Author

GP Jürgens

Hydrangeaceae

Deutzia corymbosa

by GP Jürgens

R.Br. ex G.Don

BhutanPG2011 820 01 01
Bhutan Chele-La, 3400m July

Description

Deutzia corymbosa is a flowering shrub of Himalayan temperate forests, with GBIF documenting 99 occurrences from India, China, Nepal and Bhutan, plus a few cultivated or vouchered records from Europe and North America. It grows on forest margins, shrubby slopes, rocky banks and clearings in the temperate to lower subalpine zone, often in mixed broadleaved and conifer forest. It was recorded on the Chele-La in Bhutan at about 3400 m in July, a high-summer flowering at the upper part of its range where the white corymbs are conspicuous against the montane scrub.

It is a deciduous shrub with erect to arching branches and exfoliating bark on the older stems. The leaves are opposite, ovate to ovate-lanceolate, acuminate, finely serrate, and clothed in stellate hairs that give the foliage a slightly rough texture characteristic of the genus. The inflorescence is a flattened, many-flowered corymb, as the epithet corymbosa indicates; each flower has five white, spreading petals, five sepals, ten stamens with the toothed or winged filaments typical of Deutzia, and three to four styles. The fruit is a small, hemispherical to top-shaped, several-valved capsule.

Deutzia (Hydrangeaceae) comprises shrubs of east Asia, Central America and the Himalaya, with a rich Sino-Himalayan representation and many ornamental species; the corymbose-inflorescenced group to which D. corymbosa belongs is distinctive within the genus. Widely grown and hybridised in horticulture, it is common across its broad native range and not of conservation concern. As an element of the temperate Himalayan shrub layer, it is of biogeographic interest within the disjunct east-Asian to Himalayan distribution pattern shown by many Hydrangeaceae.

Sources: POWO (Kew), GBIF, Flora of China, Flora of Bhutan, Annotated Checklist of the Flowering Plants of Nepal, Zaikonnikova's monograph of Deutzia (Hydrangeaceae)

Hydrangeaceae

Deutzia staminea

by GP Jürgens

R.Br. ex Wall.

Nepal 97 304 P605
Nepal Honggaon 2360m, May

Description

Deutzia staminea is a deciduous shrub distributed across the western and central Himalayas, from Pakistan through northern India and Nepal to Bhutan, with populations extending into southwest China and northern Myanmar. GBIF records approximately 390 occurrences, with the majority from India and Nepal. The species occupies dry to mesic slopes, open forests, scrublands, and rocky hillsides at elevations of 1,500–3,200 m. At Honggaon in central Nepal at 2,360 m, it inhabits open Pinus–Quercus forests and rocky banks, where it flowers prolifically in May during the pre-monsoon season.
Deutzia staminea is a deciduous shrub reaching 1.5–4 m in height, with greyish-brown bark that exfoliates in thin flakes on older stems. Leaves are opposite, ovate to lanceolate, 3–8 cm long, with serrate margins and a rough texture from stellate trichomes on both surfaces. The inflorescence is a terminal corymb or panicle of 5–20 flowers. Flowers are pentamerous, 12–18 mm in diameter, with white petals that are oblong-elliptic and spreading. The stamens, 10 in number, are distinctive: the filaments are broadly winged and toothed at the apex, exceeding the petals — a character reflected in the specific epithet 'staminea.' The fruit is a hemispheric capsule, 4–6 mm across, dehiscing by 3–4 valves and releasing numerous small seeds.
Deutzia staminea is the most widespread Himalayan representative of the genus and is distinguished from the closely related D. compacta by its prominently toothed stamen filaments and generally laxer inflorescences. The species serves as an important early-season nectar resource for pollinators in mid-elevation Himalayan landscapes, where relatively few shrubs are in flower during the pre-monsoon period. It is occasionally cultivated in European gardens and has been in cultivation since its introduction by Wallich in the early nineteenth century.

