A showcase of old-style poinsettias is among the highlights of the “Seasons Greenings” exhibit at the U.S. Botanic Gardens in Washington, which continues through January 5. (Jerry Hagstrom/The Hagstrom Report)    Left: Poinsettias highlight a model of the Washington Monument on display in the Garden Court at the U.S. Botanic Garden. Right: The Lincoln Memorial is another of the capital’s landmark buildings that has been replicated using natural materials. (Jerry Hagstrom/The Hagstrom Report)
A pair of topiary bears set off a model of the U.S. Botanic Garden building itself. (Jerry Hagstrom/The Hagstrom Report)
The ”World’s Fair” fantasy train display features structures that resulted from the nation’s long history of public exhibitions. This is a model of the tower — known as the “Space Needle” — created for the 1962 Seattle World’s Fair. (Jerry Hagstrom/The Hagstrom Report)

The U.S. Botanic Garden, at the foot of the House of Representatives, is holding its annual poinsettia showcase and other holiday displays. It is open 10 a.m. to 5 p.m. daily, in December it is open Tuesdays and Thursdays until 8 p.m., with music concerts scheduled on those nights.

Established by Congress in 1820 and administered through the Architect of the Capitol since 1934, the Botanic Garden has a special exhibit on the development of the poinsettia, the red flower brought to the United States from Mexico by Joel Roberts Poinsett, the first U.S. minister to Mexico, who sent samples of the plant back to the United States in the late 1820s.

The display includes examples of the early poinsettias, which are described as a “short lived, but distinctive red cut flower” and the varieties introduced in the 1960s that are bushy and mass-marketed today. There are also examples of the new colors developed through radiation begun in the 1980s.

Mixed in with the poinsettias are models of many Washington landmarks and models of World’s Fair structures. A fantasy train runs on 800 feet of track through an “enchanted forest.”

The holiday will be featured through January 5. The Botanic Garden’s website has a listing of the concerts.

• U.S. Botanic Garden — Season’s Greenings