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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.

Hypericaceae

Hypericum hookerianum

by G & P Jürgens

Wight & Arn.

Bhutan2014 8
Bhutan Sandrup 750m, May
Bhutan2014 222
Bhutan Karu-Chu 1800m, May

Description

Hypericum hookerianum is a Himalayan and Sino-Himalayan shrubby St John's wort, native across China, NE India, Nepal, Bhutan and Myanmar, with GBIF recording some 638 occurrences including numerous cultivated and naturalised records from Europe, North America and Australasia. In the wild it grows in forest margins, clearings, scrub and on open rocky slopes. The photographed Bhutanese plants from Sandrup (750 m) and Karu-Chu (1,800 m), both in May, illustrate its wide altitudinal tolerance from the subtropical foothills to the warm temperate belt.

It is an evergreen or semi-evergreen shrub with terete, often reddish branches. The leaves are opposite, ovate to oblong or lanceolate, sessile or nearly so, frequently glaucous beneath and dotted with pale translucent glands. The flowers are large and showy, borne singly or in few-flowered cymes; they are cup-shaped to bowl-shaped, deep golden-yellow, with five broad concave petals and a dense central boss of numerous stamens grouped in five fascicles surrounding a stout ovary with several styles. The fruit is a many-seeded septicidal capsule.

Hypericum hookerianum is a parent of several widely grown ornamental cultivars and hybrids, valued for its robust habit and bold flowers, which accounts for its scattered occurrence well beyond its native range. The translucent and dark glands of the foliage, characteristic of the genus, contain hypericin and hyperforin and related bioactive compounds. Within the large and complex genus Hypericum, the species belongs to the woody section Ascyreia, distinguished by its shrubby habit, large bowl-shaped flowers and fascicled stamens; it is of no conservation concern given its breadth of range and cultivation.

Author: Wight & Arn. · Sources: POWO (Kew), Flora of Bhutan Vol. 1, GBIF, Flora of China Vol. 13, Robson: Studies in the Genus Hypericum (Bulletin of the Natural History Museum)

Hypericaceae

Hypericum oblongifolium

by G & P Jürgens

Choisy

Garh 07 321JPG ergebnis
India Garhwal Maji 2650, June

Description

Hypericum oblongifolium is a shrubby St John's wort of the family Hypericaceae, native to the western and central Himalaya. GBIF records place it principally in India, Pakistan, Nepal and Afghanistan, with scattered records eastward to Bhutan and occurrences elsewhere representing cultivated plants. It grows on open, rocky hillsides, in scrub, along forest margins and on stream banks in the temperate zone, generally between about 1,500 and 3,000 m. The specimen illustrated from Maji in Garhwal, India, at around 2,650 m in June is typical of this sunny, well-drained mid-montane habitat where the shrub flowers in early summer.

The plant is a much-branched, evergreen to semi-evergreen shrub up to about 1–2 m, with reddish, arching, two-lined younger branches becoming terete with age. The leaves are opposite, sessile to subsessile, oblong to oblong-lanceolate, leathery, with translucent glandular dots, and somewhat glaucous beneath. The flowers are large and showy, golden-yellow, borne singly or in few-flowered terminal cymes; they have five spreading petals, numerous stamens grouped into bundles, and a superior ovary crowned by free styles, conforming to the characteristic Hypericum floral plan. The fruit is a septicidal capsule that splits to release numerous small seeds.

Within the large genus Hypericum the species belongs to the predominantly Asian section of woody, large-flowered shrubs and is closely allied to other Himalayan taxa such as H. hookerianum, from which it is separated by leaf shape, branch character and details of the styles. It is valued horticulturally for its abundant bright flowers and is used locally in folk medicine. Widespread and tolerant of disturbed, open ground, it is not considered threatened, and it readily colonises sunny banks and roadside scrub throughout the western Himalaya.

Author: Choisy · Sources: POWO (Kew), GBIF, Flora of Pakistan, Flora of Nepal, Flora of China Vol. 13, Robson: Studies in the genus Hypericum (Guttiferae)

Acanthaceae

Hypoestes triflora 

by GP Jürgens

(Forssk.) Roem. & Schult.

