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Bhutan

Flowers of Bhutan — 1326 plant species documented across the Bhutanese Himalaya, from dense broadleaf and conifer forests to alpine scrub and meadows. Bhutan’s largely intact wilderness shelters an exceptional diversity of orchids, rhododendrons, primulas and Himalayan poppies, many of them regional endemics. Each species page includes a botanical description, distribution, habitat and flowering time, with the original photograph and its recorded altitude and locality.

Didymocarpinae

Didymocarpus podocarpus

by G & P Jürgens

C.B.Clarke

BhutanPG2011 78 ergebnis 1
Bhutan Menchuang, 2800m June

Description

Didymocarpus podocarpus is an eastern Himalayan gesneriad recorded from Nepal (NP), India (IN) and Bhutan (BT), with 59 GBIF occurrences reflecting its relatively localised montane distribution. It is a lithophyte and epiphyte of shaded, humid temperate forest, growing on moss-covered rocks, cliff faces and tree trunks where atmospheric humidity is high, typically in the 2000-3000 m belt. The illustrated material was gathered at Menchuang in Bhutan at about 2800 m in June, during the early monsoon when the genus comes into flower.

It is a perennial herb with a short rhizomatous base and erect to ascending stems bearing opposite or whorled leaves clustered toward the apex. The leaf blades are ovate to elliptic, crenate-serrate at the margin, and often somewhat fleshy with sparse hairs. The inflorescence is an axillary cyme of several flowers; the calyx is tubular and shortly lobed, while the corolla is tubular and two-lipped with a spreading limb in shades of purple to violet. Only two stamens are fertile, a diagnostic feature of Didymocarpus, the anthers cohering in pairs. The fruit is a slender, elongate, podocarpic (long-pointed) capsule that dehisces to release numerous minute seeds, the epithet alluding to this fruit form.

Didymocarpus is a large Asian genus centred on the Sino-Himalayan and Southeast Asian region, traditionally placed in subtribe Didymocarpinae of Gesneriaceae, the rank cited here verbatim as the family field. Many species are narrow-range rock specialists vulnerable to habitat disturbance, and several Himalayan taxa, including this one, are of biogeographic interest as components of the moist broadleaf forest gesneriad flora.

Author: C.B.Clarke · Sources: POWO (Kew), GBIF, Flora of Bhutan, Flora of Nepal, The Gesneriaceae of the Indian subcontinent, Monograph of the genus Didymocarpus (Weber & Burtt)

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)

Orchideaceae

Dienia cylindrostachya 

by G & P Jürgens

Lindl.

Nepal 99 891 ergebnis
West-Nepal Suli-Khola 2900m, July

Description

Dienia cylindrostachya is a terrestrial orchid distributed across the Himalaya and adjacent montane Asia, recorded from India, Nepal, Bhutan, China, Hong Kong, Myanmar and Pakistan, with GBIF documenting some 98 georeferenced occurrences. It favours humus-rich, shaded forest floors, mossy banks and damp grassy slopes in the temperate zone, typically between about 1500 and 3000 m. The photographed plant was found in West Nepal along the Suli-Khola at 2900 m in July, an elevation and season that coincide with its summer flowering during the monsoon, when soil moisture and atmospheric humidity are at a maximum.

The species is a small, glabrous herb arising from a fleshy, ovoid pseudobulb or thickened stem-base. It bears a few thin, plicate, ovate-elliptic to lanceolate leaves that are membranous and sheathing at the base. The inflorescence is an erect, slender, densely many-flowered cylindrical raceme, from which the epithet derives, carrying numerous minute, non-resupinate flowers in shades of greenish-yellow to purplish. The sepals and petals are small and spreading; the lip is broad, often auriculate or saccate at the base, and the column is short and stout. The fruit is a small, ellipsoid, ribbed capsule releasing dust-like seeds.

Long placed in Malaxis, the species is now treated in Dienia (Malaxidinae, Epidendroideae), a segregate distinguished by non-resupinate flowers and column structure. The family is rendered "Orchideaceae" in the source but the taxon belongs to the Orchidaceae. As an easily overlooked terrestrial of intact temperate forest, it is sensitive to deforestation, though its wide Asian range affords some resilience.

Author: Lindl. · Sources: POWO (Kew), GBIF, Flora of Nepal, Flora of China, Flora of Bhutan, Genera Orchidacearum (Pridgeon et al.)

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)

Dioscoreaceae

Dioscorea bulbifera

by G & P Jürgens

L.

Bhutan2015 172
Bhutan Zhemgang 1000m, October

Description

Dioscorea bulbifera, the air potato or aerial yam, is a widely distributed twining vine of the Old World tropics, native across tropical Africa and Asia and now pantropically naturalised, including invasive populations in the southern United States, the Pacific and the Neotropics. It is among the most heavily recorded yams, GBIF holding over 16,000 occurrences. In the Himalaya it grows in subtropical forest, forest margins, thickets and disturbed ground at low to middle elevations. The plant from Zhemgang in central Bhutan at 1000 m in October occupies this warm foothill zone, where its aerial tubers ripen toward the season's end.

