Tag:

Autumn

Begoniaceae

Begonia annulata

by GP Jürgens

K.Koch

Bhutan2015 146
Bhutan Galephug 700m, October

Description

Begonia annulata is a Himalayan and Indo-Burmese begonia ranging through India, Bhutan, Bangladesh, Nepal and Myanmar; GBIF lists about 109 occurrences, the lower figure reflecting its restriction to humid lowland and submontane forest. It grows in warm, shaded, perpetually moist habitats, on damp rocks, mossy banks, ravines and forest-floor seepages in evergreen broadleaved forest of the foothills and outer ranges. The photograph from Galephug in southern Bhutan at about 700 m in October shows it in the low, humid subtropical belt along the Himalayan front, fruiting late in the year where high rainfall and dense canopy sustain its succulent growth.

It is a fleshy perennial herb with an erect to ascending, jointed, translucent stem arising from a creeping rhizome or tuberous base. The leaves are alternate, conspicuously asymmetric (oblique) at the base as is typical of the genus, ovate to broadly ovate with an acuminate apex and toothed margin, palmately veined and often bearing scattered hairs, the petioles and nodes sometimes ringed (annulate, the source of the epithet). Plants are monoecious, the flowers white to pale pink and unisexual, borne in axillary cymes; staminate flowers with several stamens and pistillate flowers with a conspicuously winged inferior ovary. The fruit is a three-winged, unequally winged capsule containing very numerous minute seeds.

Begonia is one of the largest angiosperm genera, strongly radiated in the wet forests of tropical Asia, and B. annulata represents the shade- and moisture-demanding rhizomatous group of the eastern Himalaya. Its asymmetric leaves, winged capsules and dust-fine seeds are hallmarks of the family. While not formally assessed as threatened, such narrowly humid-forest specialists are sensitive to lowland deforestation and habitat drying along the Himalayan foothills.

Author: K.Koch · Sources: POWO (Kew), GBIF, Flora of Bhutan, Flora of British India (Hooker), Tebbitt Begonias: Cultivation, Identification and Natural History

Begoniaceae

Begonia dioica

by GP Jürgens

Buch.-Ham. ex D.Don

Bhutan2012 472
Bhutan Wangdi 2500m, September

Description

Begonia dioica is a Himalayan tuberous herb whose GBIF range (c. 147 occurrences) centres on India, Nepal, Bhutan and Pakistan, with a few cultivated European records. It grows in shaded, humid situations—mossy rock faces, damp banks, ravine walls and broadleaved forest floor—generally at mid elevations between roughly 1000 and 2800 m, flowering through the monsoon into autumn. The plant photographed from Wangdi (Wangdue) in Bhutan at 2500 m, in flower in September, typifies its preference for cool, moist, partially shaded montane microhabitats kept continuously damp by seepage.

It is a low, succulent, monoecious perennial arising from a small subterranean tuber, with reddish, watery, more or less hairy stems 10–40 cm tall. The leaves are alternate, ovate and markedly asymmetric (oblique) at the base in the manner characteristic of the genus, palmately veined, with a serrate to shallowly lobed, ciliate margin. As in all Begonia the flowers are unisexual and borne in axillary cymes; staminate flowers have two larger and two smaller white to pinkish tepals with yellow stamens, while pistillate flowers subtend an inferior, three-winged ovary. The fruit is a membranous, unequally three-winged capsule releasing minute seeds.

Described by Buchanan-Hamilton (ex D. Don), the epithet "dioica" is misleading because the species is in fact monoecious—a frequent source of nomenclatural confusion in Begonia, a genus of several thousand species. It is locally frequent and not regarded as threatened, though dependent on intact shaded forest and seepage. Ecologically it specialises in moist rock and forest-floor niches, its dust-like seeds dispersed by water splash and air currents.

Author: Buch.-Ham. ex D.Don · Sources: POWO (Kew), GBIF, Flora of Bhutan, Flora of British India, Begoniaceae (Doorenbos, Sosef & de Wilde monograph)

Begoniaceae

Begonia josephi

by GP Jürgens

A.DC.