Nepal 99 997 ergebnis
West-Nepal Juphal 2600m, July

Description

Hypoestes triflora is a broadly distributed paleotropical herb ranging from tropical and southern Africa across the Arabian Peninsula to the Himalaya and southwestern China; its roughly 2040 GBIF records show a strong African centre in South Africa, Ethiopia, Tanzania, Kenya, Cameroon and the Congo basin, with Asian outliers in India, Nepal and China. In the western Himalaya it reaches the mid-montane zone, as in the collection near Juphal in West Nepal at about 2600 m in July, flowering during the monsoon. It grows in shaded, moist situations on forest floors and streambanks, as a soft-stemmed understorey herb of seasonally wet temperate and subtropical woodland.

The plant is an erect to straggling herb with four-angled, swollen-noded stems rooting at the lower joints. The opposite leaves are ovate to lanceolate, thin-textured and acuminate, with entire to obscurely toothed margins. The flowers are grouped in small axillary clusters, each subtended by bracts and typically containing three flowers, as the epithet records. The bilabiate corolla is pale pink to lilac or purplish, with a slender tube and deeply two-lipped limb. The fruit is an explosively dehiscent club-shaped capsule that ejects its seeds from retinacula-bearing placentae.

Within Acanthaceae, Hypoestes is allied to Justicia and recognised by its bracteate flower clusters and two-locular capsules; H. triflora is among the most wide-ranging species, its disjunct African-Asian distribution reflecting historical connections across the paleotropics. As a common woodland herb spanning many countries, it is of no particular conservation concern.

Author: (Forssk.) Roem. & Schult. · Sources: POWO (Kew), GBIF, Flora of China Vol. 19, Flora of Bhutan Vol. 2, Flora of Nepal, Flora of Tropical East Africa (Acanthaceae)

Hypoxidaceae

Hypoxis aurea

by GP Jürgens

Lour.

Nepal 97 491 P962
Nepal Num 1650m May
Nepal 99 198 ergebnis
West-Nepal Lara-Lake 2900m, June

Description

Hypoxis aurea Lour. is a small cormous geophyte of the Hypoxidaceae with a wide Asian and Pacific distribution, recorded from India, Nepal, Bhutan, Sri Lanka and China through Taiwan, Japan and Korea, across Southeast Asia (Myanmar, Thailand, Vietnam, Laos, Cambodia, Indonesia, the Philippines) to New Guinea, with around 1,240 georeferenced occurrences. It grows in open, well-lit grassy habitats: hill grassland, open pine and oak woodland, pasture, terrace banks and disturbed slopes, often in seasonally moist soils. The photographed plants from Num at about 1,650 m and from the Lara-Lake area of West Nepal at about 2,900 m, flowering in May and June, show its broad altitudinal span from subtropical foothills to the lower-temperate zone in the Himalaya.

It is a perennial herb arising from a small ovoid to tuberous corm. The leaves are all basal, several, narrowly linear and grass-like, often keeled and clothed (especially toward the base) in long soft hairs. The flowers are borne singly or few together on slender scapes shorter than or about equalling the leaves; each has six spreading yellow tepals, golden within and frequently greenish and hairy on the outer surface, with six stamens and an inferior, hairy ovary. The fruit is a small capsule opening to release numerous tiny black, often muricate seeds.

Hypoxis is a chiefly tropical and warm-temperate genus of grassland geophytes, and its members are well adapted to fire and seasonal drought through the perennating corm, which resprouts after burning or dry-season dormancy. The yellow, pollen-rich, nectarless flowers attract pollen-gathering insects. Widely distributed and frequently associated with grazed and disturbed grassland, H. aurea is common across its range and not considered threatened.

Author: Lour. · Sources: POWO (Kew), Flora of China Vol. 24, Flora of Bhutan Vol. 3, GBIF, Nordal: Hypoxidaceae (in Kubitzki, 1998)

Aquifoliaceae

Ilex dipyrena

by GP Jürgens

Wall.

