A miniature West Coast juniper "forest" grows in a dish but looks so ancient and gothic you can almost see the mist. A wizened red maple that has dropped its leaves for winter is small enough to be a prop for a model train display.

These tiny but full-grown trees and 51 others make up the new National Collection of North American Bonsai, which opened at the National Arboretum in Northeast Washington last fall. The trees were collected last year by Bonsai experts, who traveled across the country looking for the finest American-grown trees to exhibit at the arboretum, the nation's official tree garden.

The collection is the newest of three Bonsai collections housed at the arboretum. A Japanese collection of approximately 50 trees was given to the American people in 1976 to celebrate the country's bicentennial. In 1987, a donation of 31 Chinese miniature treescapes became part of the collection.

The three collections, which include trees as old as 350 years, are considered the most comprehensive Bonsai assemblage in the Western hemisphere.

"We are just beginning to come into our own in this ancient art," said curator Robert F. Drechsler.

Chinese and Japanese growers have produced Bonsai masterpieces for centuries, but U.S. growers did not begin experimenting until the 1950s.

Soldiers who occupied Japan after World War II brought back examples of the tiny trees and inspired a few West Coast gardeners to begin pruning branches and roots to produce their own bonsai.

The movement spread slowly east and came to the Washington area about a decade ago. Five bonsai shops here provide area growers with containers, special soil mixtures and other supplies.

Now, decades after the first American bonsai trees were being "trained," the results are coming in and the botanical community is pleased with what it sees.

Most of the 53 trees selected reflect the strong Japanese influence still typical of U.S. bonsai: a twisted conical trunk with branches spiraling upward in groups of threes. But hints of an American look are emerging.

"I'm not sure there is an American school yet, but American-grown trees tend to be more wild-looking, more rugged, less structured," said William J. Spencer, a spokesman for the 300-member Potomac Bonsai Association.

That's mostly because of the conditions U.S. bonsai growers face, he said. There are no U.S. nurseries owned by generations of bonsai stock producers like there are in Asia, so U.S. growers must collect native trees from the wild.

"When you have to get your material that way, you get what you get and the result is different," Spencer said.

When U.S. growers go out looking for bonsai material, they search for trees that have been naturally stunted, perhaps by alpine winds or regular nips from passing deer.

One tree in the new collection became bonsai material after its owner repeatedly climbed on it, breaking its branches while painting the eaves of his California home.

About a third of the arboretum's total collection of 150 bonsai trees is on view. Another third, which need protection from Washington's harsh winter temperatures, is reserved in a heated area that staff members will open upon request. The rest are tropical trees that must spend the winter in the arboretum greenhouse, which is closed to the public.

"Even though you can't see all the trees at this time of the year, it's still a good time to come," said horticulturalist Daniel Chiplis, one of the collection's staff members. "The winter form of some of these trees shouldn't be missed."