Author

GP Jürgens

Polygonaceae

Rheum nobile

by GP Jürgens

Hook. f. & Thomson

Sikkim2011 328
Sikkim Lada-La 4400m, June
Sikkim2003 309 G438
Sikkim Saniti-Lake 4300m August
Sikkim2003 310 W439
Sikkim Saniti-Lake 4300m August

Description

Rheum nobile, the Sikkim or noble rhubarb, is a spectacular high-alpine perennial of the eastern Himalaya, distributed from Nepal through Sikkim and northern India into Bhutan, Myanmar and south-western China, with around 220 occurrence records. It is a strict specialist of open alpine screes, moraines and rocky slopes, typically between about 4000 and 4800 m. The images derive from Sikkim at Lada-La (4400 m, June) and near Saniti Lake (4300 m, August), localities characteristic of the high, exposed scree habitat in which this iconic "glasshouse plant" grows.

The species forms a stout, columnar flowering spike to about 1-2 m, arising from a thick taproot. Its most striking feature is the dense, overlapping series of large, translucent, straw-coloured to pale yellow bracts that sheathe the entire inflorescence, hiding the small flowers within. The basal leaves are large, broadly ovate to orbicular and reddish-margined, forming a rosette. The numerous small flowers are greenish and inconspicuous, concealed beneath the bracts, and develop into small, three-winged nutlets (achenes) typical of the genus.

Rheum nobile (Polygonaceae) is a classic example of a Himalayan "greenhouse" or glasshouse plant: the translucent bracts trap solar heat and create a warm, sheltered microclimate that protects the developing flowers from cold, wind and intense ultraviolet radiation while attracting and harbouring specialist pollinating midges. This remarkable adaptation, much studied in plant ecophysiology, makes the species a celebrated model of high-altitude floral biology. Though localised, it is of least conservation concern, but its restriction to a narrow alpine belt makes it potentially vulnerable to climatic warming.

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

Crassulaceae

Rhodiola chrysanthemifolia

by GP Jürgens

(H. Lév.) Fu

Sikkim2003 396 G557
Sikkim Zemu Valley 3450m August
Sikkim2003 397 P558
Sikkim Zemu Valley 3450m August

Description

Rhodiola chrysanthemifolia is a high-altitude succulent of the Himalaya and adjacent China, recorded from China, Nepal, India and Bhutan with more than 630 georeferenced occurrences. It is a plant of alpine meadows, rocky slopes, cliff crevices and stabilised screes, typically growing well above the treeline. The population photographed in the Zemu Valley of northern Sikkim at about 3450 m in August represents its characteristic alpine habitat, flowering and fruiting in late summer on cool, well-drained, often rocky substrates exposed to intense montane conditions.

The species is a glabrous perennial arising from a stout, woody, often branched caudex topped by a persistent rootstock. The annual flowering stems bear numerous alternate, fleshy leaves that are toothed to pinnately incised, the dissection recalling the foliage of Chrysanthemum and reflected in the epithet chrysanthemifolia. The flowers are grouped in dense terminal cymes; as in Rhodiola the plant is typically dioecious, with the small four- to five-merous flowers bearing distinct sepals and yellow to greenish-yellow or reddish-tinged petals. The fruit comprises erect, beaked follicles that split along the inner suture to release the small seeds.

Rhodiola, segregated from Sedum on the basis of its perennial caudex, dioecy and basally connate carpels, is a circumboreal and alpine Asian genus of considerable interest for its adaptogenic secondary chemistry. Several Himalayan congeners are intensively harvested for medicinal roots, placing wild populations under pressure, although R. chrysanthemifolia itself remains widespread and locally common across the high Himalaya and is not presently regarded as threatened.

