Some of the most familiar plants in the garden originated in Southeast Asia. Azaleas, rhododendrons, hostas, wisterias, lilies, day lilies, camellias and viburnums, to name a few, have made us feel so much at home that our world, ironically, would feel alien without them.
Many of these plants have cousins native to North America, but it is the trove of Asian plants that directly, or indirectly through hybridizing, have come to define our gardens: the showy flowering evergreen azaleas, the saucer magnolias and the colorful blossoms of the hydrangea and crape myrtle.
Japan, Korea, Taiwan and the southern provinces of China west to Tibet, as well as Bhutan and Nepal, drew 19th and early 20th century plant collectors from the West who found in these regions a horticultural Shangri-la. The ice age glaciers that erased much of the flora of Europe and North America were blocked by the Himalayas and other mountain ranges. The result? "The number of plant species within the boundaries of China is 10 times the plant species we have in North America," says Dan Hinkley, whose 5-acre garden overlooking Puget Sound in Washington state has, it is fair to say, its share of these treasures.
Hinkley, 55, has spent two decades retracing the steps of such legendary plant explorers as Robert Fortune (1812-80), Jean Marie Delavay (1834-95), Armand David (1826-1900), Ernest "Chinese" Wilson (1876-1930) and George Forrest (1873-1932).
Theirs may have been the golden age of Asian plant collection, but the spirit of the period is very much alive among a handful of 21st century collectors such as Hinkley. His work may take decades more to flower in Western gardens, but the tradition, the impulse to brighten our lives with fantastic Asian plants, persists.
Hinkley's forerunners stayed for years in Asia, often assembling armies of local inhabitants in their quest. They faced perils and privations Hinkley hasn't, including disease and physical threat, but they had certain advantages. They could evaluate plants in spring or summer bloom. Hinkley typically goes for 12-week stints in two or three countries, but during the seed-ripening months, September through December. He only sees how they bloom back in his garden, sometimes years later.
There is a cousin of the climbing hydrangea with the unfortunate name of Schizophragma hydrangeoides. It is a magnificent leafy vine that, in my garden, took about seven years to bloom. In 1999, Hinkley took the seed of a close relative named Schizophragma integrifolium variety fauriei, whose blooms are twice the size but only now are fully unfurling for Hinkley for the first time. Wilson described this Taiwanese plant as "the most beautiful of the deciduous flowering vines from Asia," Hinkley says. "It has enormous impact."
Then Hinkley collected the seed of a mystery tree in central Japan, and it finally flowered to reveal itself as something called Pterostyrax corymbosa, a fairly ornamental tree, but if it were a fish, you might throw it back. "In some ways it was a much more exciting plant when you didn't know what it was for all those years," he says. "It's like an unwrapped Christmas gift, and then you open it and it's knitted mittens."
A decade ago, Hinkley wrote a book titled The Explorer's Garden: Rare and Unusual Perennials, which describes the novel herbaceous plants he collected in his travels. A month ago, he published a sequel, The Explorer's Garden: Shrubs and Vines From the Four Corners of the World (Timber Press). As the subtitle suggests, it also includes woody plants from other countries, namely India, Australia, New Zealand, Chile, Costa Rica and South Africa.
His finds in beguiling Southeast Asia, including northern Vietnam, represent a majority of the plants featured in the new book. Vietnam, he says, "is fascinating and one of the most unexplored areas botanically for plants appropriate for (parts of) North America," including the stretch from coastal New York to Florida. Many of the plants are tropical or subtropical but are winter hardy in the mid Atlantic because they grow at high elevations.
Not every plant in the wild, however, is a good candidate for the garden (Floridians need only consider Brazilian pepper, an invasive species that chokes out native species); quite the contrary. "Novelty is one of the least important things to look at when you're bringing plants into cultivation," he says. Hinkley, founder and former owner of Heronswood Nursery (heronswood.com), is looking for plants that will show and behave well in the garden.
He sees his role as not only bringing a wider plant palette to North American gardeners, but also increasing the genetic diversity of ornamental plants. In 1996, he collected seed of a clematis named Clematis repens, which Wilson had collected in 1903 but which fell by the horticultural wayside. "Things are lost," Hinkley says. "Just because they have been in cultivation in the past doesn't mean they're still there."
"We'll see a lot of these plants used in breeding programs," says Nicholas Staddon, director of new plant introduction for Monrovia, a major wholesale grower based in Azusa, Calif. "There's a current, though, that possibly the best is yet to come out of China."