IT LIES ALONG THE RAW REACHES OF NEW YORK AVENUE NE, ON the way out of town, between the old United Clay Products brickyard and the sleepy Anacostia River. No wonder, then, that 60 years after its creation by an act of Congress, the National Arboretum remains the least known of Washington's museums. Sure, it gets almost a million visitors a year, but that's only a fifth of what the Smithsonian Air & Space Museum gets, and most arboretum visitors think about the place only in late April, when 70,000 azaleas announce spring's arrival inside the Beltway.

Azaleas may virtually demand attention, but for most trees and plants, growing, blooming and going dormant are quiet, almost private, activities, offering subtler pleasures the year round. Drive through the arboretum now, in one of the humbler periods of the year, and the mandated 15 miles an hour may not seem fast enough. The open areas, after all, are just open areas, the perennials and the flowering shrubs lying dormant. But give yourself over to nature's decidedly slower pace and more muted palette, and you'll find wonderment everywhere.

Just as seasonal changes call for an adjustment of expectations, so does the constant change of scale. You have to close down your peripheral vision in order to enter the miniature world of the gnarled 112-year-old needle juniper from Japan, in the National Bonsai Collection. But this spring you'll want to open your eyes wide to take in the sweep of lawn that will be the permanent home of the 24 columns of the original east front of the U.S. Capitol. Yes, there's glory in the large and the small here: The giant oaks of Fern Valley are magnificent, but so are the miniature daffodils at their base.

The darker side of life intrudes, of course. That dwarfed needle juniper has been stolen -- twice. And the arboretum's idyllic ponds have claimed at least two drowning victims. Nature commits its own violence, like the brutal winter of 1977, which killed off most of the delicate camellias. Nor is the arboretum immune from politics. Its parent agency, the Department of Agriculture, was for a long time accused of being indifferent to the arboretum's development needs. And its 444 acres have sometimes looked tasty: to the District government, which in 1969 wanted to use the land for low-income housing, and to the late, irrepressible Martha Mitchell, who in 1970 suggested that Cabinet families be housed on the grounds.

But, mostly, the arboretum just goes on from season to season, growing, blooming, going dormant. Even the official scientific work that is done here -- public education and developing pest- and disease-resistant plants -- must follow nature's slow, cyclical course. We asked photographer Nathan Farb, whose books of photographs include The Adirondacks (Rizzoli, 1985) and The Russians (Barrons, 1977), to visit the arboretum over the course of 1986-87. His record of that 12-month period tells the story of a part of Washington that many glance at but few see, that experiences constant change but never changes.