Author: R.Br. ex Wall. · Sources: POWO (Kew), GBIF, Flora of China Vol. 8, Flora of Pakistan Vol. 192, Polunin & Stainton: Flowers of the Himalaya (1984)

Diapensiaceae

Diapensia himalaica

by GP Jürgens

Hook.f. & Thomson

BhutanPG2011 447
Bhutan Jule-Tso, 4100m June

Description

Diapensia himalaica Hook.f. & Thomson is a high-alpine cushion plant of the Sino-Himalayan mountains, recorded from China, India, Nepal, Bhutan and Myanmar (CN, IN, NP, BT, MM), with GBIF documenting some 304 occurrences. It is a plant of the upper alpine and subnival belt, on exposed rocky ridges, gravelly slopes, moraines and turf margins, generally above 4000 m where wind exposure and a short growing season prevail. The Bhutanese material from Jule-Tso at 4100 m in June illustrates its early-summer flowering after snow-melt, when the cushions are studded with relatively large solitary flowers.

It forms a compact, evergreen, woody cushion of densely crowded shoots clothed in small, leathery, imbricate leaves. These are narrowly spathulate to oblong, sessile, with a thickened entire margin and a coriaceous texture resisting desiccation. The flowers are solitary and terminal on short stalks scarcely exceeding the cushion, actinomorphic and five-merous, with a persistent calyx and a campanulate to rotate corolla of fused white to pale pink petals; the five stamens are adnate to the corolla tube. The fruit is a small loculicidal capsule with numerous minute wind-dispersed seeds.

Diapensia is the type genus of the small, isolated family Diapensiaceae, an arctic-alpine lineage of ericalean affinity, and D. himalaica is the Himalayan vicariant of the circumboreal D. lapponica complex. The compact cushion habit is a classic adaptation to cold, wind-swept, nutrient-poor high mountains. Its biogeographic importance lies in linking the Himalayan high-alpine flora to arctic and boreal cushion-plant communities, and as a slow-growing specialist it is sensitive to climate change.

Author: Hook.f. & Thomson · Sources: POWO (Kew), GBIF, Flora of Bhutan Vol. 2, Flora of China Vol. 14, Flora of Nepal, Scott & Day monograph of the Diapensiaceae

Ranunculaceae

Dichocarpum adiantifolium

by GP Jürgens

(Hook.f. & Thomson) W.T.Wang & P.K.Hsiao

Nepal 97 310 G614
Nepal Honggaon 2300m May
Sikkim 2006 33 2 ergebnis
India West-Bengal Tonglu 3200m, May

Description

Dichocarpum adiantifolium is a slender woodland buttercup relative of the Sino-Himalayan region, distributed through Taiwan, China, India, Nepal, Bhutan and Myanmar, with the comparatively rich total of about 286 GBIF records. It grows in cool, shaded, humus-rich situations: moist temperate forest floors, mossy rocks, ravine banks and streamsides, generally between about 2000 and 3500 m. The collections illustrated, from Honggaon in Nepal at around 2300 m and Tonglu in West Bengal at about 3200 m, both in May, represent its typical spring-flowering forest habitat.

It is a delicate, glabrous perennial herb arising from a short rhizome. The leaves are mostly basal, long-petiolate and compound, divided into numerous small, thin, fan-shaped to obovate leaflets that recall the fronds of a maidenhair fern (Adiantum), hence the epithet. Slender scapes bear loose, few-flowered cymes of small flowers, each with five white, petaloid sepals and small tubular or two-lipped nectary petals, numerous stamens and usually two carpels. The diagnostic fruit is a pair of divergent, flattened follicles spreading widely at maturity, a feature reflected in the generic name (from the Greek for divided fruit).

Dichocarpum is a small east Asian and Himalayan genus segregated from Isopyrum and allied to Thalictrum and Aquilegia within the Ranunculaceae; D. adiantifolium was originally described under Isopyrum and later transferred by Wang and Hsiao. The paired spreading follicles and ferny foliage make it readily recognisable. It is a fairly widespread forest-understorey species and is not regarded as threatened, though as a shade-demanding mesophyte it depends on intact, humid temperate forest and would be sensitive to logging and forest fragmentation.

Author: (Hook.f. & Thomson) W.T.Wang & P.K.Hsiao · Sources: POWO (Kew), GBIF, Flora of China, Flora of Bhutan, Annotated Checklist of the Flowering Plants of Nepal, Wang & Hsiao Revision of the Genus Dichocarpum

Didymocarpinae

Didymocarpus aurantiacus

by GP Jürgens

C.B.Clarke

Sikkim2003 22 G26
Sikkim Rathong-Chu 1200 m, August

Description

Didymocarpus aurantiacus is an eastern Himalayan gesneriad recorded from India, Nepal and Bhutan, with around 33 occurrences concentrated in the wet, monsoon-drenched subtropical to lower temperate belt of Sikkim, Darjeeling and adjacent regions. It is a lithophyte and epipetric herb growing on shaded, moss-covered rocks, cliff faces and damp ravine walls within evergreen broad-leaved forest, typically between roughly 1000 and 2000 m. The illustrated material from the Rathong-Chu valley in Sikkim at 1200 m, flowering in August, reflects its main flowering during the rainy season, when the humid rock habitats it favours are kept constantly moist by mist and seepage.

