United States National Arboretum
Just off New York Ave. as I drive into Washington D.C. is an island of green completely surrounded by a 10 foot high wrought iron fence. Happily there is a big gate and it is open from 9 to 5. Inside are about 450 acres of beauty and science and a bit of retail.
Collections of plants are maintained in clustered areas so one can compare within a given collection species X to species Y. There are boxwood, crab apple, holly, azalea, conifer, dogwood, magnolia, antique rose, perennial, fern, native plant, and herb collections that one can walk through, sit by and observe. There is also a gorgeous bonsai and viewing stone display, a huge Koi pond with aquatic plants, a youth garden, many creeks and ponds and about 10 miles of little roads plus paths for a slow drives, biking or walking. There is also a trolley bus for a relaxed ride around the campus.
The science part comes in with the plant introduction program. From their web page: “Many of the ornamental and flowering trees and shrubs and herbaceous garden plants found in cities, towns, and home landscapes throughout the United States and many other countries were developed by scientists at the U. S. National Arboretum through years of hybridization, selection, and careful evaluation. During its 70 year history, the Arboretum has released over 650 different woody and herbaceous plants to the American public through the nursery and floral industries. Each year, several new plants are made available.”
The retail portion includes a tiny little gift shop that never fails to please. Whoever is in charge of purchasing has such a talent for “cool things”. They have great books, garden themed toys and jewelry, unique flower arranging and garden tools. There is also an annual plant sale sponsored by FONA (Friends of the National Arboretum) where members can sometimes pick up newly introduced plants years before they make it into commercial production.
Educational programs occur several times a week, most are free. I love this place.
The web page is also high quality with lots of content on introduced plants, great photos, maps, events lists, what's blooming lists, gardening information:
http://www.usna.usda.gov