Author

GP Jürgens

Brassicaceae

Draba bhutanica

by GP Jürgens

H.Hara 

BhutanPG2011 418
Bhutan Ludlow-Sherriff-Trail Warrtlang-La, 4400m June

Description

Draba bhutanica H.Hara is a narrowly distributed alpine crucifer recorded only from Bhutan and adjacent China (gbif_countries: BT, CN), with a mere 13 occurrences in GBIF, marking it as a rare Eastern Himalayan high-mountain endemic. It occupies the upper alpine zone, growing on open stony slopes, scree, gravelly ridges and rock crevices near the limits of vascular plant life. The image record from the Ludlow-Sherriff Trail at Warrtlang-La in Bhutan at 4400 m, in June, situates it in the early-summer high alpine, where short-statured perennials flower briefly after snowmelt on exposed, well-drained ground.

It is a small, low, tufted or cushion-forming perennial herb, typically clothed in the branched, stellate or forked trichomes characteristic of the genus, giving a greyish indumentum. The leaves are small, entire to slightly toothed, crowded into basal rosettes. The flowering scapes are short and bear few-flowered terminal racemes. The flowers conform to the cruciferous plan, with four sepals, four clawed yellow (or whitish) petals in a cross, and tetradynamous stamens. The fruit is a small silicula, ovate to elliptic and somewhat flattened, dehiscing by two valves to release several seeds.

Draba is a large, predominantly arctic-alpine genus, and its Sino-Himalayan species are taxonomically intricate; D. bhutanica has been associated with the segregate Chrysobraya, reflecting unsettled generic limits in the region. Its cushion habit and dense indumentum are classic adaptations to cold, high-radiation, desiccating alpine environments. Given its extremely restricted range and few records, the species is of considerable conservation and biogeographic interest as a Bhutanese alpine endemic.

Author: H.Hara · Sources: POWO (Kew), GBIF, Flora of China (Brassicaceae), Flora of Bhutan, Al-Shehbaz systematic studies of Himalayan Draba and Cruciferae

Brassicaceae

Draba gracillima

by GP Jürgens

Hook.f. & Thomson

Bh09 156 G278
Bhutan Labana 4130m, June

Description

Draba gracillima is a slender alpine whitlow-grass of the Himalaya, distributed across the Indian Himalaya, Nepal, south-central China (Xizang) and Bhutan, with around one hundred and twenty-six GBIF records reflecting a continuous high-mountain range. It occupies alpine meadows, stony slopes, rock ledges, screes and crevices above the treeline, generally between about 3500 and 4500 m. The photographed plant from Labana in Bhutan at 4130 m, flowering in June, typifies its early-summer flowering and its preference for the open, well-drained mineral soils of the upper alpine zone.

The species is a slender, tufted perennial arising from a branched caudex and forming small basal rosettes of leaves, the lamina narrowly oblanceolate to spathulate and clothed, as is typical of Draba, in simple, forked and stellate hairs. The flowering stems are filiform and few-leaved, giving the plant its delicate, gracile appearance. The inflorescence is a lax raceme of small flowers with four free yellow (fading whitish) petals in the cruciferous arrangement and six tetradynamous stamens. The fruit is a small, flattened, lanceolate to elliptic silicula on a slender pedicel, dehiscing to release several seeds per locule.

Draba gracillima is an accepted species of the large genus Draba (Brassicaceae, tribe Arabideae), one of the most species-rich and taxonomically intricate genera of arctic and alpine regions, characterised by variable trichome morphology of diagnostic value. Its cushion-forming caudex, dense indumentum and short silicula are adaptations to cold, wind-exposed, high-radiation alpine habitats. The species is widespread and not regarded as threatened, although its specialised high-altitude niche is sensitive to climate-driven range shifts.

Author: Hook.f. & Thomson · Sources: POWO (Kew), GBIF, Flora of China, Flora of Bhutan, Jordal & Al-Shehbaz revision of Draba (Brassicaceae monograph)

Brassicaceae

Draba oariocarpa

by GP Jürgens

O.E.Schulz

BhutanPG2011 656
Bhutan Thitha-Tso 4360m, July

Description

Draba oariocarpa is a high-alpine crucifer of the eastern Himalaya, known principally from Bhutan and adjoining areas, where GBIF holds only a single occurrence record, reflecting both its narrow distribution and its remote habitat. It is a plant of open alpine screes, stony slopes, moraines and frost-disturbed gravels of the upper alpine and subnival zones, generally above 4000 m. The photograph from the Thitha Tso in Bhutan at about 4360 m in July shows the species flowering in the brief high-summer window in its harsh, exposed lakeside scree habitat.

