Tag:

Bhutan

Flowers of Bhutan — 1326 plant species documented across the Bhutanese Himalaya, from dense broadleaf and conifer forests to alpine scrub and meadows. Bhutan’s largely intact wilderness shelters an exceptional diversity of orchids, rhododendrons, primulas and Himalayan poppies, many of them regional endemics. Each species page includes a botanical description, distribution, habitat and flowering time, with the original photograph and its recorded altitude and locality.

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 triflorum

by GP Jürgens

Hook. f.

Bhutan2014 357
Bhutan Tumching-La 3100m, May
Bhutan2014 402
Bhutan Yatong-La 2900m, May
Bhutan2014 403
Bhutan Yatong-La 2900m, May

Description

Rhododendron triflorum is an eastern Himalayan rhododendron distributed across China, Bhutan, India, Nepal and Myanmar, with about 484 GBIF occurrences (additional records abroad reflecting its popularity in cultivation). It grows in temperate forest, forest margins, rhododendron and conifer thickets and open shrubby slopes, generally between roughly 2700 and 3700 m. The plants photographed at Tumching-La (about 3100 m) and Yatong-La (about 2900 m) in Bhutan, both in May, exemplify its mid-montane forest habitat, where it flowers in late spring among mixed broad-leaved and coniferous woodland.

The species is an erect shrub or small tree with smooth, attractive coppery to reddish-brown, peeling bark. The leaves are evergreen, ovate to elliptic, glabrous above and conspicuously scaly (lepidote) beneath, the scales characteristic of the lepidote rhododendrons. The flowers are borne in small terminal clusters, typically in threes as the epithet triflorum indicates; the broadly funnel-campanulate corolla is pale yellow, often flushed or spotted with green, and densely scaly outside. There are ten stamens and a scaly ovary, and the fruit is a small dry capsule splitting to release numerous minute seeds.

Rhododendron triflorum belongs to subgenus Rhododendron (the lepidote, scaly-leaved rhododendrons), section Triflora, a group of slender-flowered species centred on the Sino-Himalaya. The lepidote indumentum and small capsular fruits with abundant wind-dispersed seed are characteristic of this clade. With a wide eastern Himalayan distribution the species is of least concern, and its handsome bark and yellow flowers have made it a valued ornamental; like its congeners it is an important component of the rhododendron-dominated temperate forests of the eastern Himalaya.

Author: Hook. f. · Sources: POWO (Kew), GBIF, Flora of China, Flora of Bhutan, Annotated Checklist of the Flowering Plants of Nepal, Cullen revision of lepidote Rhododendron

Ericaceae

Rhododendron tsariense

by GP Jürgens

Cowan

Bh2008 223 G352
Bhutan Tumching-La, 3800m April
Bh2008 224 P355
Bhutan Tumching-La, 3800m April
Bh09 339 G553
Bhutan Jakar 3700m April

Description

Rhododendron tsariense is a shrub of the eastern Himalaya, restricted to China (south-eastern Tibet), north-eastern India and Bhutan, with a small number of records (66 occurrences in GBIF) reflecting its limited range. It inhabits high subalpine and alpine zones, growing in open coniferous and Rhododendron scrub, on rocky slopes, ridges and the margins of fir forest, characteristically between about 3000 and 4300 m. The photographed plants come from Bhutan, at Tumching-La (3800 m) and near Jakar (3700 m), flowering in April as the high passes emerge from winter, an elevation typical of the species' montane habitat.

It is a compact, much-branched evergreen shrub, the young shoots and undersides of the leaves clothed in a dense, felted, fawn to rusty-brown indumentum that is one of its most diagnostic features. The leaves are small, leathery, elliptic to obovate, dark green and somewhat rugose above. The flowers are borne in small terminal trusses; the corolla is campanulate (bell-shaped), creamy white to pale pink, often flushed rose and spotted within. The fruit is a woody dehiscent capsule, the persistent style and calyx remaining at the apex.

The species belongs to subsection Lanata (subgenus Hymenanthes), a group of indumented eastern Himalayan rhododendrons characterised by their conspicuously hairy leaf undersurfaces. Named for the Tsari region, it is a narrow-range endemic of conservation interest, its alpine populations potentially sensitive to climate shifts and to grazing and burning pressure in the high pastures. Like other rhododendrons it is bee- and bird-pollinated and forms ericoid mycorrhizal associations adapted to acidic, peaty mountain soils.

Author: Cowan · Sources: POWO (Kew), GBIF, Flora of Bhutan, The Genus Rhododendron (Cowan & Davidian), Edinburgh Rhododendron revision

Ericaceae

Rhododendron vaccinioides

by GP Jürgens

Hook.

