Tag:

Subalpine (2500-3500 m)

Ericaceae

Rhododendron aeruginosum

by GP Jürgens

Hook.f.

Sikkim2011 125
Sikkim Chopta-valley 4100m, June
Sikkim2011 349
Sikkim Lada-La 4000m, June
Sikkim2011 362
Sikkim Lada-La 4000m, June
Sikkim2003 422 P587 2
Sikkim Chopta Valley 3400m August

Description

Rhododendron aeruginosum is an evergreen shrub of the eastern Himalaya, native to Sikkim and the rest of India, Bhutan, Nepal and adjacent China. Its roughly 106 georeferenced records describe a narrowly distributed high-montane taxon. It grows in the upper subalpine to lower alpine belt, forming dense thickets on open slopes, ridges and rocky pasture above the treeline at roughly 3300-4400 m. The Sikkim collections noted above, from the Chopta valley at 3400-4100 m and Lada-La at 4000 m in June and August, are characteristic of its windswept, high-elevation habitat at and above the krummholz zone.

It is a compact shrub whose striking young leaves are covered with a thick, glaucous blue-green to verdigris waxy bloom, the epithet aeruginosum meaning "rust- or copper-coloured." The mature leaves are elliptic to oblong, leathery and coated beneath with a dense fawn to rufous indumentum. The flowers are borne in compact terminal trusses and are broadly campanulate, pale rose to white often flushed pink and spotted within, with ten stamens and a glabrous ovary. The fruit is a curved, woody, septicidal capsule releasing many small seeds.

Rhododendron aeruginosum is closely allied to R. campanulatum, under which name it has often been treated as a high-altitude variant or subspecies and to which the original web placement refers, the two distinguished chiefly by the glaucous juvenile foliage and dwarfer, more exposed habit of aeruginosum. It belongs to the large elepidote subgenus Hymenanthes and subsection Campanulata. Pollination is by bumblebees and other alpine insects. Its restricted high-altitude range makes it locally vulnerable to grazing, fire and the upslope compression of alpine shrubland under a warming climate.

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

Ericaceae

Rhododendron arboreum subst. cinnamomeum

by GP Jürgens

(Wall. ex G. Don) Tagg.

Bhutan2014 370
Bhutan Jakar 3900m, May
Nepal 97 225 G465
Nepal Thudam 3850m April
Nepal 1994 286 ergebnis
Ost-Nepal Milka-Danda 3100m May 

Description

Rhododendron arboreum var. cinnamomeum (Wall. ex G. Don) Tagg is a high-elevation race of the widespread tree rhododendron distributed across the eastern and central Himalaya, with records concentrated in Nepal, Bhutan, Sikkim and adjacent China. It occupies the upper temperate to subalpine belt, typically between 3000 and 3900 m, forming dense thickets and the canopy of mossy fir-rhododendron forest. The photographed populations span this range, from Bhutan's Jakar valley at 3900 m and Nepal's remote Thudam at 3850 m to the Milka-Danda ridge of eastern Nepal at 3100 m, all flowering between April and May as the snow retreats. It thrives on acidic, humus-rich soils on cool, north-facing slopes with high atmospheric humidity.

This variety is a shrub or small gnarled tree distinguished from typical R. arboreum by the dense, persistent indumentum on the lower leaf surface. The leathery, oblong-lanceolate to oblanceolate leaves are dark green and rugose above, while beneath they bear a thick, felted, cinnamon- to rust-brown tomentum (the source of the epithet cinnamomeum). Flowers are borne in compact, rounded terminal trusses; the campanulate corolla, ranging from deep blood-red through pink to occasional white, has dark nectar pouches and conspicuous spotting on the upper lobes. The fruit is a woody, curved, dehiscent capsule releasing numerous minute winged seeds.

Taxonomically the taxon sits within the polymorphic R. arboreum complex (subgenus Hymenanthes), where the white-flowered, heavily indumented high-altitude plants have at times been treated as a distinct subspecies. The species is the national flower of Nepal and a foundational element of Himalayan cloud-forest ecosystems, supporting sunbirds and other nectarivores as pollinators. While not globally threatened, upper-montane var. cinnamomeum populations are sensitive to grazing, fuelwood collection and climate-driven treeline shifts.

