Tag:

Autumn

Orchideaceae

Dendrobium hookerianum

by GP Jürgens

Lindl.

Bhutan2012 439
Bhutan Wangdi 2500m, September
Bhutan2012 1256
Bhutan Trashigang 2000m, October
Bhutan2012 1257
Bhutan Trashigang 2000m, October

Description

Dendrobium hookerianum, Hooker's dendrobium, is an eastern Himalayan epiphytic orchid known from China, India, Bhutan, Myanmar and Nepal, with 127 GBIF occurrences concentrated in the moist mid-montane forests of the region. It grows on tree trunks and branches in humid temperate broadleaved and conifer forest, broadly between about 1500 and 2500 m. The illustrated plants were recorded in Bhutan at Wangdi (Wangdue) at 2500 m in September and at Trashigang at 2000 m in October, autumn-flowering populations in mist-laden forest where cool nights and high humidity prevail.

The species forms long, pendent or arching, slender stems clothed in tubular sheaths and bearing many distichous, lanceolate, thin-textured leaves. From the upper nodes arise lateral racemes carrying several large, golden-yellow flowers. The spreading, elliptic sepals and broader petals are clear yellow, and the broad, suborbicular, fringed labellum is conspicuously marked with two deep maroon to blackish blotches on the disc and edged with a dense marginal fringe. The mentum is short, the column with a prominent foot, and the pollinia waxy.

Named in honour of Sir Joseph Dalton Hooker, the species belongs to Dendrobium section Dendrobium and is prized among Himalayan orchids for its showy fringed lip. Its restricted eastern Himalayan range, autumn flowering and ornamental appeal make it a target for collectors, and combined with ongoing forest clearance this renders wild populations vulnerable. International trade in the genus is regulated under CITES Appendix II.

Author: Lindl. · Sources: POWO (Kew), GBIF, Flora of Bhutan, Flora of China, Orchids of Bhutan, Dendrobium and its Relatives (Lavarack et al.)

Orchideaceae

Dendrobium longicornu

by GP Jürgens

Lindl.

Bhutan2015 453
Bhutan Trontsa 2300m, October
Bhutan2012 441
Bhutan Wangdi 2600m, September
Bhutan2012 1331
Bhutan Pemagatse 2600m, September

Description

Dendrobium longicornu is an epiphytic orchid widespread across the eastern Himalaya and Indo-Burmese region, with GBIF recording over 300 occurrences and native range spanning India, China, Nepal, Bhutan, Vietnam, Myanmar, Bangladesh and Thailand, besides cultivated records in Europe. It grows as an epiphyte on mossy trunks and branches in humid, temperate to subtropical broad-leaved forest, typically between about 1500 and 2700 m. Bhutanese material was photographed at Trontsa (2300 m), Wangdi and Pemagatse (both 2600 m) in September and October, flowering on shaded, moss-laden trees in cool montane woodland.

The plant forms tufted, slender, erect to pendulous stems clothed in black-hairy leaf sheaths, bearing thin, lanceolate leaves toward the apex. The flowers, borne singly or few together near the stem tips, are showy and predominantly white with a fringed labellum marked by orange to greenish veining in the throat. The narrow tepals are spreading; the diagnostic feature is the long, slender, horn-like spur (mentum) formed by the lateral sepals and column foot, from which the epithet "longicornu" derives. The column is short, the anther cap bearing waxy pollinia, and the fruit a ribbed capsule.

Within the large genus Dendrobium, this species belongs to the white-flowered Formosae (nigrohirsute) section, distinguished by the dark hairs on stems and sheaths. Although widespread, it is sought by orchid collectors and is affected by habitat loss and overharvesting; like all Dendrobium it is listed on CITES Appendix II, regulating international trade.

