Like any conscientious guardians of an acclaimed beauty spot, the gardeners at Black Dragon Pool have erected gentle warning signs for visitors: "Please do not pick up flowers" and "Be aware the grass is napping". How different it was just seven or eight decades ago when the remote mountains of Yunnan province in south-western China were little known in the West, except to a handful of intrepid botanists.
At the height of the plant-hunting era, a century or so ago, British commercial nurseries, the Royal Horticultural Society and botanical gardens such as those at Edinburgh and Kew, commissioned explorers to penetrate unknown, and often dangerous, lands in search of new species that could be grown here in the UK. The plant-hunters brought back exotic species that are familiar in our gardens today; lilies, azalea, clematis and peonies.
To give a sense of the challenge: even in the 21st century, reaching this corner of China scrunched up against the border of Burma and Tibet is a quest involving many hours of travel by air and road. But Yunnan's boast that it is "Tourism Paradise of the World" intrigued me. So, I decided to join a tour on the inspired theme "In the Footsteps of Plant-hunters", then scurried off to the library to find out about these botanical pioneers.
Two of them were George Forrest and Joseph Rock. Among the plants that Forrest introduced to cultivation was the Rhododendron giganteum, a discovery as exciting to a plant-hunter as the fabled giant squid to a seafarer.
Joseph Rock, an Austrian-American eccentric, carried out his plant-hunting in Yunnan between 1922 and 1949 (when he was forced abruptly to flee as Mao's revolution created the People's Republic). Undaunted by bandits roaming the hills, winter blizzards, landslides and the effects of altitude, Rock would set off from his base in Lijiang, assisted by local Naxi men and nomadic Tibetan escorts. He collected sacks of seeds and roots to ship back to his patrons and is reputed to have brought back nearly 500 species of rhododendron from a single expedition.
The romance of plant-hunting seems remarkably close when you visit Rock's house in the forgotten village of Yuhu, about 15km north of Lijiang. The timbered and shuttered house is built around a tranquil courtyard, fittingly adorned with flowers and a mosaic floor. Up a narrow ladder-like staircase, his spartan but light-filled bedroom with camp bed, trunk and writing desk makes it easy to imagine he's just slipped out to check on his yak and pony caravan. The dimly lit museum downstairs haphazardly displays his pack saddle, horse bells, whip and lanterns. There are also issues of National Geographic to which he contributed, and a fascinating collection of his photographs. One shows Naxi men using inflated leather flotation bags to help them swim across the Yangtze; another depicts a strange tribal ritual to appease the spirits after a lovers' suicide pact.
Lijiang itself is impossibly picturesque: you see why it is now a honeypot (and honeymoon) resort for Han Chinese. The pedestrianised old town is a maze of cobbled lanes, stone bridges over winding streams and canals, and wooden houses with flower-filled courtyards.
In the evenings you can barely move for tourist throngs. Yet, wandering to the periphery can bring delightful surprises, such as the trio of pools at Baimalong where women and children wash clothes, or hole-in-the-wall restaurants where home-made wine and liquor distilled from local fruits and fungi is dispensed from glass flagons. Beware jars of "plum wine" whose potency is more slivovitzian than vinous.
After we'd successfully tracked down a plant-hunter, it was time to hunt for plants. We drove north in the direction of Tibet, stopping first at Shigu. Every third day, locals (and almost no tourists) stream into the market at Stone Drum Village, near a hairpin bend of the headwaters of the Yangtze, to buy and sell piglets squirming in sacks, competing brands of packaged piglet food, trussed chickens, rape-seed oil and multiple grades of rice being assessed by canny housewives, and delicious seasonal fruit such as bayberries which look like raspberries and have a texture akin to lychees.
Wizened tribal women filled the wicker baskets tied to their backs with foot-long green vegetables and plastic toys, while husbands smoked cigars upended in the bowls of their pipes. A couple advertising on-the-spot dentistry were waiting for customers while a medical man applied a poultice to a woman's hand and a turbaned gentleman resembling a pantomime charlatan sold powdered plants and medicinal mushrooms. A lady with long blackened toenails danced a jig to the tinny music from a cheap tape machine round her neck.
This market is known to sell Cordyceps sinensis, dried caterpillars infected by a parasitic fungus considered by many Chinese to be a cure for cancer, ageing and everything else. Although clinical trials have failed to prove health benefits, people still buy it at twice the price of gold.
