowline retreats.

It is a deciduous, spineless (unarmed) shrub up to about 2-3 m tall, with greyish, peeling bark and glandular-pubescent young shoots. The leaves are alternate, palmately three- to five-lobed with crenate-serrate margins and a cordate base, somewhat resembling a maple leaf and often glandular-hairy beneath. The flowers are borne in many-flowered, pendulous racemes; they are small and reddish to purplish-brown, with a saucer-shaped to shallowly campanulate hypanthium, five reflexed sepals, five smaller petals, five stamens and an inferior ovary. The fruit is a glandular-bristly, reddish to purplish-black berry that is edible but rather acidic and somewhat resinous.

The genus Ribes, sole genus of Grossulariaceae, is well represented in the Himalaya, where R. takare belongs to the unarmed, raceme-flowered black-currant alliance and has been treated under synonyms including R. acuminatum and R. glaciale-related names by various authors. Its pendent racemes of nectariferous flowers attract bees and other insects, while the berries are dispersed by birds and small mammals; the species forms an understorey component of moist Himalayan forest. It is widespread and common across its extensive range and is of no conservation concern, while its acidic fruits are gathered locally and its hardiness has drawn modest horticultural interest.

Author: D. Don · Sources: POWO (Kew), GBIF, Flora of China Vol. 8, Flora of Bhutan Vol. 1, Flora of Nepal, Flora of Pakistan, Berger's taxonomic review of Ribes

Zingiberacaea

Roscoea auriculata

by GP Jürgens

K.Schum.

Sikkim2003 49 W68
Sikkim above Yoksam 2200m 08.2003
Nepal 99 909 ergebnis
West-Nepal Hanke 2700m, July

Description

Roscoea auriculata is an eastern Himalayan terrestrial ginger recorded from India, China, Nepal and Bhutan across some 126 GBIF occurrences. The photographed plants were found above Yoksam in Sikkim at 2200 m in August and at Hanke in West Nepal at 2700 m in July, locations typical of its range in moist temperate forest glades, grassy banks and open slopes between roughly 2000 and 3000 m. Unlike most members of the predominantly tropical Zingiberaceae, Roscoea is adapted to cool montane conditions, dying back to a tuberous rootstock to overwinter and emerging with the summer monsoon.

The plant is an erect perennial herb arising from clustered fleshy, tuberous roots. The leaves are few, lanceolate and arranged distichously, their sheaths forming a false stem (pseudostem); the diagnostic feature signalled by the epithet is the conspicuously auriculate leaf-sheath base. The flowers are large, showy and orchid-like, deep violet to purple, emerging successively from a terminal cluster; each has a hooded dorsal corolla lobe, two erect lateral staminode-like structures and a broad, often bilobed reflexed labellum, with a single fertile stamen.

Note that the input family is given as "Zingiberacaea", an evident misspelling of Zingiberaceae, in which Roscoea is correctly placed. The genus is celebrated for its convergence on an orchid-like floral form, an adaptation for pollination by long-tongued bees, and is much prized in cultivation for hardy temperate gardens. R. auriculata has a relatively restricted eastern Himalayan distribution; though not formally threatened, it is locally collected and sensitive to habitat disturbance.

Author: K.Schum. · Sources: POWO (Kew), GBIF, Flora of Bhutan, Flora of Nepal, Flora of China, Cowley – The Genus Roscoea (Royal Botanic Gardens Kew monograph)