Author

GP Jürgens

Ericaceae

Rhododendron anthopogon

by GP Jürgens

D. Don

Sikkim2011 95
Sikkim Chopra-valley 4200m, June
Sikkim2011 96
Sikkim Chopra-valley 4200m, June

Description

Rhododendron anthopogon is a dwarf, aromatic alpine shrub of the Himalaya, recorded in GBIF (around 1052 occurrences) from Nepal, India, China, Bhutan and Pakistan. It dominates open alpine slopes, moorland, rocky ridges and the upper limit of shrub vegetation, generally between 3000 and 5000 m, often forming extensive low thickets above the tree line together with junipers and other dwarf rhododendrons. The photographed population in the Chopra valley of Sikkim at 4200 m in June represents this typical high-alpine, exposed habitat, where it flowers as snow recedes in early summer.

It is a low, much-branched, evergreen shrub usually under 1 m tall, with young shoots bearing peltate scales. The small, alternate, leathery leaves are elliptic to ovate, aromatic when crushed, densely brown-scaly (lepidote) beneath and with a slightly recurved margin. The flowers are borne in compact terminal clusters; each has a narrowly tubular corolla, white to pale pink or cream, with a short spreading limb of five lobes and a hairy throat, and characteristically only five to ten included stamens. The fruit is a small, scaly, dehiscent capsule releasing minute seeds.

Rhododendron anthopogon is the type of subsection Pogonanthum within section Rhododendron (the lepidote rhododendrons), a group of aromatic, scaly, tubular-flowered dwarf alpines centred on the Himalaya and western China. Its foliage is rich in essential oils and is harvested as the incense and herbal medicine sunpati. Widespread and often locally abundant across the high Himalaya, it is assessed as Least Concern, functioning as a key soil-stabilising and structural component of alpine heath ecosystems.

Author: D. Don · Sources: POWO (Kew), GBIF, Flora of Bhutan, The Rhododendrons of Sikkim-Himalaya, Annotated Checklist of the Flowering Plants of Nepal, Cullen revision of lepidote Rhododendron

Ericaceae

Rhododendron anthopogon subsp. hypenanthum

by GP Jürgens

(Balf. f.) Cullen

Nepal 99 146 ergebnis
West-Nepal South of Rara-Lake 3700m, June
Garh 07 441 ergebnis
Garh 07 379 ergebnis
India Garhwal Khiar Kutti 4000m, June

Description

Rhododendron anthopogon subsp. hypenanthum is a dwarf alpine shrub of the high Himalaya and adjacent Tibetan ranges, recorded from China, India, Pakistan, Nepal and Bhutan. It is a characteristic component of the dwarf-rhododendron heath that clothes open slopes, rocky moorland and the margins of alpine meadows above the treeline, frequently forming dense aromatic mats over granite and schist. The taxon ascends from roughly 3300 to over 4500 m; the photographed populations occur south of Rara Lake in West Nepal at about 3700 m and at Khiar Kutti in Indian Garhwal near 4000 m, both flowering in June as the snow retreats. With around 169 records it is a well-documented element of the subnival zone.

It forms a low, much-branched, intricate evergreen shrublet, the twigs densely scaly and the bark flaking. The small leaves are aromatic, elliptic to oblong, leathery, dark green and glabrous above, the lower surface densely covered by overlapping rusty-brown peltate scales, the margins often recurved. The flowers are borne in compact terminal capitate heads; the corolla is narrowly tubular with a short spreading limb of five lobes and is here a clear pale yellow, distinguishing this subspecies from the usually pink to cream typical race. Stamens are included within the tube. The fruit is a small scaly capsule splitting septicidally to release minute seeds.

Within section Pogonanthum, subsp. hypenanthum is separated from the more eastern subsp. anthopogon chiefly by its yellow corolla and western Himalayan distribution. The fragrant foliage is harvested locally for incense and traditional medicine. As a widespread, abundant alpine taxon it is of least conservation concern, though high-altitude grazing and a warming climate may shift the lower limits of its heathland communities.

Author: (Balf. f.) Cullen · Sources: POWO (Kew), GBIF, Flora of China, Flora of Bhutan, The Plant-Book (Cullen, Revision of Rhododendron section Pogonanthum)

Ericaceae

Rhododendron arboreum

by GP Jürgens

Sm.