Author: Lindl. · Sources: POWO (Kew), GBIF, Flora of Bhutan, Flora of China, The Orchids of Bhutan (Pearce & Cribb), CITES Appendix II listing

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)

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

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)

Asteraceae

Dolomiaea macrocephala 

by G & P Jürgens

DC. ex Royle

Garw 2005 147 ergebnis ergebnis
India Garhwal Kuari-Pass 3700m, September
Garw 2005 308 ergebnis ergebnis
India Garhwal Kuari-Pass 3700m, September

Description

Dolomiaea macrocephala is a stemless alpine thistle-relative of the western and central Himalaya and adjacent Central Asian highlands, recorded from India, Nepal, Pakistan, China, Iran and Mongolia, with about 131 occurrences in GBIF. It grows on open alpine slopes, stony pastures and grazed meadows of the upper subalpine and alpine zones, generally between 3000 and 4500 m, often in well-drained turf exposed to full sun. The photograph from the Kuari Pass in Garhwal, India, at about 3700 m in September shows the plant in fruit late in the alpine season among the short turf of the high-meadow belt.

The species is a perennial, essentially acaulescent herb arising from a stout taproot and a short rootstock. The leaves form a flat or appressed basal rosette and are pinnatifid to lyrate with spiny-toothed margins, green above and frequently white-tomentose beneath. As the specific epithet indicates, the conspicuously large flower heads are sessile or nearly so, sitting in the centre of the rosette; the involucre bears numerous imbricate, often spine-tipped phyllaries surrounding a head of purple, tubular disc florets. The achenes are oblong and crowned by a pappus of plumose or barbellate bristles aiding wind dispersal.

The genus Dolomiaea was long included within Jurinea and Saussurea and belongs to the thistle tribe Cardueae of the Asteraceae; molecular studies support its recognition as a distinct Sino-Himalayan and Central Asian lineage. The ground-hugging rosette and centrally clustered heads represent a typical adaptation to wind exposure and heavy grazing at high elevation. Several species, including this one, have a history of use in Tibetan and Himalayan herbal medicine. Widespread across its montane range, D. macrocephala is not regarded as threatened.

Author: DC. ex Royle · Sources: POWO (Kew), GBIF, Flora of China, Flora of Pakistan, Annotated Checklist of the Flowering Plants of Nepal, Susanna and Garcia-Jacas revisions of the Cardueae

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

Asteraceae

Duhaldea eupatorioides

by G & P Jürgens

(DC.) Anderb.

Bhutan2012 1356
Bhutan Sandrup 1500m, October

Description

Duhaldea eupatorioides is a subtropical to warm-temperate composite of the Himalaya and adjacent montane Asia, recorded from India, China, Nepal, Bhutan, Thailand, Myanmar, Bangladesh, Pakistan, Laos and Vietnam, with GBIF listing about 156 occurrences. It grows on open hillsides, forest margins, scrub, roadcuts and grassy slopes in the foothill and lower montane belt, broadly from 1000 to 2500 m. The photographed plant was found in Bhutan at Sandrup at 1500 m in October, when the species comes into bloom at the close of the monsoon, its leafy stems carrying numerous small heads above the autumn grassland.

It is an erect, somewhat woody-based perennial herb or subshrub with leafy, branching, often pubescent stems. The leaves are alternate, ovate-lanceolate to elliptic, acuminate, with serrate margins and a finely hairy surface, narrowing to a short petiole or sessile base, the foliage recalling Eupatorium, hence the epithet. The capitula are small, numerous, and aggregated into terminal corymbose panicles; each head is radiate, with an involucre of several rows of imbricate bracts, marginal yellow ray florets and yellow tubular disc florets. The fruit is a ribbed, hairy cypsela crowned by a pappus of barbellate bristles, dispersed by wind.

The species belongs to the tribe Inuleae and to genus Duhaldea, a segregate split from the broadly defined Inula on molecular and morphological grounds; older floras may list it under Inula eupatorioides. A tolerant species of open and disturbed montane habitats, it is widespread and not of conservation concern. Its Sino-Himalayan to Indochinese range typifies the warm-temperate element of the southern Asian mountain arc.

Author: (DC.) Anderb. · Sources: POWO (Kew), GBIF, Flora of China, Flora of Bhutan, Flora of Nepal, generic revision of Inuleae (Anderberg)