By Seamus O’Brien.

The sun was setting as we travelled across the tropical plains of West Bengal and made our initial ascent of the Himalayan foothills towards the former British hill station of Darjeeling. The aim of our expedition was to retrace the footsteps of the famous British botanist and explorer, Joseph Dalton Hooker (1817–1911) who explored Darjeeling District and the Sikkim Himalaya in 1848–9.

I had long hoped to visit Sikkim. Living on the Kilmacurragh Estate, surrounded many veteran rhododendrons collected by Joseph Hooker over 160 years ago, my great hope was some day to see the same species in their spectacular native mountain habitats.
We reached Darjeeling by night, and therefore had to wait till dawn to see the stunning scenery that has made this old colonial town world famous. Darjeeling is perched on a ridge at an elevation of 2,135m (7,005ft), and the scene is dominated by Mount Khangchendzonga just 45 miles (72km) in the distance. Sacred to the indigenous Lepcha people of Sikkim, this is India’s mightiest peak and the world’s third-highest mountain, at a staggering 8,598m (28,209ft).

While based in Darjeeling Hooker stayed with the British naturalist Brian Hodgson (1800–94), for whom he named the tree-like Rhododendron hodgsonii. Brian Hodgson’s bungalow is now the Rectory of St Paul’s, the most affluent private boys’ schools in India. When the Scottish plant hunter Robert Fortune introduced tea to India in the mid-nineteenth century he also brought seedling trees of the Japanese cedar, Cryptomeria japonica,  and one of these, now a mammoth tree, still grows beside Hodgson’s house.

Within fifty years of Hooker’s visit to Darjeeling, the forests had been felled to make way for tea plantations and one has to travel a considerable distance from the town to see undisturbed forest. Therefore, one of our first ports of call was Mount Tonglu, which lies south-east of Darjeeling on a ridge straddling the Nepalese border.  This area was first explored botanically by Joseph Hooker in May 1848, and he always regarded it as one of the great highlights to his visit to India, as did we.

Tonglu is a good two-hour drive from Darjeeling, through deep river valleys and narrow mountain ridges.  Quercus lamellosa was one of the most common trees along our route, and its thick, gnarled moss-laden branches were festooned with several epiphytes such as the gorgeous autumn-flowered orchid Pleione praecox. Other common epiphytes included Agapetes serpens, an ericaceous shrub with a swollen turnip-like base to its lower stem (presumably to store water in the dry season), and the glorious Rhododendron dalhousiae, collected by Hooker on Tonglu in 1848 and introduced by him from Sikkim in 1850.

On the summit, a dozen Rhododendron species, particularly Rhododendron arboreum var. cinnamomeum clothed entire mountain slopes, and we were told that in spring the blossoms come in shades of white, pink and crimson-red, creating a dazzling effect that may be seen from miles away.

Other good garden plants included Sarcococca hookeriana, Gaultheria hookeri (laden with wonderful cobalt-blue, pea-like fruits) Stachyurus himalaicus, Rubus lineatus, Hydrangea heteromalla and Hypericum hookerianum.

Closer to the summit at 3,072m (10,078ft), the panorama of the great Himalayan range opened before us as we marched through Rhododendron and Magnolia forest. To the north-west, Mount Everest, on the Tibet–Nepal border, rose its great snow-clad peak, and the scene of enormous snowy mountains piercing the sky continued as far as the Sikkim–Bhutan border, a sweep of several hundred kilometres across the greatest mountain range in the world.

Passing a boggy flat ridge full of Iris clarkei and Primula capitata, we descended into a forest full of the glorious Magnolia campbellii Alba Group; that aristocratic member of this noble genus of flowering trees. Beneath its canopy  grew Daphne bholua in thousands. I can only imagine the glorious sight that this forest must make when covered in enormous white blossoms in early spring, or the glorious scent that must pervade the woods during the same season, when the many thousands of Daphne bholua are in bloom.
Hooker described Sikkim as ‘the perfect microcosm of the Himalaya’, an apt description for this tiny Indian State that’s sandwiched between Nepal and Bhutan, with the Tibetan Plateau to the north. Sikkim contains every possible vegetation type from tropical valleys along the Tista river to alpine screes on the Tibetan frontier..