Author: (Wall. ex G. Don) Tagg. · Sources: POWO (Kew), GBIF, Flora of Bhutan, Flora of China, The Genus Rhododendron (Cox & Cox), Rhododendrons of the Himalaya (Tagg)

Ericaceae

Rhododendron argipeplum

by GP Jürgens

Balf. f. & R.E. Cooper

Bhutan2014 445
Bhutan Yatong-La 3200m, May

Description

Rhododendron argipeplum Balf.f. & R.E.Cooper is an eastern Himalayan species of restricted distribution; GBIF records (about 77 occurrences) come from Bhutan, neighbouring northeastern India and adjacent China. It is a shrub or small tree of the cool-temperate forest belt, growing in mixed broad-leaved and conifer forest, rhododendron thickets and along ridges and ravines, generally between about 2700 and 3600 m. The individual photographed at Yatong-La in Bhutan at 3200 m in May, flowering as the higher passes thaw, is typical of its montane setting in the humid, cloud-influenced forests of the eastern range, where deep leaf litter and high atmospheric moisture prevail.

It forms a much-branched shrub up to several metres tall, the young shoots and petioles bristly-setose. The leaves are leathery and elliptic to oblong-ovate, dark green and glabrescent above, and clothed beneath with a thin, often bicoloured indumentum overlying a fawn-coloured felt. The flowers are borne in compact terminal trusses; the corolla is tubular-campanulate, fleshy, and deep red to crimson, usually with darker nectar pouches at the base. There are typically ten stamens, and the ovary bears a glabrous to setose style. The fruit is a woody, curved septicidal capsule splitting to release numerous small winged seeds.

The species belongs to subgenus Hymenanthes, subsection Barbata, a group of red-flowered, setose-stemmed Himalayan rhododendrons in which species delimitation has been debated; it has at times been confused with Rhododendron smithii and allies. Pollination of the showy red corollas is associated with birds and large bees. Owing to its limited eastern Himalayan range and dependence on intact temperate forest, the species is regionally restricted, and like many Bhutanese rhododendrons it is potentially vulnerable to forest clearance and to the pressures of climate change on the narrow montane belt it occupies.

Author: Balf. f. & R.E. Cooper · Sources: POWO (Kew), GBIF, Flora of Bhutan, The Rhododendrons of Bhutan, Flora of China, Royal Botanic Garden Edinburgh revision of subgenus Hymenanthes

Ericaceae

Rhododendron baileyi

by GP Jürgens

Balf. f.

Sikkim2011 204
Sikkim Lachung 3100m, June
Sikkim2011 205
Sikkim Lachung 3100m, June
Sikkim2004 435 P758
Sikkim/India Lachung 3600m May

Description

Rhododendron baileyi is a lepidote shrub of the eastern Himalaya, native to Sikkim and the rest of northern India, Bhutan and south-eastern Tibet in China, with the remaining GBIF records (Great Britain, Canada, Japan, Sweden, United States) reflecting its presence in cultivation. Its roughly 121 georeferenced records indicate a narrowly distributed but well-known garden plant. It grows in open subalpine forest, rocky slopes and rhododendron-dominated thickets at roughly 3000-4300 m. The Sikkim collections noted above, from the Lachung valley at 3100-3600 m in May and June, are characteristic of its montane habitat.

It is a small to medium evergreen shrub with scaly young shoots, the leaves elliptic to oblong, leathery and densely covered beneath with overlapping reddish-brown lepidote scales that give the undersurface a rusty, almost continuous coating. The flowers are borne in compact terminal clusters and are widely campanulate to saucer-shaped, deep reddish-purple to magenta, often darker-spotted within, with the corolla and the exserted stamens and style bearing scattered scales. The fruit is a small ovoid, scaly, septicidal capsule splitting to release numerous minute seeds.

Within the genus Rhododendron, R. baileyi belongs to the lepidote subgenus and is placed in subsection Baileya, a small group distinguished by its strongly flattened, overlapping leaf scales and richly coloured flat-faced flowers. Named for the explorer F. M. Bailey, it has been valued in horticulture since its introduction. Pollination is by bumblebees and other long-tongued insects of the high Himalaya. Although not broadly assessed, its limited natural range and dependence on intact subalpine shrubland make it locally sensitive to grazing, fire and forest disturbance.