Bhutan2014 811
Bhutan Wangdi Mo-Chu 1600m, May
Nepal 97 108 P184
Nepal Dongen 2400m April
Nepal 1994 196 ergebnis
Ost-Nepal Mewa-Khola
2100m April

Description

Rhododendron vaccinioides is a small epiphytic rhododendron of the eastern Himalaya and adjacent China and Southeast Asia, recorded from China, India, Myanmar, Nepal, Bhutan, Vietnam and Japan, with some 245 GBIF occurrences. It grows as an epiphyte on mossy trunks and branches, and occasionally on rocks, in humid temperate broadleaved and conifer forest, generally between about 1600 and 3000 m. The documented populations span Wangdi Mo-Chu in Bhutan at 1600 m, Dongen in Nepal at 2400 m and the Mewa Khola in eastern Nepal at 2100 m, flowering in April and May in the cloud-bathed mid-montane belt.

It is a small, much-branched epiphytic shrub with slender, often pendent or sprawling branchlets bearing scattered scales (lepidote indumentum). The leaves are small, obovate to oblanceolate and somewhat fleshy, clustered toward the branch tips, vaccinium-like in aspect, hence the epithet, and lepidote beneath. The flowers are small, solitary or few at the branch ends, with a short-tubed, broadly funnelform to rotate, white to pinkish corolla that is sparsely scaly outside. The fruit is a small lepidote capsule splitting into valves to release numerous minute seeds adapted to wind dispersal among the canopy.

The species belongs to Rhododendron subgenus Rhododendron, section Vireya (the largely epiphytic, tropical-montane rhododendrons), of which it is one of the few representatives reaching the Himalaya. It is widespread and not threatened, but as an epiphyte dependent on humid, moss-laden old-growth forest it is sensitive to deforestation and to drying of the montane cloud belt.

Author: Hook. · Sources: POWO (Kew), GBIF, Flora of Bhutan, Flora of China, Argent monograph of Rhododendrons of Subgenus Vireya

Ericaceae

Rhododendron vaccinioides

by GP Jürgens

Hook. f.

Bhutan2014 43
Bhutan Trashigang 1300m, May
Bhutan2014 391
Bhutan Tumching-La 3000m, May
Bh2008 146 P243
Bhutan Chendebji, 2450m April

Description

Rhododendron vaccinioides Hook. f. is a small epiphytic rhododendron of the eastern Himalaya and adjacent montane Asia, ranging from Nepal and India through Bhutan to southern China, Myanmar and Vietnam, with around 245 GBIF occurrences. It grows characteristically as an epiphyte on mossy trunks and branches, and occasionally on rocks, in humid broadleaved and mixed evergreen forest, across a wide altitudinal span. The three Bhutan gatherings cited, from Trashigang at 1300 m and Chendebji at 2450 m flowering in April and May, and Tumching-La at 3000 m, illustrate its broad range from warm subtropical to cool temperate cloud forest where atmospheric moisture is high.

The species is a dwarf, much-branched epiphytic shrub with slender twigs clothed in scales and bearing small, obovate, leathery leaves whose lower surface is densely lepidote, resembling the foliage of Vaccinium as the epithet implies. The flowers are small, solitary or few together at the branch tips, with a short tubular to campanulate, white to pale pink corolla, the lobes spreading; the ovary and style are scaly. The fruit is a small lepidote capsule splitting septicidally to release numerous minute seeds adapted to wind dispersal in the canopy.

Rhododendron vaccinioides belongs to subgenus Rhododendron, section Vireya-allied scaly rhododendrons, an epiphytic lineage radiating through the wet forests of Asia. Its diminutive epiphytic habit is unusual among Himalayan rhododendrons. Widespread and locally frequent, it is of least conservation concern, though dependent on intact humid forest canopy.

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

Ericaceae

Rhododendron wallichii

by GP Jürgens

Hook. f.

Bhutan2014 988
Bhutan Chele-La 3900m, May
Bhutan2014 989
Bhutan Chele-La 3900m, May

Bh2008 575 P864 1
Bhutan Shele-La 3800m, May
Bh2008 573 P861 1
Bhutan Shele-La 3800m, May

Description

An evergreen rhododendron of the eastern Himalaya, native to China, Bhutan, Nepal and India, with about 353 GBIF occurrences (extra-range entries reflect cultivation in botanic gardens). It is a shrub to small tree of the upper subalpine and lower alpine zone, forming part of rhododendron-fir and dwarf rhododendron scrub, on cool, moist, humus-rich slopes generally between about 3300 and 4300 m. The depicted plants were photographed in May on the Bhutanese passes of Chele-La at around 3900 m and Shele-La at about 3800 m, exposed high-elevation habitats where it flowers as the snow recedes.

The species forms a rounded shrub with smooth, peeling bark and stout branchlets. The leaves are coriaceous, elliptic to oblong-elliptic, dark green and glabrous above, and beneath bear a distinctive thin, patchy, fawn to brownish indumentum of dendroid hairs that often wears away to leave scattered remnants. The flowers are borne in compact terminal trusses; each has a campanulate corolla of pale lilac to rose-pink, often with crimson basal blotches and spotting, the limb shallowly seven- to eight-lobed, with numerous stamens and a glabrous ovary topped by a slender style. The fruit is a curved, woody, septicidal capsule releasing many small winged seeds.