Author: (H. Lév.) Fu · Sources: POWO (Kew), GBIF, Flora of Nepal, Flora of China, Flora of Bhutan, Ohba's studies of Himalayan Crassulaceae

Crassulaceae

Rhodiola crenulata

by GP Jürgens

(Hook.f. & Thomson) H.Ohba

BhutanPG2011 537 ergebnis
Bhutan, Tem-Tso 4640m, June
BhutanPG2011 538 ergebnis
Bhutan, Tem-Tso 4640m, June
Bhutan Ludlow-Sherriff-Trail Dem-Tso, 4650m June

Description

Rhodiola crenulata (Hook.f. & Thomson) H.Ohba is a succulent perennial of the high Himalaya and Tibetan plateau, distributed across China, Nepal, India, Bhutan and Pakistan. It is recorded from Bhutan at Tem-Tso and along the Ludlow-Sherriff trail near Dem-Tso between 4640 and 4650 m, flowering in June, exemplifying its strict confinement to the upper alpine zone. The species colonises rocky alpine meadows, scree, cliff ledges, moraine and well-drained gravelly slopes, generally between 4000 and 5600 m, where it withstands extreme cold, desiccating winds and high ultraviolet flux. Its roughly 484 GBIF records confirm a genuine but specialised high-elevation presence.

The plant arises from a stout, branched, woody caudex and thick fleshy rootstock that is reddish or yellowish within and aromatic. Numerous short, erect flowering stems bear crowded, sessile, glaucous leaves that are oblong to obovate and crenulate to dentate at the apex, giving the epithet. The species is usually dioecious, the flowers grouped in dense terminal corymbose cymes; they are small and typically four- to five-merous, with petals ranging from deep red and pink to greenish-white, the staminate flowers showing exserted stamens. The fruit is a cluster of erect, several-seeded follicles that turn red at maturity.

Rhodiola crenulata belongs to the genus Rhodiola, segregated from Sedum and centred on the cold deserts and alpine zones of Asia. The thick rhizome, rich in salidroside, rosavin and related compounds, makes it the principal source of "hong jing tian" in Tibetan and Chinese medicine, and intensive wild harvesting for the adaptogen trade has driven serious population decline across parts of its range. Slow growth at extreme altitude renders it especially vulnerable, prompting growing interest in cultivation and sustainable management.

Author: (Hook.f. & Thomson) H.Ohba · Sources: POWO (Kew), GBIF, Flora of China, Flora of Bhutan, Sedum and Rhodiola of the Himalaya (Ohba), Crassulaceae monograph (Ohba)

Crassulaceae

Rhodiola cretinii

by GP Jürgens

(Raym.-Hamet) H. Ohba

BhutanPG2011 280
Bhutan Jule-Tso, 4100m June
BhutanPG2011 520
Bhutan Jule-Tso, 4100m June

Description

Rhodiola cretinii is a high-alpine succulent perennial of the Himalaya and adjacent Tibetan region, recorded from China, Nepal, India and Bhutan, with around 140 occurrences in GBIF. It is a plant of the upper alpine zone, growing on rocky slopes, screes, cliff ledges, moraines and stony turf, typically well above the treeline between about 3800 and 5000 m. The photographed material was collected in Bhutan at Jule-Tso at 4100 m in June, an elevation and rocky alpine setting fully consistent with the genus's affinity for cold, exposed, free-draining high-mountain ground.

The plant arises from a stout, fleshy, often woody caudex or rootstock crowned with the persistent remains of old leaf-bases. The flowering stems are short and erect, densely clothed with small, fleshy, alternate, sessile leaves that are flat to terete and entire or finely toothed at the apex. The flowers are crowded into a compact terminal cyme; like many alpine Rhodiola the species tends to be dioecious or functionally unisexual, the small flowers with greenish-yellow to reddish, often four- to five-merous perianths. The fruit is a cluster of erect to spreading follicles, each splitting to release numerous minute seeds.