Bh2008 420 P656
Bhutan Phobjika, 3100m April

Description

Ilex dipyrena, the Himalayan holly, is an evergreen tree or large shrub distributed along the Himalaya from Pakistan and northern India through Nepal, Sikkim and Bhutan into southern China (Yunnan, Xizang) and Myanmar. It is a characteristic constituent of cool temperate broad-leaved and mixed conifer forest, growing on shaded slopes, ridges and forest margins. It occurs mainly between about 1,800 and 3,300 m; the plant recorded in the Phobjikha valley of Bhutan at 3,100 m in April lies in the upper part of this band, within the moist temperate forest belt where it forms part of the evergreen understorey.

The plant is a small to medium-sized tree with greyish bark and glabrous twigs. The leaves are alternate, leathery and glossy dark green, elliptic to oblong-lanceolate, with a spinose-dentate margin bearing rigid marginal teeth on vigorous shoots, the teeth often reduced on older growth. The plant is dioecious, with small greenish-white, four-merous flowers clustered in the leaf axils. The fruit is a globose drupe ripening dull red, containing typically two pyrenes, a feature reflected in the epithet dipyrena, distinguishing it from the four- to five-seeded common holly.

Ilex is a large, near-cosmopolitan genus and the sole member of its family. Ilex dipyrena, described by Wallich, is the principal native holly of the Himalaya and a long-cultivated ornamental and parent of garden hybrids. Its evergreen, drupe-bearing habit provides food for birds, which disperse the seeds, and it contributes to the structure of temperate Himalayan forest. The species is widespread and common, and is not considered to be of conservation concern.

Author: Wall. · Sources: POWO (Kew), Flora of China Vol. 11, Flora of Bhutan Vol. 2, GBIF, Loizeau et al.: Ilex phylogeny

Aquifoliaceae

Ilex excelsa var. hypotricha

by G & P Jürgens

(Loes.) S.Y. Hu

Bhutan2015 536
Bhutan Mo-Chu 1300m, October
Bhutan2015 540
Bhutan Mo-Chu 1300m, October

Description

Ilex excelsa var. hypotricha is a holly of the eastern Himalaya and adjacent China, distributed through Bhutan, Nepal, NE India, Bangladesh and SW China as recorded by GBIF (CN, IN, NP, BD) on the basis of about 39 occurrences. The photographed tree was found in western Bhutan along the Mo-Chu at about 1,300 m in October. It is a component of subtropical and warm-temperate broadleaf forest, growing on humid hill slopes, along streams and forest margins, generally between about 1,000 and 2,200 m, where it occurs as an understorey to mid-canopy evergreen tree in mixed laurophyllous woodland.

It is an evergreen tree or large shrub with smooth grey bark and glabrous to finely puberulent young shoots. The leaves are alternate, leathery, elliptic to oblong-lanceolate, with an entire to remotely crenulate margin and an acuminate apex; this variety is distinguished by a thin pubescence on the lower surface, particularly along the midrib, the feature signalled by the epithet hypotricha. As in all Ilex the plants are dioecious, the small four-merous white to greenish flowers borne in axillary fascicles or short cymes, the staminate and pistillate flowers on separate trees. The fruit is a small globose red drupe containing several hard pyrenes (stones), characteristically ornamented as is diagnostic in the genus.

The genus Ilex is large and taxonomically intricate, with infraspecific variation in leaf indumentum often used to delimit varieties such as this one; the bony pyrene sculpturing remains an important systematic character. As a forest tree of moderately wide range, this taxon is not regarded as threatened, though its dependence on intact mid-elevation broadleaf forest links its fortunes to the conservation of eastern Himalayan woodland.