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

Ericaceae

Rhododendron barbatum

by GP Jürgens

Wall. ex G. Don

Bhutan2014 592
Bhutan Gogona 2950m, May
Nepal 97 133 P245
Nepal Mewa-Khola 2800m April
Nepal1992 139 P199 ergebnis
Nepal Milka Danda 2800m March 
Nepal1992 47 P68 ergebnis
Nepal Milka Danda 2800m March 
Nepal1992 49 P73 ergebnis
Nepal Milka Danda 2800m March 

Description

Rhododendron barbatum is a tree-forming rhododendron of the central and eastern Himalaya, distributed through Nepal, India, China and Bhutan, with about 509 occurrence records (those reported from Britain, North America and Korea reflecting its long history in cultivation). It forms a major component of temperate broadleaf and conifer forests, often dominating moist, north-facing slopes and ridge crests, generally between about 2400 and 3700 m. The photographed plants—Gogona in Bhutan at 2950 m in May, and Mewa-Khola and Milka Danda in eastern Nepal at 2800 m in March and April—illustrate its early-spring flowering in these mid-montane forests.

It is an evergreen shrub or small tree with smooth, peeling, reddish-brown to purplish bark, a striking feature of mature trunks. Young shoots and petioles bear conspicuous stiff bristles, the "barbate" character giving the species its name. The leaves are leathery, oblong-elliptic to obovate, glabrous and dark green above and pale beneath. The flowers are borne in dense, rounded terminal trusses; the corolla is tubular-campanulate and a vivid blood-red, with darker nectar pouches at the base, and the calyx is enlarged and coloured. The fruit is a woody, curved, several-valved capsule releasing many minute seeds.

Rhododendron barbatum, described from Wallich's material by G. Don, belongs to subgenus Hymenanthes, the large-leaved "true" rhododendrons, and hybridises in cultivation with allied red-flowered species. Its early bloom is an important nectar source for high-altitude birds and insects. Although widespread and locally abundant, Himalayan forest rhododendrons face pressure from fuelwood cutting, grazing and a warming climate altering the temperate forest belt.

Author: Wall. ex G. Don · Sources: POWO (Kew), GBIF, Flora of China (Ericaceae), Annotated Checklist of the Flowering Plants of Nepal, Grierson & Long Flora of Bhutan, Royal Botanic Garden Edinburgh's Revision of the Genus Rhododendron

Ericaceae

Rhododendron camelliiflorum

by G & P Jürgens

Hook.f.

BhutanPG2011 31
Bhutan Pele-La, 2800m June
BhutanPG2011 693 1
Bhutan Luksor, 2900m July

Description

Rhododendron camelliiflorum is a Himalayan endemic shrub restricted to the moist temperate belt of Nepal, India, Bhutan and adjacent China (Xizang), with 165 GBIF occurrences. It is characteristically epiphytic or lithophytic, growing on mossy tree trunks, rocks and banks within humid Abies, Tsuga and broadleaved forest, typically between about 2500 and 3500 m. The photographs were taken in Bhutan at Pele-La at 2800 m in June and at Luksor at 2900 m in July, cool cloud-forest sites where persistent mist and abundant epiphytic moss create the damp microhabitats this species favours.

It is a small, straggling evergreen shrub with scaly young shoots and coriaceous, elliptic to oblanceolate leaves that are dark green and lepidote (densely scaly) beneath, with revolute margins and an acute, mucronate apex. The flowers are borne singly or in small terminal clusters and are notably fleshy; the campanulate to broadly tubular, five-lobed corolla is waxy white, often flushed with pink or rose, recalling a small camellia, whence the epithet. The stamens are typically ten, with the ovary and style densely scaly. The fruit is a dry, scaly, septicidal capsule releasing numerous minute seeds.

The species belongs to subgenus Rhododendron, section Rhododendron (the lepidote rhododendrons), and its thick-textured flowers and epiphytic tendency distinguish it within the Himalayan assemblage. Its summer flowering and inaccessible epiphytic habit have kept it scarce in cultivation. Though confined to a narrow elevational band, it remains locally frequent in intact forest and is not currently considered globally threatened, but it is vulnerable to forest degradation across the eastern Himalaya.