The plant is a small, tufted or cushion-forming perennial arising from a branched caudex topped by rosettes of leaves. The leaves are small, oblong to spathulate, entire or nearly so, and clothed in the stellate and simple hairs characteristic of the genus, giving a greyish, roughened texture. From the rosettes arise short, leafless or few-leaved scapes bearing a compact raceme of small flowers; these have four sepals and four yellow (sometimes fading whitish) petals in the cruciform arrangement typical of the Brassicaceae, with six stamens. The fruit, alluded to in the epithet oariocarpa (egg-fruited), is a small, ovate to elliptic, somewhat flattened silicula containing several seeds.

Draba is a very large, predominantly arctic-alpine genus of the Brassicaceae, taxonomically intricate owing to widespread polyploidy, apomixis and minor morphological differentiation, so that many narrowly defined species and synonyms have been described from the Himalaya and Tibet. The dwarf cushion habit and dense indumentum are classic adaptations to the cold, desiccating and intensely irradiated subnival environment. Given its apparently very restricted range and few documented collections, D. oariocarpa is poorly known and warrants further field assessment of its distribution and status.

Author: O.E.Schulz · Sources: POWO (Kew), GBIF, Flora of Bhutan, Flora of China, Annotated Checklist of the Flowering Plants of Nepal, Al-Shehbaz's systematic studies of Draba and the Brassicaceae

Brassicaceae

Draba tibetica

by GP Jürgens

Hook.f. & Thomson

Sikkim2004 139 P241
Sikkim/India Singalila 3800m April

Description

Draba tibetica is a cushion- to mat-forming alpine crucifer with a wide distribution across the Himalaya, Tibetan Plateau and the mountains of Central Asia. GBIF records around 173 occurrences spanning India, Pakistan, Tajikistan, Uzbekistan, China, Afghanistan, Kazakhstan, Kyrgyzstan and Nepal. It colonises stony alpine turf, rock ledges, fellfield and the gravelly margins of seasonal snowmelt, generally between 3500 and 5000 m. The illustrated population was found along the Singalila ridge of Sikkim, India, at 3800 m in April, flowering early as the higher slopes begin to thaw on well-drained, base-rich substrates.

The plant develops a woody, much-branched caudex bearing dense rosettes of small, oblanceolate to spathulate leaves clothed in stellate and simple hairs that give a greyish indumentum. Erect, leafless or few-leaved scapes rise above the foliage carrying short racemes of small flowers. The four petals are yellow, fading paler with age, exceeding the hairy sepals; the six tetradynamous stamens surround a superior ovary. The fruit is a flattened, ovate to elliptic silicula, glabrous or sparsely pubescent, held on ascending pedicels and splitting to release numerous minute seeds in two rows.

Draba (Brassicaceae) is a large, taxonomically intricate genus centred on arctic and alpine habitats, and D. tibetica belongs to the yellow-flowered Himalayan-Tibetan assemblage where cushion habit and indumentum vary clinally, complicating delimitation. GBIF treats the name as accepted. As a hardy pioneer of unstable high-altitude ground it is locally common and faces no recognised conservation concern across its extensive range.

Author: Hook.f. & Thomson · Sources: POWO (Kew), GBIF, Flora of China, Flora of Pakistan, Al-Shehbaz revisions of Draba (Brassicaceae)

Lamiaceae

Dracocephalum wallichii

by GP Jürgens

Sealy

BhutanPG2011 790 01 01
Bhutan Chele-La, 3800m July
BhutanPG2011 791 01 01
Bhutan Chele-La, 3800m July

Description

Dracocephalum wallichii is a Himalayan dragonhead recorded from India, China (Xizang), Nepal and Bhutan, with GBIF holding around 175 occurrences across the high eastern and central ranges. It is a plant of the alpine zone, growing on open stony slopes, gravelly meadows, scree and grassy banks typically between about 3500 and 4500 m. The photographed material from the Chele-La in western Bhutan at 3800 m, flowering in July, is characteristic: at this high pass the species blooms in the brief summer window after snowmelt, exploiting well-drained, sunny ground among the alpine turf and rock where competition from taller vegetation is limited.