Author: (Loes.) S.Y. Hu · Sources: POWO (Kew), Flora of China Vol. 11, Flora of Bhutan Vol. 2, GBIF, Loesener: Monographia Aquifoliacearum

Schisandraceae

Illicium griffithii

by G & P Jürgens

Hook.f. & Thomson

Bhutan2012 346
Bhutan Dochu-La 3000m, September

Description

Illicium griffithii Hook.f. & Thomson is an aromatic evergreen tree or shrub of the eastern Himalaya and montane Southeast Asia. GBIF records it from Bhutan, NE India, China, Myanmar, Bangladesh, Vietnam, Cambodia and Malaysia (about 220 occurrences), a distribution centred on the wet temperate to subtropical forests of the eastern Sino-Himalaya. It grows in cool, humid, mossy broad-leaved and mixed conifer forest, often as an understorey component on damp slopes and ridges, typically between roughly 1,800 and 3,000 m; the illustrated plant is from Bhutan at Dochu-La, 3,000 m, in September, near the upper limit of its range.

The plant is a small to medium-sized tree with smooth bark and aromatic tissues. The leaves are alternate but crowded toward the branch tips in pseudowhorls, simple, entire, elliptic to oblanceolate, leathery, glabrous and gland-dotted, exuding an anise-like scent when crushed. The flowers are solitary and axillary, with numerous spirally arranged perianth segments grading from sepaloid to petaloid, pinkish to dark red, the stamens and free carpels also numerous in the manner of the basal angiosperms. The fruit is the characteristic star-shaped aggregate of (usually) 8–13 woody follicles arranged in a single whorl, each follicle opening to release a single glossy seed.

Illicium (Schisandraceae, formerly Illiciaceae) belongs to the basal angiosperm order Austrobaileyales. Like its relatives the seeds and fruit contain toxic sesquiterpene lactones (anisatin-type), and the star anise of this species is harvested locally for incense, flavouring and medicine, demanding care given its toxicity. The species is widespread within suitable montane forest and is not currently regarded as threatened.

Author: Hook.f. & Thomson · Sources: POWO (Kew), GBIF, Flora of China Vol. 7, Flora of Bhutan Vol. 1, Smith: A Taxonomic Review of Illicium (Sargentia)

Balsaminaceae

Impatiens arguta

by G & P Jürgens

Hook.f. & Thomson

Bhutan2012 329
Bhutan Dochu-La 3200m, September
Bhutan2012 330
Bhutan Dochu-La 3200m, September

Description

Impatiens arguta is a Sino-Himalayan balsam distributed from the central and eastern Himalaya through Myanmar into south-western China; GBIF records around 934 occurrences across China, India, Myanmar, Bhutan and Nepal. It is a plant of cool, humid temperate forest, growing on shaded moist banks, stream sides, forest margins and clearings, often in the broadleaved and mixed conifer belt. The image from Dochu-La in Bhutan at about 3200 m in September shows it flowering at a misty high pass late in the monsoon season, when temperate balsams reach their flowering peak in the abundant moisture and dappled shade of these slopes.

It is an erect, succulent perennial herb with stout, translucent, glabrous stems swollen at the nodes. The leaves are alternate or subopposite, ovate to lanceolate, with a sharply toothed (arguta, sharp-toothed) margin, an acuminate apex and a petiole sometimes bearing small glands. Flowers are borne singly or few together in the leaf axils on slender pedicels, zygomorphic and showy, typically purple to violet or pinkish; the lower sepal is boat-shaped and prolonged into a slender incurved spur, and the lateral united petals are two-lobed. The fruit is a fleshy, club-shaped capsule that dehisces explosively, scattering the seeds by elastic recoil of the valves.

The genus Impatiens is exceptionally species-rich and rapidly diversifying in the Himalaya, where many narrowly endemic taxa replace one another along altitudinal and longitudinal gradients. The explosive ballistic seed dispersal and nectar-spurred, insect-pollinated flowers of I. arguta are characteristic of the family. The species is widespread and not of conservation concern, but as a moisture-demanding forest herb it depends on the intact humid temperate woodlands of the eastern Himalaya.

Author: Hook.f. & Thomson · Sources: POWO (Kew), GBIF, Flora of Bhutan, Flora of China (Balsaminaceae), Grey-Wilson monograph of Impatiens

Balsaminaceae

Impatiens cymbifera

by GP Jürgens

Hook.f.