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

Ericaceae

Rhododendron campanulatum

by GP Jürgens

D. Don

Sikkim2004 128 P223
Sikkim/India Singalila 2600m April
Nepal 97 229 P476
Nepal Thudam 3800m April
Nepal 97 239 W494
Nepal Thudam 3800m April
Nepal 2001 328 ergebnis ergebnis scaled
Nepal 2001 351 ergebnis ergebnis scaled
Nepal 2001 327 ergebnis ergebnis scaled
Nepal (Gorkha) Rupina-La 3250m, May

Description

Rhododendron campanulatum D. Don is an evergreen Himalayan shrub or small tree distributed through Nepal (NP), India (IN), Bhutan (BT) and southern China (CN), with GBIF logging 1357 occurrences plus numerous cultivated records from Britain, North America and Europe. It forms dense thickets at and above the temperate treeline, in subalpine fir and birch forest and on open alpine slopes. The image documents populations across its range: Singalila on the Sikkim-India ridge at 2600 m in April, Thudam in Nepal at 3800 m in April, and the Rupina-La in Gorkha at 3250 m in May, reflecting the species' role as a dominant of the upper forest belt.

The plant is a much-branched shrub with stout twigs and a characteristically thick, rufous indumentum of dendroid hairs on the lower leaf surface. The leaves are coriaceous, elliptic to oblong, dark green and glabrous above, the undersurface densely felted with cinnamon-brown to fawn tomentum. The flowers are borne in compact terminal trusses; each has a broadly campanulate corolla, pale lilac to rose-purple or whitish, often spotted within, with five lobes and ten stamens. The fruit is a curved, woody, septicidal capsule releasing numerous small winged seeds.

Rhododendron campanulatum belongs to subgenus Hymenanthes, the large-leaved tomentose-leaved alliance, and includes subsp. aeruginosum with strikingly glaucous young foliage. As a treeline dominant it strongly influences alpine ecology, and recent studies have documented its upslope migration and densification in response to warming, with implications for fragile alpine meadows. It is widely cultivated and has contributed to garden hybrids. The species remains common and is not considered threatened.

Author: D. Don · Sources: POWO (Kew), GBIF, Flora of Nepal, Flora of Bhutan, Rhododendron monograph (Davidian; Royal Botanic Garden Edinburgh revision)

Ericaceae

Rhododendron campylocarpum

by GP Jürgens

Hook. f.

Bh2008 237 P374
Bhutan Tumching-La, 3600m April
Bh09 83 G141
Bhutan Langchlakha, 3700m June
Sikkim2004 403 G687
Sikkim/India Lachung 3300m May
Sikkim 2006 372 ergebnis
India West-Bengal, Tamrong 2850m, May

Description

Rhododendron campylocarpum is an East Himalayan species distributed through the higher ranges of Nepal, Sikkim and Darjeeling in India, Bhutan, southern Tibet (China) and northern Myanmar, with abundant horticultural records (GB, US, NZ, etc.) reflecting long cultivation in temperate gardens; GBIF holds some 676 occurrences. It grows in the upper temperate and subalpine zone, typically between about 2850 and 3700 m, as documented at Tumching-La (3600 m) and Langchlakha (3700 m) in Bhutan, at Lachung (3300 m) in Sikkim and at Tamrong (2850 m) in West Bengal, inhabiting conifer and Abies forest margins, rhododendron thickets and moist rocky slopes near the treeline. It flowers in late spring and early summer (April-June).

It is an evergreen, much-branched shrub or small tree reaching 1-4 m, with smooth, peeling bark. The leaves are alternate, clustered toward the branch tips, broadly ovate to elliptic-oblong, 4-10 cm long, rounded to cordate at the base, glabrous and dark green above and conspicuously glaucous beneath. The inflorescence is a lax, terminal truss of 5-12 flowers; the corolla is campanulate, 3-4 cm across, clear sulphur- to canary-yellow, frequently with a crimson basal blotch within. Stamens are 10, included; the ovary and slender style are usually glandular. The fruit is a curved, cylindrical capsule, the epithet ("campylocarpum", bent fruit) referring to this curvature.

The species belongs to subgenus Hymenanthes, subsection Campylocarpa, a small group of yellow-flowered Himalayan rhododendrons including R. wardii and R. callimorphum, and it hybridises freely in the wild and in cultivation. Introduced by J. D. Hooker in the 1850s, it became an important parent of many garden hybrids and is an early-summer nectar source for bumblebees and other high-altitude pollinators. Though locally common and not globally threatened, individual populations are subject to grazing, fuelwood collection and the upward shift of the treeline.