It is a small perennial herb with a short rhizomatous base and crowded, opposite or subrosulate leaves. The lamina is ovate to elliptic, with a crenate-serrate margin, an acute to acuminate apex and a thinly hairy surface, the venation impressed above and prominent beneath. The inflorescence is an axillary cyme borne on a slender peduncle. The flowers have a tubular, lobed calyx and a tubular, somewhat ventricose corolla that is orange to orange-yellow (as the epithet aurantiacus indicates), two-lipped with a shorter upper and spreading lower lip. There are two fertile stamens with cohering anthers and staminodes; the gynoecium develops into the elongate, septicidal, two-valved capsule characteristic of the genus.

The input places this taxon under "Didymocarpinae", which is the subtribe within tribe Trichosporeae of the Gesneriaceae rather than a family; the species is correctly accommodated in the genus Didymocarpus. The name D. aurantiacus C.B.Clarke is accepted. As a narrow-ranged rock specialist tied to perhumid forest, it is dependent on intact, shaded microhabitats and is therefore potentially sensitive to deforestation and habitat drying, though it has not been formally assessed.

Author: C.B.Clarke · Sources: POWO (Kew), GBIF, Flora of Bhutan Vol. 2, Flora of Nepal, Weber Gesneriaceae of the World (monograph), Clarke Commelynaceae et Cyrtandreae Bengalenses

Didymocarpinae

Didymocarpus punduanus var. pulchrus

by GP Jürgens

(C.B.Clarke) Su.Datta & B.K.Sinha

This image has an empty alt attribute; its file name is Bhutan2012-485-1024x702.jpg
Bhutan Wangdi 2800m, September
Bhutan2012 486
Bhutan Wangdi 2800m, September

Description

Didymocarpus punduanus var. pulchrus is an eastern Himalayan member of the Gesneriaceae, known from the moist montane forests of Bhutan and the adjacent Himalaya. No georeferenced GBIF occurrences are currently available for this infraspecific taxon, reflecting its narrow circumscription and limited collecting. Like its relatives it is a saxicolous to terrestrial herb of shaded, humid habitats, growing on mossy rock faces, cliff ledges, ravine banks and damp forest slopes in the temperate zone. The photographed plant from Wangdi (Wangdue Phodrang) in Bhutan, at 2800 m and flowering in September, indicates a preference for cool, sheltered mid-montane sites with high humidity.

The plant is a small perennial herb, frequently with a short rhizomatous rootstock and opposite, ovate to elliptic leaves that are crenate-serrate and softly pubescent, with the bullate, sunken venation typical of the genus. The flowers are borne in axillary, pedunculate cymes; each has a tubular, somewhat two-lipped corolla, often purple to violet or pinkish, with a slightly oblique limb of five rounded lobes. There are two fertile stamens (the reduction characteristic of Didymocarpus) with cohering anthers, plus staminodes. The gynoecium develops into the elongate, narrowly cylindrical, septicidal capsule diagnostic of the genus, splitting to release numerous minute seeds.

The family placement given here as "Didymocarpinae" refers to the subtribe Didymocarpinae of the Gesneriaceae (tribe Trichosporeae), within which Didymocarpus is a large Asian genus centred on the Himalaya and Southeast Asia. This taxon, based on a Clarke epithet and recombined by Datta and Sinha, is treated at varietal rank; the source links to a Didymocarpus pulcher page, reflecting nomenclatural movement around the name. As a narrowly distributed forest endemic it is potentially of conservation interest but remains formally unassessed.