North Sikkim is Buddhist country with many spectacular monasteries, particularly in the west, along the famous ‘via sacra‘, a long narrow ridge on which are perched the 18th century golden-roofed gompas of Sanga Choeling, Tassiding and the most famous of all, Pemayangtse. Rare trees abound in the gardens of these wonderful establishments, most notably the great Kashmir cypress, Cupressus cashmeriana,  rising through the white-washed stupas at Tassiding.

Over three and a half centuries old, they were sketched by Joseph Hooker in 1849. Today their trunks are fatter, tonnes of epiphytic orchids and ferns have created high-rise aerial gardens in their boughs and their pendulous, grey-blue, frond-like sprays of foliage contrast brilliantly against the gentian-blue skies behind.
North-east Sikkim is unmissable for visiting energetic plant lovers, particularly the Lachen and Lachung valleys. The latter is the most easterly, and without doubt, the most spectacular alpine valley in Sikkim. Home to the Lachungpa people who graze their yaks on the valley floor, Lachung extends into the Yumthang valley, its most northerly point being a mere 2km (7 miles) away from Tibet.

Our base for exploring the valley was the pretty village of Lachung, surrounded by peaks heavily clothed with dark forests of Abies densa, mahogany-barked Betula utilis, Picea spinulosa and the wonderful Himalayan hemlock, Tsuga dumosa. We arrived to witness Larix griffithii donning a spectacular autumnal gown of russet orange needle-like leaves.

The gorgeous Rosa macrophylla is common in this part of the eastern Himalaya and carried a fine crop of large, pendulous, flask-like fruits. Abies spectabilis, one of the most beautiful of all the firs, was common here, reminding me of the giant old specimen in the Deer Park at Kilmacurragh. Rhododendrons abound in the upper Lachung valley, in a wide range of species, Rhododendron thompsonii is perhaps the most spectacular, creating impenetrable thickets with its beautiful peeling, mahogany-coloured stems. In places in spring, its waxy blood-red bell-shaped blossoms paint the valley floor blood-red.

The superb Daphne bholua, at this altitude a deciduous shrub, appeared by the roadside bearing whitish-pink blooms, heavily laden with the most beautiful, spicy lingering scent. But there is much more at various seasons: cobra lilies, giant Himalayan lilies, wonderful corydalis in a bewildering range of colours, primulas like Primula denticulata and Primula sikkimensis fill the alpine meadows in tens of thousands among blue and white anemones.

Yumthang is aptly known as ‘the valley of flowers’ and is without doubt, the most spectacular upland area of Sikkim. Glaciers and frozen waterfalls descend from the cliff-like jagged peaks that box the valley in. A common shrub here included Berberis virescens, a plant that wowed our party with its stunning red stems that seemed to glow in the low November sunlight. This species was described from flowering and fruiting material, sent to Joseph Hooker at Kew, by Thomas Acton (1826-1908) who grew plants at Kilmacurragh, Co. Wicklow. These presumably were raised by Sir Frederick Moore (1857-1949) at Glasnevin from seeds collected by Sir Henry Elwes (1846-1922) during his first visit to Sikkim in 1870. It is a common roadside shrub in north-east Sikkim, being particularly abundant in the Lachen and Lachung valleys.

