DC's living museum: this 446-acre tucked-away national botanical treasure is more than just another pretty face.

Many of the half-million annual visitors to the U.S. National Arboretum are surprised to find this botanical treasure in the nation's capital. Many have heard or read about it, but not seen what it has to offer--446 acres of rolling hills, open meadows, and gentle riparian slopes; more than 20,000 labeled plants; more sights--and scents--than a person can absorb in one day.

But the Arboretum's work goes far beyond its beautiful vistas and blooms; most people do not see the bulk of what the Arboretum stands for: developing new and improved ornamental plants.

Hybrid crapemyrtles with intriguingly mottled bark and hot pink flowers resulted from a project to breed hardiness, disease resistance, and more ornamental features into this small tree, using wild collected species from Japan. A stately young American elm represents more than a decade of work developing specimens resistant to Dutch elm disease, which decimated this popular street tree. Winter-hardy camellias claim a parent collected in China and grown at the Arboretum by a staff botanist.

[ILLUSTRATION OMITTED]

As part of the U.S. Department of Agriculture's Agricultural Research Service, the National Arboretum has as its mission research and education on ornamental plants. It's a direct response to the both public and environmental need for attractive low-maintenance landscape plants. But the significance of its work goes deeper than that.

Breeding work on woody plants can use up the better part of a scientist's career. "It can take decades to see a hybridizing project through from start to finish," Arboretum tree researcher Richard Olsen explains. "You figure on a few years to select appropriate parents, do the crosses, and germinate the seeds. Then it's five to 10 years for the seedlings to mature into fertile adults. Maybe three to five more years to evaluate individual trees for ornamental and disease factors.

[ILLUSTRATION OMITTED]

[ILLUSTRATION OMITTED]

"Promising selections go to cooperators to field test for another three to five years," Olsen continues. "If all goes well, the plants that prove worthy must be propagated and grown to saleable size before being offered to the public--another three to five years." The Arboretum does what commercial growers cannot afford to do: wait patiently for breeding results.

Throughout its almost 80-year history, the Arboretum has introduced more than 650 new cultivars (short for cultivated varieties), most the result of long-term research. Among its most popular introductions are the crapemyrtles, all named after Native American tribes, including recently released dwarf types. Other now-standard nursery offerings are 'Cayuga' viburnum, 'Sparkleberry' holly, 'Blue Lagoon' juniper, and 'Green Giant' arborvitae. Fifteen introductions have been named Gold Medal or All-America Selection winners (see a complete list of Arboretum introductions and award winners at its website: www.usna.usda.gov).

The research field continues to foster dozens of crapemyrtles, with further selections still possible. And a few older projects are finally resulting in releases: the shrub breeding program just named two new lilacs, 'Old Glory' and 'Declaration,' and two new flowering cherries, 'First Lady' and 'Dream Catcher.'

The National Arboretum follows a rigorous review process established by the Agricultural Research Service. Meetings and workshops with stakeholders, organizations and individuals with a vested interest in the ornamental horticulture business, help identify issues and problems that could be solved through research. Throughout the life of a project, these same stakeholders, as well as peer professionals, help assess the success of the work. Researcher Olsen's new tree project is a good example of how the Arboretum responds to nursery, municipal, and public demand for street trees that can fit under utility lines and tolerate urban stresses like pollution and salt runoff.

During his graduate work, Richard Olsen worked with a promising hybrid of two native trees. Called a chitalpa, the tree is a cross between the southern catalpa (Catalpa bignonioides)--a large tree from the southeastern U.S.--and the desert willow (Chilopsis linearis)--a smaller, related species native to the Southwest. The hybrid was first made by Russian geneticists in Uzbekistan in the 1960s, however the plants weren't grown in the U.S. until the 1980s. Two cultivars are available. They perform well in the Southwest but suffer from disease problems and other maladies in the rest of the U.S.

Olsen has remade the cross using superior parents and is now looking among the hybrid progeny he brought to the Arboretum for specimens that demonstrate the best flower color, form, and pollution and stress tolerance. The hybrids can produce a tree with the hardiness range of the catalpa and with the more colorful flowers and shorter stature of the chilopsis--a good candidate, therefore, for street plantings. He hopes that 15 to 20 years from now, you'll admire one of his trees as you stroll along a city sidewalk.