Passing through the dramatic landscapes of Leaping Tiger Gorge, popular with trekkers, we drove north into Deqen Tibetan Autonomous Prefecture. Despite the name, this is still part of Yunnan rather than Tibet as defined by the boundaries that prevailed after 1950, when Tibet was annexed by China.
A tourism billboard enticed us on: "Heaven is too far away – come to Shangri-La". The most recent contender to throw its hat in the ring to be identified with the land of enchantment conjured in James Hilton's 1933 fantasy novel Lost Horizon is the town of Zhongdian, capital of Deqen. A decade ago, the council persuaded the Chinese government to allow it to change its name to Shangri-La to boost tourism.
On arriving in the sprawling outskirts, you will be tempted to think that the new name is somewhat far-fetched. But reserve judgement. A few kilometres north of the modern town, you can stay at the Songtsam Retreat. Fling open your room's traditional shutters, breathe in the crisp mountain air, admire the golden-roofed Songzanlin Monastery across the valley, and you can easily convince yourself that you are having a Shangri-La moment.
China's first national park, deemed in 2007 to meet international standards, is Pudacuo – less than an hour away from Shangri-La. When I visited in June, the 20-day flowering season for rhododendrons had just finished, but the low-growing alpine azalea – 300 of the world's 800 species are found in Yunnan – painted the hillsides as purple as a heather-clad moor. After passing through a meadow, the park boardwalk runs alongside Shudu Lake which reflects the vast coniferous forests and surrounding peaks.
We spotted wood anemone, potentilla, marsh marigold, primula, clematis and meconopsis (poppy) but were too early for the trumpet-shaped blue gentians which bloom in profusion. The trees were also beautiful, including copper birch, eastern oak, rowan (one variety is called Sorbus "Joseph Rock") and firs draped in Spanish moss which is a sure sign of ecological health.
After revelling in this protected wilderness, it was a shock to run the retail gauntlet as you exit the park, where all manner of souvenirs and traditional medicine is on sale. A more tempting purchase is the fermented tea from Pu'er, in the south of Yunnan, which is famed for its medicinal properties. A small round of compressed high-grade Pu'er tea fetches the equivalent of £25.
A quite different beverage is yak-butter tea. Joseph Rock compared it to "liquid salted mud", but if you think of it as a salty roast barley soup or a savoury Ovaltine it seems quite palatable. A modest wine industry also flourishes, left over from when French missionaries planted vines in the mid-1800s. Judging by how dusty the bottles on cornershop shelves are, locals aren't keen, though who could resist trying a full-bodied red glorying in the name "Enduring Pulchritude"?
Over the course of Rock's colourful career, his interests also encompassed ethnography. Of all the ethnic groups of Yunnan, Rock was primarily interested in the Naxi who still cling to their shamanistic culture today. Every night ancient Naxi music is kept alive by almost equally ancient Naxi musicians. But this musical tradition came close to annihilation during Mao's Cultural Revolution when the orchestra's leader Xuan Ke was imprisoned for 21 years.
There's a museum devoted to Naxi culture at Black Dragon Pool. The Dongba Cultural Museum celebrates the long tradition of the Dongba masters, the scholar-priests of whom only a handful survive and who alone can interpret their pictographic scripture. The highlight of the museum is a funeral scroll painted on a piece of white starched calico 14m long, depicting demons, deities and animals on the Road to Heaven. Visitors to northern Yunnan travelling the road to Shangri-La may not spot demons or deities, but they will discover a land of wine and primroses, yak milk and honey.
Susan Griffith travelled as a guest of Journeys of Distinction (0161‑491 7616; jod.uk.com) which offers a 14-day limited-edition group tour "Footsteps of the Plant Hunters" from 14 April 2013. The price of £3,995 per person includes return flights from Heathrow to Lijiang via Shanghai, on Virgin Atlantic, and Kunming, on China Eastern Airlines; road transfers, luxury accommodation with breakfast; and sightseeing tours with an accompanying tour manager and local guides.
A single-entry tourist visa to China costs £66 including service fee. Apply through the Chinese Visa Application Service Centre (020-7842 0960; visaforchina.org.uk), which has offices in London and Manchester.
Yunnan Provincial Tourism Administration: en.ynta.gov.cn.