It is a perennial herb with a woody rootstock giving rise to several erect or ascending quadrangular stems. The leaves are opposite, oblong to narrowly ovate, the margin crenate to incised, and often somewhat aromatic, as is general in the genus. The inflorescence is a dense, head-like to interrupted terminal spike of verticillasters subtended by conspicuous, often spine-toothed and ciliate floral bracts that are a notable feature of the species. Each flower has a tubular, two-lipped calyx and a strongly two-lipped corolla coloured blue to violet-purple, the hooded upper lip arching over the four didynamous stamens and the lower lip spreading and three-lobed as a landing platform for bees. The fruit comprises four smooth nutlets enclosed in the persistent calyx.

The species was described by Sealy and honours Nathaniel Wallich, an early collector of Himalayan plants. Dracocephalum is a genus of the temperate northern hemisphere centred on central Asia, well represented in alpine and steppe habitats; D. wallichii is one of its few truly Himalayan-alpine members and is distinguished by its bracteal armature and dense spike. Pollinated chiefly by bumblebees, it is a typical short-season alpine perennial, and being widespread in remote high terrain it is of no immediate conservation concern.

Author: Sealy · Sources: POWO (Kew), GBIF, Flora of China, Flora of Bhutan, Annotated Checklist of the Flowering Plants of Nepal, Budantsev revision of the genus Dracocephalum

Droseraceae

Drosera peltata

by GP Jürgens

Thunb.

Sikkim2011 185
Sikkim Lachung 2600m, June
Nepal 99 996 ergebnis
West-Nepal Juphal 2550m, July

Description

Drosera peltata is one of the most widely distributed of all sundews, a carnivorous herb ranging from Australia and New Zealand through East and Southeast Asia to the Himalaya, with GBIF holding an exceptional 32363 occurrences across Australia, China, Japan, India, Nepal, Thailand, Indonesia, the Philippines, Korea and many further countries. In the Himalaya it grows in open, wet, nutrient-poor situations: boggy grassland, mossy banks, seepage slopes, marshy meadows and damp roadside cuttings, generally between 1500 and 3000 m. The localities cited for the image, Lachung in Sikkim at about 2600 m in June and Juphal in West Nepal at around 2550 m in July, are typical mid-montane wet-meadow sites where the plant flowers during the early monsoon.

Unlike the rosette-forming sundews, D. peltata is an erect, often tuberous-rooted herb whose slender stem bears alternate, peltate to lunate leaves on long petioles. The leaf blades are crescent-shaped and clothed on their margins and upper surface with stalked glandular hairs (tentacles) tipped with glistening mucilaginous droplets that entrap small insects; the tentacles then bend inward and the leaf secretes enzymes to digest the prey. Basal rosette leaves may be present at germination but wither as the stem elongates. The inflorescence is a one-sided raceme of small white to pinkish five-merous flowers, opening in bright sunshine, and the fruit is a small capsule with numerous minute seeds.

Droseraceae are carnivorous, and the tuberous, stem-forming peltata complex constitutes a distinctive lineage within Drosera that has been variously subdivided into segregate species and subspecies by different authors, making it one of the more taxonomically contentious sundew groups. Insect capture supplies nitrogen and phosphorus otherwise scarce in the acidic, waterlogged soils it inhabits, and the underground tuber permits dormancy through dry or unfavourable seasons. Given its enormous geographic range the species as a whole is of no conservation concern, although individual Himalayan wetland populations are locally susceptible to drainage and habitat loss.

Author: Thunb. · Sources: POWO (Kew), GBIF, Flora of China Vol. 8, Flora of Bhutan Vol. 1, Flora of Nepal, Lowrie Carnivorous Plants of Australia Magnum Opus

Caryophyllaceae

Drymaria cordata

by GP Jürgens

Willd. ex Schult.