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

Ericaceae

Rhododendron campylocarpum x Rhododendron thomsonii

by GP Jürgens
Sikkim2004 404 P689
Sikkim/India Lachung 3400m May

Description

This plant is a natural hybrid between Rhododendron campylocarpum and Rhododendron thomsonii, both subalpine to alpine shrubs of the Eastern Himalaya whose ranges overlap broadly in Sikkim, Bhutan, eastern Nepal and southern Tibet. Because it is a hybrid rather than a described species, it carries no meaningful GBIF distribution of its own — the apparent global record set and the placeholder accepted name 'Plantae' reflect database artefacts, not a real occurrence pattern. Such intermediates arise wherever the two parents grow intermingled in mossy fir and Rhododendron forest and on open subalpine slopes. The photographed plant from Lachung in northern Sikkim, near 3400 m and flowering in May, lies squarely within the elevational overlap zone of about 3000-4000 m where natural hybridisation is frequent.

Morphologically the hybrid is intermediate between its parents. From R. thomsonii it tends to inherit smooth, often peeling, reddish bark, rounded to obovate-orbicular leaves glaucous beneath, and a calyx that is enlarged and cupular; from R. campylocarpum it derives a more campanulate corolla and a tendency toward yellow pigmentation. The resulting flowers are typically campanulate and pale yellow to creamy, frequently flushed or blotched pink to rose, borne in loose terminal trusses; the curved capsule shows the influence of campylocarpum (the 'curved-fruited' parent). Stamens number ten and the style is glabrous.

Both parents belong to Rhododendron subgenus Hymenanthes (the elepidote rhododendrons), and their hybrid swarms are a classic example of natural introgression, long noted in Sikkim by J. D. Hooker. These intermediates blur species limits in the field and are of horticultural importance, both parents being foundational in the breeding of yellow- and red-flowered garden hybrids.

Sources: POWO (Kew), GBIF, Flora of Bhutan, The Rhododendron Handbook (Royal Horticultural Society), Cox & Cox A Encyclopedia of Rhododendron Species, Hooker The Rhododendrons of Sikkim-Himalaya

Ericaceae

Rhododendron ciliatum

by GP Jürgens

Hook. f.

Bhutan2014 551
Bhutan Phobjika 2810, May
Bhutan2014 553
Bhutan Phobjika 2810, May
Bh2008 404 P634
Bhutan Phobjika, 3100m April
Bh2008 404 P634 scaled
Bhutan Phobjika, 3100m April
Nepal 1994 70 ergebnis
Ost-Nepal Jaljale Himal, 2800m April

Description

Rhododendron ciliatum is a low evergreen shrub of the Eastern Himalaya, with verified native occurrences in India, Nepal, Bhutan and China; numerous further GBIF records from Britain, North America, Austria, Italy, New Zealand and elsewhere reflect its wide cultivation. It grows on open hillsides, rocky slopes and forest margins, often epiphytically on mossy trunks, in the upper-temperate and subalpine zones between about 2700 and 3700 m. The cited material from Phobjika in Bhutan (2810-3100 m, April-May) and the Jaljale Himal of eastern Nepal (2800 m, April) shows the species in its characteristic early-spring flowering.

It forms a compact, rounded shrub usually under 1.5 m with peeling reddish-brown bark and bristly young shoots. The elliptic to oblong leaves are leathery and dark green, conspicuously fringed at the margins and on the midrib beneath with long stiff cilia, the feature giving the species its name, and scaly below. The flowers are borne in small terminal trusses of two to five; the corolla is broadly funnel-campanulate, white to pale pink, often deeper rose in bud, with a slightly nodding posture. The fruit is a small ovoid scaly capsule that splits to release abundant minute winged seeds.

Rhododendron ciliatum belongs to subgenus Rhododendron, subsection Maddenia, a lepidote (scaly) group, and was described by J.D. Hooker from his Sikkim collections; it has contributed extensively to horticultural hybridisation for its hardiness and early bloom. Ecologically it is an early-spring nectar source in the high forest. Widespread and locally common across its native range and abundant in cultivation, it is not regarded as threatened.

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