Rhodiola, segregated from Sedum, comprises crassulacean stonecrops specialised for cold, arid and high-elevation habitats, employing succulence and a perennating caudex to survive harsh alpine winters. Several Himalayan species are harvested for traditional medicine, and although R. cretinii is not prominently exploited, slow-growing alpine perennials of this kind are inherently vulnerable to over-collection and habitat disturbance. Its compact cushion-like growth and dense leafy stems are typical adaptations to wind exposure, intense radiation and a short growing season.

Author: (Raym.-Hamet) H. Ohba · Sources: POWO (Kew), GBIF, Flora of China, Flora of Bhutan, Rhodiola monograph (Ohba)

Crassulaceae

Rhodiola fastigiata

by GP Jürgens

(Hook. f. & Thomson) S.H. Fu

Bh09 103 P181
Bhutan Jimilangtso, 4000m June
Garh 07 455 ergebnis
Garhwal Khiar-Kutti 3840m, June
Garh 07 538.7JPG ergebnis
Garhwal Khiar-Kutti 3840m, June

Description

Rhodiola fastigiata is a widespread high-alpine succulent of the Himalaya and the Sino-Himalayan ranges, well represented by some 724 georeferenced collections spanning China (CN), Nepal (NP), India (IN), Pakistan (PK), Bhutan (BT) and Myanmar (MM), with peripheral records from Mongolia (MN) and Afghanistan (AF). It is a plant of the upper subalpine and alpine zones, characteristically between roughly 3500 and 5000 m, colonising rocky slopes, screes, cliff ledges, moist alpine turf and the margins of snow-melt rills. The populations illustrated from Jimilangtso in Bhutan at about 4000 m and from Khiar-Kutti in Garhwal at 3840 m, both flowering in June, typify its occurrence in open, well-drained, high-elevation habitats.

It is a perennial herb arising from a stout, scaly, often branched caudex and thickened rootstock. Several erect, unbranched, fleshy flowering stems are produced, densely clothed throughout their length with crowded, overlapping, sessile leaves; these are narrowly oblong to linear-oblong, flat, entire or minutely toothed, somewhat glaucous and fleshy, giving the shoots a neat fastigiate aspect that gives the species its name. The inflorescence is a dense terminal corymb of small flowers, usually functionally dioecious, with five reddish to purplish-red sepals and petals; the staminate flowers bear ten stamens. The fruit is a cluster of erect, reddish, several-seeded follicles.

Rhodiola (Crassulaceae), formerly merged with Sedum, comprises stress-tolerant CAM succulents adapted to cold, arid, high-radiation alpine environments, where the swollen rootstock stores water and carbohydrate. Several Himalayan species, including this one, are harvested for traditional medicine for their adaptogenic rhizomes, creating localised collection pressure. R. fastigiata is broadly distributed and not currently considered threatened, but high-altitude Rhodiola populations are slow-growing and vulnerable to overharvesting.

Author: (Hook. f. & Thomson) S.H. Fu · Sources: POWO (Kew), GBIF, Flora of China, Flora of Bhutan, Flora of Pakistan, Ohba monographic studies of Himalayan Crassulaceae (Rhodiola)

Crassulaceae

Rhodiola himalensis

by GP Jürgens

(D. Don) Fu

Garw 2005 349 ergebnis
Garhwal Pataathi 4150 m, September
Bh09 132 P231
Bhutan Jimilangtso 4050m, June
Sikkim2011 292
Sikkim Lada-La 4000m, June

Description

Rhodiola himalensis is a characteristic high-alpine succulent of the Himalaya and adjacent Sino-Himalayan mountains, documented by some 562 georeferenced records from Nepal (NP), China (CN), India (IN), Bhutan (BT), Pakistan (PK) and Mongolia (MN), with a peripheral record in Japan (JP). It occupies the alpine zone, broadly between 3500 and 5000 m, on rocky slopes, screes, grassy alpine meadows, stream banks and moist ledges. The collections cited from Pataathi in Garhwal at 4150 m, Jimilangtso in Bhutan at about 4050 m and Lada-La in Sikkim at 4000 m, flowering between June and September, illustrate its broad occurrence across the central and eastern Himalaya at consistently high elevation.