Bh2008 31 G54
Bhutan
Nepal1992 220 P322 ergebnis
Nepal Nundhaki 1400m March 
Nepal1992 228 P337 ergebnis
Nepal Nundhaki 1400m March 
Nepal1992 237 P348 ergebnis
Nepal Nundhaki 1400m March 

Description

Rhododendron arboreum is the tree rhododendron of the Himalaya and the broader Indian subcontinent, ranging from Pakistan through India, Nepal, Bhutan and Myanmar into southwestern China, with a notable disjunct presence in the hills of Sri Lanka; widely cultivated, it appears in GBIF from many temperate countries and totals nearly 3000 occurrences. It is the most familiar species of the genus across its native range, growing in temperate broadleaved and oak-laurel forest, on hill slopes and in scrub, here recorded at Nundhaki in Nepal at 1400 m and in Bhutan. Spanning a broad elevational band, it flowers conspicuously in late winter and spring (March), painting Himalayan hillsides crimson.

It is an evergreen shrub or tree reaching 10-20 m, with a gnarled trunk and rough, flaking bark. The leaves are leathery, oblanceolate to elliptic, dark glossy green above and clothed beneath with a dense silvery, fawn or rusty indumentum that varies between subspecies. The flowers are massed in dense, rounded, terminal trusses of 15-20; each corolla is tubular-campanulate, 3-5 cm long, ranging from deep blood-red through pink to white, the throat marked with darker nectar spots. Stamens are typically 10, and the ovary tomentose with a long style. The fruit is a curved, woody, ribbed capsule splitting to release numerous small winged seeds.

Described by James Edward Smith, the species belongs to subgenus Hymenanthes, subsection Arborea, and is highly variable, with several recognised subspecies (e.g. subsp. cinnamomeum, subsp. nilagiricum, subsp. zeylanicum) differing in leaf indumentum and altitude. It is the national flower of Nepal (lali gurans) and the state tree of Uttarakhand, and the nectar-rich corollas are sought by sunbirds and bees, with the flowers used to make a local beverage. Although widespread and not globally threatened, lower-elevation populations face pressure from fuelwood harvesting, grazing and forest conversion.

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

by GP Jürgens

D.G.Long & S.Bowes-Lyon

BhutanPG2011 510
Bhutan Ludlow-Sherriff-Trail Warrtlang-La, 4500m June
BhutanPG2011 412
Bhutan Ludlow-Sherriff-Trail Warrtlang-La, 4500m June
BhutanPG2011 511
Bhutan Ludlow-Sherriff-Trail Warrtlang-La, 4500m June

Description

Rhododendron bhutanense is a high-alpine shrub endemic to the eastern Himalaya, centred on Bhutan and adjacent India, with only about 59 GBIF records reflecting its restricted range. It is a component of the dwarf rhododendron heath and open alpine scrub that clothes exposed slopes near and above the treeline, typically between about 3500 and 4500 m. The photographed plant on the historic Ludlow–Sherriff trail at the Warrtlang La pass at 4500 m, flowering in June, exemplifies its occupancy of the highest shrub zone, where it endures intense irradiation, wind and frost on thin, acidic, peaty soils in the early summer flowering season.

The species is a low to medium evergreen shrub with stout branchlets. Its leaves are coriaceous, oblong to elliptic, with the lower surface bearing a dense indumentum (a felted tomentum) characteristic of the section to which it belongs, an adaptation reducing water loss and radiation damage at altitude. The flowers are borne in compact terminal trusses; the corolla is campanulate to funnel-campanulate, pink to pale rose or purplish, often with darker spotting within. Stamens are typically ten, and the ovary is densely hairy, maturing into a woody, septicidal capsule that releases numerous small seeds.

Rhododendron bhutanense was described by D.G.Long and S.Bowes-Lyon and is placed in subgenus Hymenanthes, allied to the indumented R. campanulatum group, its tomentose leaf undersides being a key diagnostic. As a narrow eastern-Himalayan endemic confined to a thin alpine band, it is of particular biogeographic and conservation interest: such high-altitude endemics are especially exposed to upslope habitat loss under climate warming, making monitoring of its limited Bhutanese populations worthwhile.

Author: D.G.Long & S.Bowes-Lyon · Sources: POWO (Kew), GBIF, Flora of Bhutan, Rhododendrons of Bhutan, Cullen & Chamberlain Revision of Rhododendron

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)