Bhutan2012 487
Bhutan Pele-La 2850m, September

Description

Begonia josephi is a Himalayan herb distributed through India, Nepal, Bhutan, southern China, Myanmar and Bangladesh, with 177 GBIF occurrences across the region. It is a plant of cool, humid, shaded montane habitats — mossy rock faces, banks, ravines and the floor of broadleaved and mixed forest — in the temperate zone, generally between about 2000 and 3200 m, a higher and cooler niche than many of its lowland congeners. The illustrated plant from the Pele-La in central Bhutan at around 2850 m, in September at the end of the monsoon, is characteristic of its preference for moist, montane forest reaching its flowering peak late in the wet season.

It is a tuberous perennial herb arising from a depressed underground tuber, with one or few erect, succulent, often reddish stems. The leaves are alternate and conspicuously asymmetric (oblique-based) as in the genus, broadly ovate to suborbicular, palmately veined, irregularly toothed and frequently bronze- or red-tinged, sometimes with a paler zone. The monoecious, zygomorphic flowers are pink to rose and arranged in axillary cymes; staminate flowers bear a cluster of stamens while pistillate flowers carry an inferior, unequally 3-winged ovary. The fruit is the typical winged, dehiscent capsule releasing copious minute seeds.

Belonging to the tuberous Himalayan begonias of section Platycentrum and allied groups, B. josephi shows the strongly seasonal phenology of monsoon-climate species, dying back to its tuber through the dry winter and re-emerging with the rains. The genus Begonia is hyperdiverse and the Eastern Himalaya a significant centre of endemism; like other shade-demanding forest begonias the species depends on intact humid forest cover, leaving it locally vulnerable to deforestation despite a fairly wide overall range.

Author: A.DC. · Sources: POWO (Kew), GBIF, Flora of Bhutan, Flora of British India, Annotated Checklist of the Flowering Plants of Nepal, Begoniaceae monographic studies

Begoniaceae

Begonia megaptera

by G & P Jürgens

A.DC.

Bhutan2012 480 ergebnis
Bhutan, Wangdi 1800m, September
Bhutan2012 481
Bhutan, Wangdi 1800m, September

Description

Begonia megaptera is a tuberous begonia native to the eastern Himalaya and adjacent regions, recorded from Nepal, northeast India (Sikkim, Darjeeling, Meghalaya), Bhutan, and Myanmar, with occasional records from Sri Lanka. It inhabits moist, shaded environments including rock crevices, mossy banks, stream margins, and damp earth walls in warm broadleaved and subtropical forests at elevations of 900–2,500 m. The species has been documented near Wangdi in Bhutan at 1,800 m, where it flowers during the monsoon and post-monsoon period in September.
The plant is a perennial herb arising from a globose tuber, with erect or ascending, succulent, sparsely branched stems 20–50 cm tall, tinged red and bearing scattered hairs. Leaves are alternate, broadly ovate to suborbicular, distinctly asymmetric, 8–20 cm long and nearly as wide, with a cordate base, irregularly serrate to dentate margins, and palmately veined undersurface often flushed reddish-purple. Stipules are large, ovate, and persistent. The inflorescence is a dichasial cyme bearing both male and female flowers; male flowers have two large, broadly ovate, white to pale pink tepals and numerous yellow stamens, while female flowers have five unequal tepals and a prominently three-winged inferior ovary — the epithet "megaptera" (large-winged) refers to the conspicuously enlarged wing on the fruit. The capsule is pendulous, with one wing much larger than the other two, up to 3 cm broad.
Begonia megaptera belongs to Begonia section Platycentrum and is distinguished by its notably large, unequal capsule wings and broad, nearly orbicular leaves. With only 63 occurrence records in GBIF, it remains a rather uncommon species. Begonia is one of the largest angiosperm genera, with over 2,000 species, and the eastern Himalayan region represents a secondary centre of diversity. B. megaptera contributes to the rich lithophytic and epipetric flora characteristic of humid gorge habitats in the region.

Author: A.DC. · Sources: POWO (Kew), GBIF, Flora of Bhutan Vol. 2, Doorenbos et al.: The Sections of Begonia (1998), Hughes et al.: Asian Begonia (2015)

Begoniaceae

Begonia nepalensis

by GP Jürgens

Warb.

