Get a Rheum! Plant Hunting in the Himalayas

‘It is the most wonderful looking plant in the whole of the Himalaya and excited my unbound admiration like no other,’ wrote Joseph Hooker to his father in 1849. He was referring to Rheum nobile, a rare and curious plant that looks like a sun-bleached over-excited cabbage.

Image of Rheum nobile from Joseph Hooker's diaries

Joseph Hooker was a “brilliant Himalayan plant explorer” best known for collecting rhododendrons. But it was rheum, not rhododendrons that stole his heart in the Himalayas. In another letter home to his father (Kew Gardens director William Hooker) in response to news of the rhododendron seeds he’d collected sprouting at Kew Gardens, he wrote ‘I rejoice at the Rhododendrons growing but I would for my own sake ten times rather see Tchuka Rhubarb as it grows here.’

167 years later in 2016, Chris Brown, then a student of horticulture at Kew Gardens in London, read Hooker’s words and decided to track down this botanical oddity in the mountains of Bhutan as part of his final year of study at Kew. Whilst other students visited gardens in easily accessible locations, Chris (accompanied by six horses, a horse handler, a cook and a guide) traipsed around the remote mountains of northern Bhutan, hunting for a very strange plant that grows in a very specific location within a very remote part of the world. “It felt like a proper Victorian style plant hunting trip”.

Chris Brown spent fourteen days plant hunting in the mountains of Bhutan
Rheum nobile

Rheum nobile is not an easy plant to find. Chris began by contacting the botanic gardens in Bhutan. “They had a rough idea of where the plant might be found in the wild and gave me some advice.” Chris headed to the Jigme Dorji National Park in the north east of the country, to explore areas around ancient trade routes between India and Tibet.

He and his gang of horses, cook, horse handler and guide climbed mountains, forded glacial streams and explored untouched valleys pulsing with botanical life. Chris was awestruck. “I didn’t really know what to expect. Not many people have been up to those regions looking at plants, except the Bhutanese. Most of the valleys are unchartered territory.”

For a plant hunters’ perspective, it’s a dream location. It’s massively biologically diverse and an evolutionary hot spot.”

“I could have spent the whole time in one valley, there was just so much to see. A lot of the plants I might have known the genus or species, but a lot more I didn’t.” But Chris couldn’t stop, he was a man on a mission. Instead of rolling around happily in plant packed valleys, he was hunting rheum.

Chris and the woman who helped him find the rheum

Chris and his plant gang climbed mountains and drank yak butter tea with nomadic Tibetan yak herders, showing them pictures of the plant and asking if they had seen it in their travels. Many hadn’t. But eight days into his fourteen-day trip, Chris struck gold. He met a woman who told him where it was. Chris was ecstatic and took a photo together with her. It was the first time she’d ever had her picture taken or seen a camera.

At 4780 meters above sea level, and after climbing four mountains, they found it. “It was mind-blowing. We had to cross a glacial river to get to it. It was just a great feeling, we couldn’t believe we had found it”. I’d cry, I tell Chris, if I were in his shoes. Being a stoic Englishman there were no tears, he tells me, but “there was a little bit of emotion.”

It was an emotional adventure. It was wild. We were fully immersed in the wilderness. The only way out was helicopter extraction, and the nearest helicopter was from India.”

But back to the rheum. According to Chris, it has a symbiotic relationship with a fungus gnat – the plant produces excessive seeds, more than it needs to reproduce, and the gnat eats the seeds. In return for food, the gnat pollinates the flowers, and so it goes. “The fungus gnat is believed to be the only species that pollinates the plant.”

“The flower spike is hidden under the white leaves/bracts. They create a greenhouse effect. It’s a microclimate – warmer and more protected by the wind. It’s believed the leaves protect the flowers from the harsh light as it can affect the pollination process.”

Whilst one of Chris’s primary aims of the trip was to find Rheum nobile, it was also about exploring and documenting the plant communities and habitat types along the way. “It was so diverse – we saw many different forest types, open glacial meadows, all sorts of different plant habitats.” Physical plant collecting is not allowed in Bhutan, so Chris collected data which he shared with Kew Gardens.

The trip has whet Chris’s appetite for more plant hunting. He’s thinking Yunnan province, in China, might be his next plant hunting target. In the meantime, he’s working as a gardener at Gravetye Manor, a 35-acre historic garden in the gentle English countryside south of London. It’s a far cry from the extreme landscapes of the Bhutanese mountains, but Chris has bought a little bit of the Himalayas home. “I see a lot of plants every day that I saw in the mountains in the wild. I have been buying seeds and taking cuttings from others. I’ve been building up a little collection of my favourite plants from the trip. I’m hoping to introduce a few of those in the garden at Gravetye.”

Chris Brown is a bona fide plant lover, hunter, and cultivator. He’s worked with plants all his life, and like most of us green-thumbs, sees gardening not just as a job, but as an enduring passion. “Gardening is my life. It’s all I do. I finish work and go home and do more gardening.”

As Chris has experienced, connecting the dots between wild and cultivated plants, between different cultures and times, is what the act of gardening does best. It’s a link to the earth and each other like few other pursuits. And the best thing? Everywhere – from the mountains of the Himalayas to suburban carparks – is a potential plant hunting location. “That’s what I love about being a plant person. You can be in a carpark in the middle of nowhere and there’ll be some botanical oddities growing, if you look hard enough.”

All photographs taken by Chris Brown.

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