Though GBIF flags the name as a synonym, R. wallichii is widely accepted at species rank and placed in subsection Campanulata, allied to R. campanulatum, from which it is separated by its thinner, more fugacious leaf indumentum. Ecologically it is a major component of high Himalayan rhododendron heath, providing spring nectar and structural cover. Locally abundant within its range, it faces no immediate threat but is sensitive to grazing pressure, fire and the warming of its narrow alpine belt.

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

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

Commelinaceae

Rhopalephora scaberrima

by GP Jürgens

(Blume) Faden

Bhutan2015 254
Bhutan Zhemgang 910m, October

Description

Rhopalephora scaberrima is a tropical to subtropical spiderwort widely distributed across South and Southeast Asia, recorded from India, Nepal, Bhutan, Bangladesh, Sri Lanka, Myanmar, Thailand, Malaysia, Indonesia, the Philippines, Vietnam, southern China and Taiwan. Its GBIF profile, with about 1,104 occurrences spanning these countries, confirms a broad Indomalayan range. The plant illustrated was photographed in southern Bhutan at Zhemgang at about 910 m in October. It is a species of warm, humid lowland and lower-montane settings, growing in forest understorey, along shaded streambanks, in moist grassy clearings and on disturbed roadsides, generally below about 1,500 m where high rainfall and warmth prevail.

It is a perennial, somewhat straggling herb with ascending to decumbent stems that root at the lower nodes, the surfaces and leaf-sheaths conspicuously scabrid-hispid, as the epithet indicates. The leaves are alternate, ovate-lanceolate to elliptic, with a closed sheathing base and an acuminate apex. The flowers are borne in small scorpioid cymes aggregated into a terminal panicle; each has three free sepals and three blue to violet petals, with the androecium showing the differentiation characteristic of the family, the fertile stamens separated from reduced staminodes. The fruit is a small loculicidal capsule, distinctively two-locular with the seeds arranged in two rows, a key feature separating Rhopalephora from related genera.

The genus Rhopalephora was segregated from the broadly defined Aneilema and Commelina on the basis of its bilocular capsule, biseriate seeds and stamen architecture, as clarified in Faden's revisionary work. As a common and adaptable plant of disturbed humid habitats, R. scaberrima is not threatened and serves as a useful indicator of warm, moist forest edge in the eastern Himalayan foothills.

Author: (Blume) Faden · Sources: POWO (Kew), Flora of China Vol. 24, Flora of Bhutan Vol. 3, GBIF, Faden: Commelinaceae (revisionary studies)

Anacardiaceae

Rhus chinensis

by G & P Jürgens

Mill.

Bhutan2012 535
Bhutan Wangdi 2600m, September
Bhutan2015 252
Bhutan Zhemgang 900m, October

Description

Rhus chinensis is a widespread deciduous shrub or small tree of East and South Asia, recorded across China, Taiwan, Japan, Korea, India, Vietnam, Thailand, Myanmar, Nepal, Bhutan and beyond, with more than ten thousand documented occurrences making it one of the most frequently collected sumacs in the region. It is a pioneer of open and disturbed ground, colonising forest margins, clearings, roadsides, scrub and abandoned cultivation from the lowlands into the montane zone. In Bhutan it ranges over a wide elevational band, as shown by collections near Wangdi at about 2600 m in September and at Zhemgang at 900 m in October, the autumn dates corresponding to fruiting.

The plant is a shrub to small tree with greyish bark and stout, often warted branchlets. The leaves are alternate and odd-pinnate, the rachis characteristically winged between the leaflets; the leaflets are ovate to oblong, coarsely serrate, acuminate, and tomentose beneath, turning red in autumn. The inflorescence is a large terminal pubescent panicle of numerous small whitish to greenish-yellow flowers, the plant functionally dioecious. The fruit is a small, flattened, reddish drupe covered with short hairs and a sour, salty surface bloom.

Rhus chinensis is the principal host of the Chinese sumac aphid Schlechtendalia chinensis, whose feeding induces large hollow leaf galls extraordinarily rich in tannins; these galls, known as Chinese galls or wubeizi, are harvested as a major commercial source of gallotannic acid and are valued in traditional medicine and dyeing. Wax from the fruit and the tannin-laden tissues have long been utilised economically. Hardy, fast-growing and broadly tolerant of disturbance, the species is abundant throughout its range and faces no conservation concern, functioning ecologically as an early-successional colonist.

Author: Mill. · Sources: POWO (Kew), GBIF, Flora of China Vol. 11, Flora of Bhutan Vol. 2, Flora of Nepal, Flora of Pakistan, Min & Barfod treatment of Anacardiaceae