Bhutan2015 123
Bhutan Galephug 600m, October
Bhutan2015 126
Bhutan Galephug 600m, October

Description

Begonia nepalensis is a robust herbaceous Begonia of the Himalaya and its foothills, recorded by GBIF from Nepal, India, Bhutan, China and elsewhere across about 91 occurrences. It grows in warm, humid, shaded habitats, on moist banks, in ravines, beside streams and on damp rocks within subtropical and lower montane broad-leaved forest, typically at low to middle elevations. The plant photographed at Gelephu (Galephug) in southern Bhutan at about 600 m, in October, reflects this warm, wet foothill setting where the species flourishes in the deep shade and high humidity of the monsoon-fed forest understorey.

The plant is a tall, succulent, erect herb arising from a thick rhizome, with stout, somewhat fleshy, swollen-noded stems. The leaves are alternate, large and markedly asymmetric (oblique) at the base as is characteristic of the genus, broadly ovate, acuminate, with a toothed to shallowly lobed and ciliate margin and palmate venation; the foliage is often somewhat hairy. The plant is monoecious, bearing separate male and female flowers in the same axillary cymes; the white to pinkish flowers have tepals rather than differentiated sepals and petals, the staminate flowers with a cluster of stamens and the pistillate with an inferior, conspicuously winged ovary. The fruit is a three-winged, unequally winged capsule that dries and releases very numerous minute seeds.

Begonia is one of the largest angiosperm genera, hyper-diverse in the wet tropics, and the Himalayan species such as B. nepalensis belong to the assemblage of large-leaved, cane-stemmed forest herbs adapted to shaded, perennially moist habitats. The asymmetric leaves, winged capsules and dust-like seeds are hallmarks of the family. Although not assessed as threatened, the species' dependence on humid, undisturbed forest understorey makes it sensitive to deforestation and drying, and its restriction to the warm Himalayan foothills reflects a tropical-Asian biogeographic affinity.

Author: Warb. · Sources: POWO (Kew), GBIF, Flora of China, Flora of Bhutan, Annotated Checklist of the Flowering Plants of Nepal, Tebbitt "Begonias: Cultivation, Identification, and Natural History"

Begoniaceae

Begonia ovatifolia

by GP Jürgens

A.DC.

Bhutan2015 229
Bhutan Zhemgang 950m, October
Bhutan2015 226
Bhutan Zhemgang 950m, October

Description

Begonia ovatifolia A.DC. is an eastern Himalayan herb known from Bhutan, north-eastern India and Nepal, a comparatively narrow-ranging species with few records (GBIF lists about 58 occurrences). It is a plant of shaded, humid situations – moss-covered rock faces, stream banks, damp ravines and the floor of evergreen broad-leaved forest – at low to mid elevations. The illustrated material was collected at Zhemgang in central Bhutan at about 950 m in October, where the monsoon-fed forests provide the perennially moist, sheltered microhabitat that suits the genus.

It is a perennial herb with succulent, often reddish-tinged stems arising from a fibrous-rooted or shortly rhizomatous base. The leaves are alternate, asymmetric (oblique) at the base as is typical of Begonia, ovate in outline with an acuminate apex and a finely serrate to denticulate margin, the lamina sometimes sparsely hairy. The plants are monoecious, bearing unisexual flowers in axillary cymes; the staminate flowers have showy tepals and a cluster of yellow stamens, the pistillate flowers an inferior, conspicuously 3-winged ovary with branched stigmas. The fruit is a winged capsule, one wing usually larger, dehiscing to release very numerous minute seeds.

Begonia (Begoniaceae) is one of the largest angiosperm genera, with the Sino-Himalayan species forming a centre of diversity and high local endemism. B. ovatifolia belongs to this assemblage of forest-floor herbs whose narrow distributions make them sensitive to habitat loss and forest disturbance, though the species is not formally assessed. Its inferior winged ovary and dust-like seeds are characteristic adaptations for dispersal in the humid, low-light understorey it occupies.