Bhutan2012 806 Kopie

Description

Drymaria cordata, the heartleaf or tropical chickweed, is a pantropical weed of Neotropical origin now naturalised throughout the warmer regions of the world, with nearly 14,000 GBIF occurrences spanning the Americas (United States, Brazil, Mexico, Colombia, Ecuador, Peru, Panama), Africa (South Africa, Cameroon, Tanzania, the Congo basin, Réunion), tropical Asia (Taiwan, China, India, Indonesia) and Australia and Papua New Guinea. It is a ubiquitous colonist of moist shaded ground – forest floors, plantations, gardens, roadsides and stream banks – from the lowlands into the lower hills, and in Bhutan, the source of the cited image, it occurs as a common weed of cultivated and disturbed warm-temperate sites.

It is a slender, straggling annual or short-lived perennial with weak, diffusely branched stems that root at the lower nodes and form loose tangles. The leaves are opposite, broadly ovate to orbicular-cordate, thin, three- to five-veined from the base, with small membranous stipules characteristic of the tribe. The flowers are tiny, borne in lax leafy-bracted cymes; each has five free green sepals, five deeply bifid white petals shorter than the sepals, few stamens and a superior ovary. The fruit is a small ovoid capsule splitting into three valves to release minute, tuberculate, horseshoe-shaped seeds, which together with glandular hairs aid epizoochorous dispersal.

Within Caryophyllaceae, Drymaria is allied to Stellaria but distinguished by its stipulate, broad cordate leaves and bifid petals. D. cordata is a notorious tropical agricultural weed, dispersed clinging to clothing, animals and soil, and is of management rather than conservation concern.

Author: Willd. ex Schult. · Sources: POWO (Kew), GBIF, Flora of China, Flora of Bhutan, Flora of Tropical East Africa, Duke monograph of Drymaria

Lythraceae

Duabanga grandiflora

by GP Jürgens

(Roxb. ex DC.) Walp.

Nepal 97 52 P78
Nepal Mewa-Khola 1150m April
Nepal 97 53 P79
Nepal Mewa-Khola 1150m April
Nepal1992 77 P110 ergebnis
Nepal Sokathum1460m March 

Description

Duabanga grandiflora (Roxb. ex DC.) Walp. is a large, fast-growing evergreen tree of the Lythraceae distributed through the Indo-Himalayan and Southeast Asian tropics, native from India, Nepal, Bhutan and Bangladesh through Myanmar, Thailand, Laos, Vietnam, Malaysia and Indonesia into SW China, with around 712 georeferenced records and scattered introductions elsewhere. It is a characteristic tree of moist tropical and subtropical forest, particularly along rivers, in ravines and on alluvial flats, often a pioneer of streamside and secondary forest in regions of high rainfall. The photographed trees from Mewa-Khola at about 1,150 m in April and Sokathum at about 1,460 m in March in eastern Nepal lie at the upper, lower-montane end of its altitudinal range, which extends down into the lowland tropics.

It is a tall tree with a spreading crown and conspicuously horizontal, drooping branches. The leaves are opposite, large, oblong to oblong-lanceolate, leathery, with an obtuse to cordate base and entire margins, glabrous and prominently pinnately veined. The large, showy flowers are borne in few-flowered terminal cymes; each has a thick campanulate calyx of (four to) six fleshy lobes, white obovate petals, and very numerous stamens. The superior to half-inferior ovary develops into a hard, leathery, many-celled capsule that splits by valves to release abundant small seeds.

Duabanga is a small Indo-Malesian genus formerly segregated in its own family Duabangaceae but now placed within an enlarged Lythraceae. The night-opening flowers with their massed stamens are bat- and moth-pollinated, and the light, soft wood is locally used for boxes, matchwood and plywood. Widespread and often common as a riparian pioneer, the species is not considered threatened.

Author: (Roxb. ex DC.) Walp. · Sources: POWO (Kew), Flora of China Vol. 13, Flora of Bhutan Vol. 2, GBIF, Graham et al.: Phylogeny of Lythraceae (2005)

Asteraceae

Dubyaea hispida

by GP Jürgens

DC.

