Gardeners like to think of themselves as rooted in continuity, unmoved by trends. It may be true for us in clothes or music, but when it comes to plants, we're drawn to the latest, most exotic varieties.
This hunger for the new is as old as horticulture itself. Thirty-five hundred years ago, Queen Hatshepsut of Egypt sent collectors off to search for a little something new for the royal gardens. Her plant squad dug, balled and hauled home 32 incense trees.
Today, armed with a permit and a voracious appetite for new plants, plant explorers such as Dan Hinkley of Heronswood Nursery Ltd. in Washington and Dan Heims of Terra Nova Nurseries in Oregon comb the globe.
Some of their discoveries are unusual varieties of old favorites, such as the wonderful black pussy willow (Salix 'Melanostachys'), a Japanese native whose furry black catkins are embroidered with crimson, and Arisaema griffithii, a Nepalese jack-in-the-pulpit whose deep maroon hood looks like a butterfly's wing filigreed with lime green. Others are exotics, such as the 6-foot Cardiocrinum giganteum, which looks as though it rose from the primordial ooze.
Ends of the earth
It's on-the-ground work. Plant explorers pick their way through New Zealand, where the rhododendrons are 35 feet tall, trek through the steamy heat of Mexico, scour the misty valleys of China, and climb the mountains of Nepal.
"Mountains are a tremendous place to find plants," says Heims, 46. "You can find gorgeous heucheras at 11,000 feet."
Heims began his collecting in college with a single velvet plant (Gynura sarmentosa), which he propagated himself.
"By the end of senior year, I had 2,000 houseplants," he says. "I was smitten."
Heims now propagates primarily by means of tissue culture, which involves taking a piece of plant the size of a rice grain and growing a new shoot in agar.
To enlarge the variety of his offerings, he began to travel. Before each trip, Heims contacts plant specialists, breeders and nurseries in each country to find out what's new. Japan, which has deeply ingrained horticultural traditions, is a particular favorite.
"I found 500 plants in one Japanese nursery that I didn't know," says Heims, who is working on a book for Timber Press about heucheras and tiarellas, whose shimmering burgundy leaves and delicate flower fronds grace many woodland gardens.
Hinkley says, "The Japanese have bizarre aberrations from the species that are extraordinary ornamentally, so it has a treasure trove of plants for our gardens."
Hinkley, who has loved plants since he was 3, began collecting them in his childhood. For the past 20 years, the co-author of "The Explorer's Garden" (Timber Press, 1999) has been going around the world to collect them.
Getting to the treasure trove is one thing. Getting home with the treasure intact is another. Queen Hatshepsut's plant collectors packed the incense trees in wicker baskets, which they carted across half a continent. Amazingly, all but one made it back to Luxor alive.
Today, federal regulations decree that plants must be free of soil to prevent importing soil-borne diseases. So, Heims washes plant roots clean -- sometimes in the sink or toilet of his hotel room -- wraps them in newspaper, and carries them on the plane himself.
Rather than struggle with keeping plants alive, Hinkley primarily collects seed. His reasons are both practical and ethical. Seed is a more portable package than a plant. And he doesn't like putting even one native plant at risk.
"I find it difficult to justify taking plants out of the wild," says Hinkley, 46. Taking seed leaves the original plant to continue reproducing in its natural habitat.
Not that collecting seed is any simpler than washing roots. In Nepal, Hinkley spent one night huddled in a rain-soaked tent hand-picking detritus, dirt and bugs from seed by lamplight. The reward for all this work is viable seed that Hinkley not only germinates for his trial gardens at Heronswood but shares.
"All of my collections ultimately go to some botanical garden," he explains. "University of Washington Arboretum always gets a full share and Strybing Arboretum in San Francisco will receive a lot. I also send them off to friends, colleagues and botanical gardens around the country."
To prevent explorers from taking threatened plants, the international endangered species list identifies plants whose distribution between countries is prohibited. Another consideration for the plant explorer is a new plant's potential for invasiveness in its new habitat. For example, the Asian kudzu vine, once hailed as the answer to erosion, was planted wholesale by soil conservation districts around the country. Unfortunately, the kudzu later began to suffocate whole sections of native woods.
To prevent distributing invasive plants, Hinkley not only grows them for several years, but consults Susan Reichard, an ecologist at the University of Washington's Center for Urban Horticulture. One recent Reichard reject is the seductively beautiful Ligustrum delavay-anum, a privet.
"I started it from seed and it had been growing in my garden for four years," says Hinkley. But when Reichard checked it against her computer model, it sent up all kinds of red flags that it would be extremely invasive. So, despite its beauty, Hinkley dug it up and burned it. Afterward, they found "masses of seedlings," confirmation of its domineering personality.
Sources for plants or seeds
Heronswood Nursery, Ltd.
7530 NE 288th St.
Kingston, Wash. 98346
Terra Nova Nurseries
12162 SW Scholls Ferry Road
Tigard, Ore. 97013
Home Farm Nursery
11351 St. James Road
Worton, Md. 21678
(Orders from both nurseries)