It is a herbaceous perennial climber arising from an underground tuber, the slender stems twining to the left (sinistrorse) and bearing in the leaf axils the diagnostic rounded to angular aerial bulbils that give the plant its names and serve as its chief means of propagation. The leaves are alternate, broadly cordate-ovate with a deeply notched base and long acuminate apex, palmately veined and long-petiolate. It is dioecious: the minute flowers are borne in slender pendulous spikes, staminate clustered and pistillate more lax, with a perianth of six tepals; the fruit, where set, is a three-winged loculicidal capsule with winged seeds, though sexual reproduction is often supplanted by the prolific bulbils.

Dioscorea, the type genus of Dioscoreaceae, is a large pantropical genus of economically vital yams. D. bulbifera is enormously variable, comprising numerous cytotypes and forms; some strains are cultivated for edible tubers while others are bitter and toxic, containing the sapogenin diosgenin and the toxic principle dioscorine. Its facility for clonal spread by bulbils has made it a notorious invasive weed beyond its native range, though within the Himalaya it is a common, unremarkable component of the disturbed subtropical flora.

Author: L. · Sources: POWO (Kew), GBIF, Flora of China Vol. 24, Flora of Bhutan Vol. 3, Annotated Checklist of the Flowering Plants of Nepal, Burkill account of Asiatic Dioscoreaceae

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 calcaratum

by G & P Jürgens

D.Don

Nepal 2009 101 ergebnis
Nepal Helambu Samathang 2410, May

Description

Disporum calcaratum is a rhizomatous woodland herb widespread from the Himalaya through southern China to mainland and insular Southeast Asia, with GBIF occurrences in China, Thailand, Myanmar, India, Nepal, Vietnam, Indonesia, Malaysia, Bhutan and Laos. It grows in the shaded understorey of moist broad-leaved and mixed forest, on humus-rich slopes and along stream banks, generally between 1,500 and 2,800 m. The photographed plant was recorded at Samathang in the Helambu region of Nepal at about 2,410 m in May, flowering during the moist pre-monsoon period typical of its mid-montane habitat.

The plant arises from a short, creeping rhizome and produces erect, branching stems bearing alternate, ovate to ovate-lanceolate leaves with prominent arcuate venation, rounded to cordate bases and acuminate tips. The flowers hang in terminal and axillary umbellate clusters; the six tepals are narrow, recurved and purple to violet, each outer tepal extended at the base into a short, conspicuous saccate spur that gives the species its epithet. There are six stamens with the typical Disporum arrangement, and a superior, three-locular ovary. The fruit is a globose, dark blue to black berry containing several seeds, dispersed by birds.

Disporum is now placed in the Colchicaceae rather than the older Liliaceae, and D. calcaratum is readily recognised among Asian congeners by its spurred, purple, pendent flowers. The species is widespread and ecologically a minor but characteristic element of the montane forest floor, important in shaded herb-layer communities. It is common across its broad range and is not regarded as threatened, though it depends on the persistence of intact, humid forest understorey.

Author: D.Don · Sources: POWO (Kew), GBIF, Flora of China Vol. 24 (Colchicaceae), Grierson & Long: Flora of Bhutan Vol. 3, Hara et al.: An Enumeration of the Flowering Plants of Nepal

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)

Anacardiaceae

Dobinea vulgaris

by G & P Jürgens

Buch.-Ham. ex D.Don

Bhutan2015 87
Bhutan Galephug 700m, October
Bhutan2015 86
Bhutan Galephug 700m, October
Bhutan2015 286
Bhutan Zhemgang 910m, October

Description

Dobinea vulgaris is a shrub or small subshrub of the eastern Himalaya and adjoining parts of southwestern China and northern Southeast Asia, recorded by GBIF from China, Nepal, India, Bhutan, Myanmar and Thailand across roughly 263 georeferenced occurrences. It is a plant of warm subtropical lower hill slopes, occupying open forest, scrub, rocky banks, ravines and disturbed roadside ground, generally at low to mid elevations. The Bhutanese records cited here, from Galephug at about 700 m and from Zhemgang at around 910 m, both in October, place it firmly in the low foothill zone of the southern Himalaya, where it flowers and fruits towards the close of the monsoon. It favours seasonally warm, humid conditions and is frequently found in secondary vegetation.

The plant has soft, somewhat herbaceous to weakly woody stems and opposite, simple leaves that are ovate to elliptic-lanceolate, acuminate, and conspicuously serrate or crenate-serrate along the margin, a foliage aspect unusual for the family. It is functionally dioecious: the small male flowers are borne in slender axillary or terminal panicles, while the female flowers are solitary or few and are remarkable for being adnate to an enlarged, persistent, leaf-like (foliaceous) bract that expands greatly in fruit and acts as a wing for wind dispersal. The fruit is a small compressed drupe-like structure carried on this accrescent membranous bract.

Dobinea is a small genus of only two species, and its placement within Anacardiaceae has historically been contentious; the herbaceous habit, opposite serrate leaves and unique bract-borne female flowers led some authors to segregate it (with Campylopetalum) into the family Podoaceae, although modern molecular phylogenetics confirms its position within an expanded Anacardiaceae, near the base of the family. This makes Dobinea vulgaris of particular interest to systematists studying the early diversification and morphological boundaries of the cashew family. The species is locally common within its range and is not regarded as of conservation concern.

Author: Buch.-Ham. ex D.Don · Sources: POWO (Kew), GBIF, Flora of China Vol. 11, Flora of Bhutan Vol. 2, Flora of Nepal, Flora of Pakistan, Pell et al.: systematics of the Anacardiaceae (including the Dobinea/Podoaceae problem)