[ILLUSTRATION OMITTED]

Some of the Arboretum's research isn't as obvious as a new plant. One staff horticulturist is working on problems associated with nursery and crop productions, problems such as protocols for hard-to-propagate nursery plants. Plant pathologists are tackling diseases of floral and woody crops, including methods for detecting these harmful or disfiguring organisms. Virus-vector-host plant interactions are the specialty of a staff microbiologist. Taxonomists and horticulturists maintain and study collections of dried herbarium specimens and living germplasm--the unique genetic material contained by individual plants.

This behind-the-scenes work takes a public stage in the Arboretum's world-class gardens and collections. In designed beds in the dwarf conifer collection, the vivid summer blooms of the Arboretum's introduced crapemyrtles provide a striking foil for the blues and greens of the evergreens' foliage. The 'First Lady' flowering cherry graces the Capitol Columns Overlook, a spot at the center of the grounds with a view of 22 majestic columns from the redesigned east portico of the U.S. Capitol.

Many older introductions show mature forms in the Court of Honor by the Administration Building. Seasonal spotlights move from spring flowering magnolias to summer blooming hibiscus, fall fruiting pyracantha, and exfoliating crape-myrtle bark in winter.

[ILLUSTRATION OMITTED]

As a living museum, the Arboretum offers numerous outdoor galleries filled with attention-grabbers. The National Boxwood Collection contains the world's largest collection of boxwood species and cultivars. In April, crowds pass slowly by 15,000 60-year-old azaleas in full bloom. Tour the Fern Valley Native Plant Collection with the curator in March and learn about eastern woodland spring ephemerals. Explore the Asian Collections, vicariously experiencing the thrill of collectors who found many of the plants there in regions of Japan, China, and Korea. Get close to the dinosaurs in the company of dawn redwoods, a tree that dates to prehistoric times and was thought to be extinct but found alive in China in the 1940s.

You can marvel at William Gotelli's personal collection of 1,500 dwarf and slow-growing conifers, moved in its entirety from his home in New Jersey to the Arboretum in the 1960s. Study the many uses of plants in the two-acre National Herb Garden. And take a meditative walk through 70-foot-tall cryptomerias that lead visitors into the National Bonsai & Penjing Museum--a collection of more than 100 masterpieces of bonsai and penjing, the Chinese version of bonsai.

Directing the ambitious work of the National Arboretum is Thomas Elias, whose job entails simultaneously overseeing scientists' widely varied research efforts and running a large public garden. Proud to protect and promote the work he inherited, Elias constantly seeks to move the Arboretum in new directions.

Holding a finely tuned new master plan, he points to some short-term objectives. "Improving the visitor experience is on the top of my list," he says. "Our master plan calls for a new entrance and improved and enlarged parking. It also connects our widely scattered collections with foot trails and interpretive nodes where a continuously running tram would make stops.

[ILLUSTRATION OMITTED]

[ILLUSTRATION OMITTED]

"We're trying to make more of the collections accessible, too," Elias adds. "Each year, as funding permits, we make some progress. My dream goal is to build a new visitor center, which would be the hub of expanded educational activities."

Budgeting for everything on the wish list means balancing the need to improve existing aging infrastructure while chipping away at new construction. Support from stakeholder groups like the Friends of the National Arboretum and the National Bonsai Foundation, which seek both private and federal funds for the Arboretum, helps launch projects like a new Flowering Tree Walk and accessible courtyards in the bonsai museum.

As a typical day at the Arboretum winds down, horticulturists collect their garden tools, scientists shut down the labs, education staff complete preparations for the next day's programs, and visitors head to their cars. Often, too, a solitary figure, hands clasped behind his back, lingers in one of the gardens or collections. He nods back to calls of "Good night, Dr. Elias," but his faraway look says he's dreaming about what the Arboretum can accomplish next.

The U.S. National Arboretum, at 3501 New York Ave., NE, Washington, DC, is free and open daily from 8 a.m. to 5 p.m. (except December 24). The National Bonsai & Penjing Museum is open from 10 a.m. to 3:30 p.m. daily. Visit www.usna.usda.gov.

Nancy Luria is education and visitor services unit leader for the National Arboretum.