Author: A.DC. · Sources: POWO (Kew), GBIF, Flora of Bhutan, Flora of China, Begonia treatment in Flora of British India, Tebbitt studies of Asian Begonia, Camfield & Hughes phylogeny of Begonia

Begoniaceae

Begonia rubella

by GP Jürgens

Buch.-Ham. ex D.Don

Bhutan2015 228 ergebnis
Bhutan Zhemgang 910m, October

Description

Begonia rubella is a Himalayan herb ranging through Nepal, northern India and Bhutan, with scattered GBIF records (67 occurrences) extending the data to Papua New Guinea, which most likely represents misidentification rather than a genuine disjunction. It is a plant of shaded, humid microhabitats — moist rock faces, stream banks, damp ravines and the floor of broadleaved subtropical to lower-temperate forest — where constant atmospheric moisture and deep shade prevail. The illustrated plant from Zhemgang in central Bhutan at about 910 m, in October at the close of the monsoon, exemplifies its preference for warm, wet, low-montane valleys.

The species is a soft, succulent perennial herb arising from a tuberous or rhizomatous rootstock, with erect to ascending, somewhat fleshy, reddish-tinged stems (the epithet rubella alluding to this colouring). The leaves are alternate, markedly asymmetric (oblique) at the base as is typical of the genus, ovate to broadly ovate, acuminate, irregularly toothed and often flushed red beneath. The flowers are monoecious and zygomorphic, pink to rose, borne in axillary cymes; staminate flowers bear numerous stamens, pistillate flowers an inferior, conspicuously 3-winged ovary. The fruit is the characteristic unequally 3-winged dehiscent capsule shedding minute seeds.

Begonia, the sole large genus of Begoniaceae, is one of the most species-rich angiosperm genera, and the Sino-Himalayan region is a notable centre of diversity. B. rubella belongs to the assemblage of tuberous Himalayan begonias adapted to a strongly seasonal monsoon climate, dying back in the dry winter. Like many narrowly distributed forest begonias it depends on undisturbed humid shade, making it sensitive to forest clearance, though horticultural interest in the group has aided its documentation.

Author: Buch.-Ham. ex D.Don · Sources: POWO (Kew), GBIF, Flora of Bhutan, Flora of British India, Annotated Checklist of the Flowering Plants of Nepal, Begonian Resource (Begoniaceae monographic studies)

Begoniaceae

Begonia xanthina

by GP Jürgens

Hook.

Bhutan2015 132
Bhutan Galephug 600m, October
Bhutan2015 135
Bhutan Galephug 600m, October

Description

Begonia xanthina is a herbaceous perennial of the eastern Himalaya and adjacent Indo-Burma, recorded from northeastern India, Bhutan, Nepal, southern China and Myanmar, with cultivated occurrences in Belgium and the Netherlands; GBIF holds about 61 georeferenced records. It inhabits shaded, humid evergreen forest, growing on moist rocks, mossy banks, ravine sides and seepage slopes at low to mid elevations, favouring deep shade and the high humidity of monsoon forest. The photographed plant from Gelephu (Galephug) in southern Bhutan at 600 m in October is typical of these warm, wet subtropical foothill forests where it flowers in the post-monsoon season.

It is a rhizomatous, monoecious herb with a stout creeping rhizome and few large basal leaves. The leaves are broadly ovate, markedly asymmetric (oblique) at the base, cordate, often coloured deep green above with reddish or purplish tinting beneath and a long fleshy petiole. The inflorescence is an axillary cyme borne on an erect peduncle, carrying showy nodding flowers; the tepals are yellow, the staminate flowers with four tepals and numerous yellow stamens, the pistillate flowers with an inferior, three-winged ovary bearing unequal wings and twisted bifid stigmas. The fruit is a pendulous winged capsule dehiscing to release minute seeds.

Described by W.J. Hooker, Begonia xanthina is notable as one of the few yellow-flowered Asian begonias, placed in section Platycentrum, and has long been valued in horticulture for its handsome foliage and unusual flower colour. Its monoecious habit and reliance on small generalist insect pollinators are typical of the genus. Restricted to specialised forest microhabitats, it is sensitive to habitat loss, and conservation of intact foothill forest is important for its persistence.