Nepal 95 205 P344 ergebnis
Nepal Cluning-Khola 2900m October

Description

Impatiens cymbifera Hook.f. is a Sino-Himalayan balsam distributed across Nepal, China, India, Bhutan and Myanmar (NP, CN, IN, BT, MM), with GBIF recording about 103 occurrences. It is a plant of cool, humid montane forest, favouring shaded streamsides, seepage slopes, moist rock faces and path margins. The material photographed at the Cluning-Khola in Nepal at 2900 m in October reflects its autumn flowering in the temperate forest belt, where late-monsoon moisture sustains its succulent growth and prolongs anthesis into the post-monsoon season.

It is an erect, succulent annual with translucent, often reddish, watery stems swollen at the nodes and rooting below. The leaves are alternate, ovate to elliptic with a serrate margin bearing small stipitate glands at the base, and an acuminate apex. The flowers are borne singly or few in the leaf axils on slender pedicels, the corolla zygomorphic; the lower sepal is conspicuously enlarged into a boat-shaped (cymbiform, hence the epithet) saccate body abruptly contracted into an incurved spur, while the lateral united petals form two-lobed wings. The capsule is the characteristic clavate, explosively dehiscent fruit of the genus, scattering seeds by elastic recoil of the valves.

Within the large and intricate genus Impatiens, a centre of diversity in the Sino-Himalayan region, I. cymbifera belongs to the forest-dwelling annuals with strongly saccate lower sepals. Its flowers are pollinated by long-tongued insects, and explosive ballistic seed dispersal aids colonisation of moist disturbed ground. As a moisture-demanding annual it is tied to intact montane forest hydrology, and such balsams indicate undisturbed humid forest.

Author: Hook.f. · Sources: POWO (Kew), GBIF, Flora of Nepal, Flora of China Vol. 12, Flora of Bhutan Vol. 2, Grey-Wilson monograph and Sino-Himalayan Impatiens studies

Balsaminaceae

Impatiens discolor

by GP Jürgens

DC.

Bh09 286 P469
Bhutan Tongtsa 2100m, June

Description

Impatiens discolor is an annual herb of the eastern Himalaya and adjoining ranges, documented by GBIF from Nepal, India, Bhutan, China, Thailand and Papua New Guinea across roughly 78 occurrences, several records being indeterminate as to country. It favours shaded, humid montane forest, growing along stream banks, in moist gullies and on seepage-fed roadside banks within evergreen and mixed broad-leaved woodland, typically at middle elevations. The photographed plant from Tongsa (Trongsa) in central Bhutan at about 2100 m, flowering in June with the onset of the monsoon, is typical of the warm, wet conditions that the genus exploits during the rainy season.

The plant has a succulent, translucent, often reddish stem that is erect or ascending and watery in texture, with swollen nodes. The leaves are alternate, ovate to elliptic, with a serrate or crenate-serrate margin and an acuminate apex, frequently glaucous or paler beneath, giving the discolorous appearance referenced by the epithet. The zygomorphic flowers are borne singly or in few-flowered axillary clusters; the lower sepal forms a saccate spur, and the showy yellow corolla (sometimes spotted) is built from a standard and two lateral united petals. The fruit is a fleshy, club-shaped capsule that dehisces explosively, the valves coiling abruptly to fling the seeds well away from the parent.

Balsaminaceae are notoriously taxonomically difficult, with Impatiens hyper-diverse and richly speciose in the Sino-Himalaya, where rapid radiation has produced many narrowly distributed, ecologically specialised taxa. Explosive seed dispersal and dependence on insect pollinators, together with a strictly annual life cycle, tie the species closely to seasonal monsoon moisture. While not formally assessed as threatened, the group's fine-scale habitat specificity makes individual populations sensitive to forest disturbance and altered rainfall regimes.

Author: DC. · Sources: POWO (Kew), GBIF, Flora of China, Flora of Bhutan, Annotated Checklist of the Flowering Plants of Nepal, Grey-Wilson "Impatiens of Africa" and Sino-Himalayan Impatiens monographic studies