Author: (C.B.Clarke) Su.Datta & B.K.Sinha · Sources: POWO (Kew), GBIF, Flora of Bhutan, The Gesneriaceae of the Eastern Himalaya, A revision of Didymocarpus (Gesneriaceae)

Convolvulaceae

Dinetus racemosus

by GP Jürgens

(Roxb.) Sweet

Bhutan2012 1212
Bhutan Mo-Chu 1500m, October
Bhutan2015 565
Bhutan Mo-Chu 1500m, October
Bhutan2015 566
Bhutan Mo-Chu 1500m, October

Description

Dinetus racemosus is a twining climber of the morning-glory family widely distributed across the Himalaya, Indo-Burma and South-East Asia. GBIF records, numbering over 900, place it in India, Nepal, Bhutan and China through Myanmar, Thailand, Laos, Vietnam and Malaysia to Indonesia and Timor-Leste, with cultivated or naturalised records elsewhere. It occupies forest margins, thickets, hedgerows, scrubby roadsides and clearings in subtropical to warm-temperate zones, where it scrambles vigorously over shrubs and small trees. The photographed plant from the Mo Chu valley in Bhutan, at about 1500 m and flowering in October, illustrates its autumn-flowering habit in mid-elevation valley vegetation, where its conspicuous white inflorescences appear after the monsoon.

The species is a perennial, herbaceous to slightly woody, left-twining liana with slender, often pubescent stems. The leaves are alternate, long-petiolate, broadly ovate to ovate-cordate with a deeply cordate base and acuminate apex, the lamina entire and softly hairy. The flowers are borne in elongate, many-flowered, axillary and terminal racemes or panicles, a distinctive feature in a family more usually cymose. Each flower is small, with a five-lobed calyx and a white, broadly funnelform to subcampanulate, five-angled corolla. After flowering the calyx lobes enlarge markedly and become membranous, accrescent wings that surround the small, indehiscent, one- to few-seeded fruit, serving as a wind-dispersal organ.

Dinetus belongs to the tribe Poraneae of Convolvulaceae, a group characterised by racemose inflorescences and accrescent, wing-like fruiting sepals, and the species has long been known under the synonyms Porana racemosa and Porana grandiflora; modern treatments recognise the segregate genus Dinetus. The accrescent calyx wings are a clear adaptation to anemochory, dispersing the light fruits on the wind. The plant is common and ecologically resilient across its broad range and is of no conservation concern; it is locally appreciated as an ornamental for its profuse white autumn flowering and is occasionally used in traditional medicine.

Author: (Roxb.) Sweet · Sources: POWO (Kew), GBIF, Flora of China Vol. 16, Flora of Bhutan Vol. 2, Flora of Nepal, Flora of Pakistan, Staples' systematics of Convolvulaceae (Poraneae)

Caprifoliaceae

Dipsacus inermis

by GP Jürgens

Wall.

Bhutan2015 479
  Bhutan Pele-La 3200m, October
Garw 2005 272 ergebnis
India Garhwal Kunol 2450m, September

Description

Dipsacus inermis is a tall biennial or short-lived perennial herb widely distributed through the temperate Himalaya and into China and Myanmar, with naturalised and casual occurrences recorded as far afield as Britain, Ireland, Portugal, Turkey and the United States among its 830-odd documented records. Within its native range it grows in forest clearings, along streamsides, in damp meadows and on disturbed slopes from about 1800 to 3500 m. The illustrated plants come from Pele-La in Bhutan at 3200 m in October and from Kunol in Garhwal, India, at 2450 m in September, the latter date capturing the fruiting season.

The species develops a furrowed, sparsely prickly to nearly unarmed stem (whence the epithet inermis), distinguishing it from the strongly spiny teasels. Leaves are opposite, the lower petiolate and often lyrate-pinnatifid, the cauline sessile and lanceolate, frequently connate at the base. The inflorescence is a dense ovoid to globose capitulum subtended by linear involucral bracts; the receptacular bracts are awned. Individual flowers are small, with a four-lobed whitish to pale purple corolla and an epicalyx surrounding each floret; the calyx is cup-shaped and the fruit an achene crowned by the persistent calyx.

Formerly placed in the family Dipsacaceae, the genus is now subsumed within an enlarged Caprifoliaceae following molecular reclassification. The plant is insect-pollinated and its seed-heads provide forage for granivorous birds. It is a vigorous coloniser of disturbed ground, accounting for its sporadic naturalisation outside Asia; it carries no conservation concern across its extensive native distribution.

Author: Wall. · Sources: POWO (Kew), GBIF, Flora of China, Flora of Bhutan, Flowers of the Himalaya, Caprifoliaceae monograph

Colchicaceae

Disporum cantoniense

by GP Jürgens

(Lour.) Merr.