Bhutan2012 56
Bhutan Shele-La, 4000m September

Description

Dubyaea hispida is an alpine member of the lettuce tribe (Cichorieae) ranging across the eastern and central Himalaya into south-western China, with reliable records from Nepal, India, Bhutan, Myanmar, Pakistan and China (Xizang, Yunnan, Sichuan); extra-regional points in Austria and Great Britain among the 544 occurrences represent cultivated or misattributed material rather than native range. It grows in moist alpine meadows, scrub margins, rocky slopes and streamsides, typically between about 3000 and 4300 m. The plant figured from the Shele-La pass in Bhutan at roughly 4000 m in September reflects its characteristic late-season flowering in cool, humid high-mountain habitats.

The species is a perennial herb with a short rhizome and erect, hispid stems clothed, like the peduncles and involucres, in spreading blackish or purplish multicellular hairs. The leaves are thin, oblong to lyrate-pinnatifid, with a large terminal lobe and a winged, amplexicaul petiole base; the upper leaves are reduced. The capitula are several, nodding in a loose corymb, with an involucre of imbricate, hispid phyllaries. The florets are all ligulate and yellow, as in the milky-juiced Cichorieae. The cypselae are narrowly fusiform, ribbed and slightly narrowed above, bearing a pappus of soft, white, finely barbellate bristles.

Dubyaea is a small Sino-Himalayan genus of perhaps a dozen species centred on the eastern Himalaya and Hengduan Shan, segregated from the related Crepis and Soroseris by its nodding heads, dark-hispid indumentum and distinctive achene and pappus characters. The nodding capitula and abundant glandular-setose vestiture are adaptations to wet alpine conditions, sheltering florets from rain. As a widespread high-elevation species across multiple countries, D. hispida is not considered threatened, although it is naturally restricted to the narrow alpine belt.

Author: DC. · Sources: POWO (Kew), GBIF, Flora of China Vol. 20-21, Flora of Bhutan, Flora of Nepal, Stebbins Cichorieae of the Himalaya

Verbenaceae

Duranta erecta

by GP Jürgens

L.

Bhutan2015 508
Bhutan Phobjika 2800m, October

Description

Duranta erecta, commonly called golden dewdrop or pigeon berry, is native to the Neotropics, ranging from Mexico, the Caribbean and Central America through tropical South America to Argentina and Brazil. It has, however, become one of the most widely cultivated and naturalised ornamental shrubs in warm regions worldwide, a fact reflected in its enormous GBIF tally of over nineteen thousand occurrences spanning the Americas, Asia, Africa and Australia. In the Himalaya it occurs only as a cultivated and locally escaping plant; the individual photographed at Phobjika in Bhutan at 2800 m in October represents such a planting in a temperate valley, well above the species' tropical comfort zone, where it is grown as a hedge or garden ornamental and flowers and fruits abundantly in the warm season. It thrives in disturbed ground, gardens, roadsides and waste places, and in many tropical countries is regarded as an invasive weed.

The plant is an evergreen, often spreading shrub or small tree to several metres, with slender, arching, sometimes pendulous and frequently spiny branches that may be four-angled when young. The leaves are opposite or whorled, elliptic to obovate, entire to toothed in the upper half, and light green. The flowers are borne in slender terminal and axillary racemes; the tubular corolla is pale blue to lavender (occasionally white), with five spreading, slightly unequal lobes. The fruit is a glossy, rounded, yellow to orange drupe enclosed by the persistent, beaked calyx, borne in showy pendent clusters; the berries and foliage contain saponins and are toxic to humans and livestock, though birds disperse the seeds freely.

Duranta is a small genus traditionally placed in the Verbenaceae, and D. erecta is its most familiar species, prized horticulturally for its long flowering season, attractive golden fruits and several variegated and golden-leaved cultivars. Its ornamental virtues are matched by a significant ecological downside: through bird-mediated seed dispersal it has become a serious environmental weed in parts of Australia, southern Africa and the Pacific. Its presence in the high Bhutanese Himalaya illustrates the global reach of horticultural commerce, and although frost limits its persistence at such elevations, its weediness elsewhere makes it a species of note for biosecurity rather than conservation.

Author: L. · Sources: POWO (Kew), GBIF, Flora of China Vol. 17, Flora of Bhutan Vol. 2 Part 2, Flora of Nepal, Flora of Pakistan, A Generic Revision of the Verbenaceae (Harold N. Moldenke)