Author: Hook. · Sources: POWO (Kew), GBIF, Flora of China Vol. 13, Flora of Bhutan Vol. 2, Flora of Nepal, Begonias of the Himalaya (Tebbitt)

Betulaceae

Betula utilis

by GP Jürgens

D.Don

Nepal 95 182 P303 ergebnis
Nepal North of Rupien La 3200 m October

Description

Betula utilis, the Himalayan birch, is the characteristic tree of the upper subalpine forest belt throughout the Himalaya and into western China, native across China, Nepal, India, Pakistan, Bhutan and Afghanistan; its roughly 6400 GBIF records combine wild Himalayan occurrences with cultivation in Britain, Germany, France and North America. It forms the treeline forests of the range, as recorded north of the Rupien La in Nepal at about 3200 m in October, typically between 3000 and 4000 m. There it forms pure stands or grows with rhododendron, fir and juniper on cool, moist north-facing slopes, marking the limit of arborescent vegetation.

The species is a deciduous tree, often gnarled near the treeline, with the famous smooth, papery, peeling bark ranging from white and pinkish to coppery or dark brown that exfoliates in horizontal sheets. The leaves are alternate, ovate, doubly serrate and acuminate, turning gold in autumn. As a wind-pollinated monoecious birch it bears separate male and female catkins; the pendulous male catkins shed pollen in spring, while the female catkins mature into cylindrical, disintegrating fruiting catkins releasing small, winged nutlets.

Betula utilis is taxonomically variable, divided into several subspecies and varieties differing in bark colour and leaf form, including the white-barked western populations grown horticulturally as var. jacquemontii. Ecologically it is a keystone of Himalayan treeline ecosystems, its bark long used as a writing material and in traditional medicine. As the treeline shifts under climatic warming and forests face grazing pressure, it is an important indicator species in studies of mountain ecosystem change.

Author: D.Don · Sources: POWO (Kew), GBIF, Flora of China Vol. 4, Flora of Bhutan Vol. 1, Flora of Nepal, Birches: The Genus Betula (Ashburner & McAllister)

Fabaceae

Biancaea decapetala

by GP Jürgens

(Roth) O.Deg.

Bhutan2012 401
Bhutan Wangdi 2700m, September

Description

Biancaea decapetala (formerly Caesalpinia decapetala), the Mysore thorn, is a vigorous scrambling shrub native to tropical and subtropical Asia but now widely naturalised across the tropics; its 9040 GBIF occurrences span China, India and much of Asia together with Africa, Australia, the Americas and Pacific islands, reflecting an extensive introduced range. In its native Himalayan setting it grows in thickets, forest margins, riverbanks, scrub and waste ground from the lowlands to about 2700 m. The collection figured, from Wangdi in Bhutan at 2700 m in September, represents the upper subtropical edge of its range, where it forms dense thorny tangles on warm, disturbed valley slopes.

It is a robust, scandent shrub or liana with long arching woody branches armed with numerous stout, recurved prickles and a rusty-brown indumentum on young growth. The leaves are large, alternate and bipinnate, with several pairs of pinnae each bearing many small oblong leaflets. The inflorescence is an erect, elongate terminal raceme of showy flowers; the corolla is bright yellow with five slightly unequal petals (the epithet alluding to ten perianth parts), and the ten free stamens have hairy, reddish filaments. The fruit is a flattened, woody, oblong pod, beaked at the apex and indehiscent or tardily splitting, containing several seeds.

The genus on the source page is given as Caesalpinia; molecular and morphological studies have segregated this species into Biancaea (Fabaceae, subfamily Caesalpinioideae), the combination accepted by POWO. Used regionally for impenetrable hedges and in traditional medicine, the species is an aggressive coloniser and a serious invasive weed in South Africa, Australia and elsewhere, smothering native vegetation; it is consequently a biosecurity and conservation concern well beyond its native Asian range.

Author: (Roth) O.Deg. · Sources: POWO (Kew), GBIF, Flora of China, Flora of Bhutan, Legumes of the World (Caesalpinioideae)