Bh2008 447 G698
Bhutan Samtengang 2040m, May
Sikkim2004 113 P194
India West-Bengal, Utaray 2100m April
Nepal 97 373 P733
Nepal Arun-Valley 1750m, May

Description

Disporum cantoniense (Lour.) Merr. is a rhizomatous perennial herb of the Colchicaceae with a wide distribution across the Himalaya, mainland and insular Southeast Asia and East Asia. GBIF (nearly 4,000 occurrences) documents it from China, India, Nepal, Bhutan, Thailand, Taiwan, Japan, Vietnam, Myanmar, Malaysia, Indonesia and Sri Lanka, where it grows in shaded broad-leaved and mixed forest, on forest margins, shaded banks and among scrub. It occupies a broad montane belt; the records from Samtengang in Bhutan (2,040 m), Utaray in West Bengal (2,100 m) and the Arun Valley in Nepal (1,750 m), flowering in April–May, illustrate its spring anthesis in mid-elevation Himalayan forest understorey.

The plant arises from a short, knotty rhizome bearing fleshy roots and produces erect, branched aerial stems up to a metre or more tall. The leaves are alternate, ovate-lanceolate to lanceolate, with conspicuous arcuate-parallel venation and somewhat clasping or shortly petiolate bases. The flowers hang in terminal, drooping few-flowered umbel-like clusters at the branch tips; each is narrowly campanulate with six free, spreading to recurved tepals, white, greenish or tinged purple, the tepals saccate or shortly spurred at the base. There are six stamens and a superior ovary; the fruit is a globose, dark blue-black to purplish berry containing few seeds.

Disporum, long placed in Liliaceae and later Convallariaceae, is now firmly assigned to the Colchicaceae on molecular and morphological grounds, distinct from the New World Prosartes. D. cantoniense is a polymorphic, widespread species with several recognised varieties, and the variation in flower colour and stature has generated considerable taxonomic literature. Ecologically it is a characteristic shade-tolerant geophyte of Asian temperate and subtropical forests, with berries dispersed by birds.

Author: (Lour.) Merr. · Sources: POWO (Kew), Flora of China Vol. 24, Flora of Bhutan Vol. 3, GBIF, Conran & Tamura: Colchicaceae in The Families and Genera of Vascular Plants

Colchicaceae

Disporum leucanthum

by GP Jürgens

H.Hara

Bhutan2014 212
Bhutan Trashyangtse 2100m, May
Bhutan2014 215
Bhutan Trashyangtse 2100m, May

Description

Disporum leucanthum is a woodland perennial of the eastern Himalaya and adjacent regions, recorded from China, India, Bhutan, Myanmar and Nepal, with only some 35 occurrences in GBIF, reflecting both a relatively restricted range and limited collecting. It is a plant of shaded, moist broad-leaved and mixed forest, forest understorey and shaded streamsides, typically in the warm to cool temperate belt. The individual photographed at Trashyangtse in eastern Bhutan at 2100 m in May, flowering in spring under forest cover, is characteristic of its preference for humid, sheltered montane woodland where deep humus and dappled shade prevail.

The species is an erect, sparingly branched perennial herb arising from a short, creeping rhizome with fibrous roots. The slender stems bear alternate, ovate to ovate-lanceolate leaves that are conspicuously parallel-veined, entire and shortly petiolate to subsessile, with a rounded to subcordate base and acuminate apex. The flowers are pendent and borne singly or in small clusters at the branch tips; they are narrowly campanulate to tubular, with six free, white tepals (as the epithet indicates) that are sometimes greenish-tinged, each tepal spurred or saccate at the base. There are six stamens, and the superior ovary develops into a small, fleshy, globose to ovoid berry that ripens dark, containing several seeds.

Disporum is an East Asian genus now placed in the family Colchicaceae following molecular reappraisal, having formerly been treated within Liliaceae or Convallariaceae; the North American fairy-bells once included here are now separated as Prosartes. D. leucanthum belongs to the Sino-Himalayan assemblage of the genus, distinguished among its relatives by floral and tepal characters. The berries are bird-dispersed. Owing to its comparatively narrow distribution and the small number of documented records its populations warrant monitoring, though it is not formally assessed as threatened.

Author: H.Hara · Sources: POWO (Kew), GBIF, Flora of China Vol. 24, Flora of Bhutan Vol. 3, Flora of Nepal, A Revision of the Genus Disporum (Colchicaceae)