It is a perennial herb arising from a stout, scaly, branched caudex topped by a fleshy rootstock. The flowering stems are erect to ascending and clothed with numerous, spreading, flat, sessile leaves; these are oblong-lanceolate to elliptic, fleshy, entire to minutely toothed, and often somewhat glaucous. The species is dioecious, the small flowers gathered into a dense terminal corymb; the staminate flowers are dark red to purplish with four parts and eight stamens, while the pistillate flowers develop into clusters of erect, dark red to purplish follicles bearing numerous minute seeds. The dark, often blackish-purple inflorescence colour is a notable field character.

Rhodiola (Crassulaceae), segregated from Sedum, comprises cold-adapted, perennating CAM succulents whose persistent woody caudex enables survival of harsh alpine winters and short growing seasons. R. himalensis, like several congeners, is gathered for use in Tibetan and Himalayan traditional medicine, contributing to localised harvesting pressure. The species remains widespread and is not formally threatened, though slow regeneration makes high-altitude Rhodiola populations vulnerable to sustained overcollection.

Author: (D. Don) Fu · Sources: POWO (Kew), GBIF, Flora of China, Flora of Bhutan, Annotated Checklist of the Flowering Plants of Nepal, Ohba monographic studies of Himalayan Crassulaceae (Rhodiola)

Crassulaceae

Rhodiola humilis

by GP Jürgens

(Hook. f. & Thomson) Fu

Bhutan2012 88
Bhutan Shele-La, 4100m September

Description

Rhodiola humilis is a dwarf high-alpine stonecrop of the Himalaya and adjacent China, recorded from south-central China (Xizang), the Indian Himalaya, Nepal and Bhutan, with around one hundred GBIF occurrences (a few extra-Himalayan records being cultivated or misattributed). It inhabits the highest open habitats, including alpine screes, rock crevices, gravelly slopes and the stony margins of the upper alpine zone, generally well above 4000 m. The photographed plant from the Shele-La in Bhutan at 4100 m, flowering in September, exemplifies its preference for exposed, frost-prone, mineral-rich substrates near the upper limit of vascular plant life.

The species is a small, glabrous, cushion- or mat-forming perennial succulent arising from a stout, branched, persistent caudex clothed in old leaf bases. The numerous short flowering stems bear crowded, small, fleshy, linear to oblong leaves with entire margins. The inflorescence is a compact terminal cyme of few flowers; as is typical of Rhodiola the plants are usually dioecious, with four- to five-merous flowers, the petals reddish, purplish or greenish, and the carpels erect, becoming spreading, beaked follicles at maturity that release minute seeds.

The GBIF backbone treats this name as doubtful, but it is here treated under the accepted name Rhodiola humilis within Rhodiola (Crassulaceae, subfamily Sempervivoideae), a genus segregated from Sedum and centred on the high mountains of Asia. Its succulent caudex, dwarf cushion form and crassulacean physiology are adaptations to drought, cold and intense radiation at extreme altitude. Like many Rhodiola, it may be gathered for traditional medicinal use; though not formally assessed, its slow growth and harvesting pressure suggest caution.

Author: (Hook. f. & Thomson) Fu · Sources: POWO (Kew), GBIF, Flora of China, Flora of Bhutan, Ohba monograph of Himalayan Sedoideae/Rhodiola (Crassulaceae)

Crassulaceae

Rhodiola sherriffii

by GP Jürgens

H. Ohba

BhutanPG2011 518
Bhutan Dem-Tso, 4500m June

Description

Rhodiola sherriffii is a rare, narrowly distributed alpine succulent of the Eastern Himalaya, recorded from Bhutan, the adjacent Indian states (Sikkim, Arunachal Pradesh), Nepal and southern Tibet (China); GBIF documents only about 20 occurrences, underscoring its restricted range and the relative inaccessibility of its habitat. It is a plant of the high alpine zone, typically growing above 4000 m, as illustrated near Dem-Tso in Bhutan at 4500 m, where it occupies open stony slopes, glacial moraine, rock crevices and gravelly fellfield. Like other members of the genus it tolerates intense insolation, frost and a short growing season, flowering in early summer (June) as snow recedes.