As we descended the valley late that evening we witnessed one of the great Himalayan scenes for which this part of north-east Sikkim is famous. All about us were soaring jagged snow-capped peaks, frozen waterfalls, glaciers, and enormous landslides. Suddenly, as dusk descended, the valleys and dark fir-covered ridges beneath us were enveloped in a sea of mist, and finally, after a brief wait, the upper snow-clad peaks of the mighty mountains were swallowed in a dense cumulus. That night, we fell into a well-earned sleep in the little village of Lachung to the roar of the Lachung river, a great glacial green torrent lined by enormous water-worn boulders.
From Lachung our travels took us to the neighbouring Lachen valley. The scenery here is a little more tame, though for plants it is equally interesting. The lower valley is warm temperate and in November (the time of our visit), the mountainsides are painted pink by the dazzling display created by the autumn-flowered Prunus cerasoides.

Gradually temperate plants suited to the Irish climate appeared. Trees like Acer sikkimensis and Tetracentron sinense painted the slopes yellow and amber and the giant fronds of the Himalayan chain fern, Woodwardia unigemmata,  draped the steep roadside slopes. Schefflera rhododendrifolia gives an exotic air, forming multi-stemmed trees over 15 m. high with enormous sprays of digitate foliage.

The village of Lachen is beautifully located in a steep sided heavily forested valley; a scene reminiscent of the Swiss Alps, though the mountains here are far higher than their European counterparts. Good garden plants abounded  even on the village edge, the ghostly-white stems of Rubus biflorus became a familiar sight and its bedfellows included Hippophae salicifolia (10 m. tall trees laden with orange-yellow berries), Clematis montana, Daphniphyllum himalayense, the pretty little ginger-relative Roscoea auriculata, Morina longifolia and Primula capitata, for example.

A two hour drive above Lachen lies the tiny yak station of Thangu and the spectacular Chopta Valley, the last point of human habitation and the furthest a foreign expedition may travel towards the Tibetan border. Our route through this snowy landscape brought us past enormous waterfalls that cascaded like silver threads into the turquoise waters of the Lachen river below us.
We soon drove above the tree line & reached the village of Thangu at 4267 m. (14000 ft.). Just beneath village lay ‘Hooker’s Rock, surrounded a few small ploughed fields; the only sign of cultivation in the region. On the edge of these fields we spied the dead flowering stems of one of Hooker’s most famous introductions – Primula sikkimensis. Above Thangu lies the spectacular Chopta Valley, another valley of great soaring peaks, streaked with glaciers and ice fields.

The upper part of main valley was crisscrossed by ancient moraines on which Rhododendron campanulatum ssp. aeruginosum had formed enormous colonies, and scattered in the shelter of the rhododendrons, were alpines like Fritillaria cirrhosa, Rhodiola fastigiata, Gentiana stylophora (a giant gentian with enormous bell-like yellow blossoms) and Meconopsis paniculata (syn. M. nepaulensis) in its yellow form. Rhododendron setosum turned the mountainsides an ochre hue, with its autumnal aromatic foliage. Its bedfellows included the equally aromatic Rhododendron anthopogon, Cassiope fastigiata, Juniperus pseudosabina (all burned as incense in local monasteries) and Berberis angulosa.

The latter was introduced to cultivation by Colonel Charles Ball-Acton (1830-1897), an Irish soldier  who sent seeds from his base in Kashmir, to his brother, Thomas Acton at Kilmacurragh, who first flowered it in 1888.This widespread barberry was common in the Chopta Valley, where it had assumed a fiery-orange autumnal hue and I departed the area pleased to see a ‘Kilmacurragh plant’ thriving in its native Himalayan home.
Our journey through India ultimately took is to the wonderful Taj Mahal at Agra, built in the 17th century using white marble carried on the backs of elephants from Rajasthan over 450 miles away. Persian flowers like the crown imperial, iris, poppy, lilies, narcissus and tulips are beautifully carved into the marble, while inside the mausoleum familiar garden flowers like chrysanthemums  are created using inlaid semiprecious stones gathered from across Asia. The Taj Mahal is undoubtedly the most sublimely beautiful building in the world, we strolled through its Mughal gardens at dawn, through exotic tropical trees, as the rising sun lit the white marble an amber-pink hue. India – incredible India!

This article first appeared in Garden Heaven, 2014.