It is a small, glabrous, glaucous perennial herb arising from a thick, woody, scaly caudex and rootstock. Several short, erect or ascending flowering stems bear numerous fleshy, succulent leaves that are entire to obscurely toothed, sessile, oblong to obovate and crowded along the stem. The inflorescence is a dense, terminal, corymbose to capitate cyme. The flowers are usually unisexual (the genus being dioecious), 4-5-merous, with petals and sepals that are commonly dark red to purplish; the carpels are erect, maturing into small, erect follicles containing numerous minute seeds.

Named for the plant collector George Sherriff, who with Frank Ludlow explored Bhutan and southeastern Tibet, the species belongs to a Himalayan complex of red-flowered Rhodiola allied to R. bupleuroides and R. coccinea. The genus Rhodiola was segregated from Sedum on the basis of its perennial scaly caudex and predominantly dioecious flowers. Many Rhodiola species accumulate medicinally valued secondary metabolites and are harvested as adaptogens, exposing the genus to collection pressure. Given its small population number and high-elevation habitat, R. sherriffii is potentially vulnerable to climate-driven habitat contraction, though it has not been formally assessed.

Author: H. Ohba · Sources: POWO (Kew), GBIF, Flora of Bhutan, Flora of China, Ohba's monograph of Himalayan Crassulaceae (Rhodiola)

Crassulaceae

Rhodiola wallichiana

by GP Jürgens

(Hook.) Fu

Nepal 99 261 ergebnis
Nepal Kalomura 4000m, July
Sikkim2003 395 G556
Sikkim Zemu Valley 3400m August
Sikkim2003 480 P666
Sikkim Zemu Valley 3400m August

Description

Rhodiola wallichiana is a high-elevation succulent perennial of the Himalaya and Tibetan margins, native from Nepal and the Indian Himalaya through Sikkim and Bhutan into southern China, Pakistan and Afghanistan; the many European and North American GBIF records reflect cultivated and herbarium material rather than wild occurrence. It grows in the alpine and upper subalpine zone, on rocky slopes, cliff ledges, moraines and among boulders. The cited collections from Kalomura in Nepal at about 4000 m in July and the Zemu valley in Sikkim at 3400 m in August place it firmly in the summer-flowering high-mountain flora.

The plant arises from a stout, branched, woody caudex (rootstock) bearing several erect or ascending leafy flowering stems. The leaves are alternate, sessile, fleshy, linear-lanceolate to oblong, flat, with entire or finely toothed margins, densely clothing the stems. The inflorescence is a terminal corymbose cyme of numerous small flowers. The species is functionally dioecious; the flowers are typically four- to five-merous, with greenish-yellow to reddish petals, the staminate flowers bearing stamens twice the number of petals, and the pistillate flowers developing several erect follicles that ripen reddish and split to shed minute seeds.

Rhodiola, segregated from Sedum, comprises the rosette- and caudex-forming stonecrops of cold northern and montane regions. Like its relatives the genus accumulates protective metabolites, and several species are harvested as adaptogenic medicinals, placing wild Himalayan populations under collection pressure. Adapted to short alpine summers, intense radiation and cold, R. wallichiana is locally frequent within its range and not currently assessed as globally threatened.

Author: (Hook.) Fu · Sources: POWO (Kew), GBIF, Flora of China, Flora of Bhutan, Ohba's monographic studies of Himalayan Crassulaceae (Rhodiola)

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