U.S. Botanic Garden staff member waters plants that are part of the garden’s holiday display, which opens Thursday. The Capitol and other structures are made entirely from plant material. (Bill O'Leary/The Washington Post)

A bold horse named Cincinnati stands on a marble platform in front of the U.S. Capitol. His mane and tail blow in a cold breeze on an overcast November morning. The bronze horse and his rider (Civil War General Ulysses S. Grant) have weathered to a noble dark green.

Across the street, inside the U.S. Botanic Garden (USBG), stands a small replica of the horse and rider, in front of a replica of the Capitol. They are part of the museum’s annual holiday display. The moist, warm indoor air smells of cedar and flowers. The little horse’s head — poking out from a bed of poinsettias — looks like it’s made from the shell of a pistachio nut.

A Thomas the Tank Engine is one of the six trains that wind their way around the exhibit. (Bill O'Leary/The Washington Post)
All in the details

Every year, the USBG puts on a fantastic holiday display of trains, live plants and replicas of landmarks from Washington and other places. The replicas are made of dried plant materials, such as bamboo stalks, pine cones, leaves from beech and sycamore trees, shell fungus, reeds, twisted vines and delicate grape tendrils.

The seven-foot-long Capitol replica, the first one visitors will see when they walk in, took more than 500 hours to build. Its windows are made with cinnamon curls, pine cone scales and wheat. “You might think it’s just a really neat model,” says USBG spokesman Ray Mims, “then you realize — ‘Hey, that frieze [a sculpted decoration] on the front is made from corn husk, and the chandelier on the portico is an acorn.’ ”

Before the holiday display opens to visitors, staff horticulturalists bustle around the conservatory, watering plants, putting on final touches and making sure the fog machine works. Staff and volunteers sort through huge boxes of glass ornaments to hang on the giant cut Christmas tree.

This year’s display celebrates an 1800s expedition of the world’s oceans, continents and islands. Ships and 33 lighthouses — including several from the Chesapeake Bay — are featured. (Bill O'Leary/The Washington Post)
Re-creating an expedition

In the mid-1800s, the U.S. Congress sent six ships to explore the world’s oceans, continents and islands. Over four years, scientists traveled more than 87,000 miles, collecting live plants and artifacts. These items were among the founding collection of the USBG. Today the museum still has four plants from the expedition.

This year, USBG’s holiday display celebrates that expedition by inviting visitors to take their own journey into a “nautical wonderland.”

On that trip, you might scan the horizon to see a lighthouse or a ship through the fog. You might grab an imaginary telescope and search for details such as the shimmering green scales of the sea serpent train or the tiny canoe made from the seed pod of a butterfly weed.

This year’s exhibit includes replicas of 33 lighthouses (including Sandy Point Shoal and Thomas Point Shoal, both near Annapolis) and a model of the Thomas Viaduct, which stands over the Patapsco River near Baltimore. Blocks of tree bark give the arched replica a stone-built feel.

Throughout the exhibit, live plants create an imaginative backdrop for the ships and lighthouses. Aloe plants look like swimming octopi, Christmas cactuses resemble schools of red fish, and white-streaked leaves suggest choppy seas. Trains toot, holler and whistle around this seascape.

Everyone seems to notice something different. USBG education specialist Lee Coykendall says she sees new details every day. “My hope is that people walk in and feel like they’ve been transported into a really great book or movie,” she says.

Kitson Jazynka

Trains at the U.S. Botanic Garden will travel nearly 3,000 miles before the exhibit closes. (Bill O'Leary/The Washington Post)
Fun facts

•The USBG’s holiday display takes months to set up but years to plan.

•A company called Applied Imagination, founded by landscape architect and artist Paul Busse, created all the replicas and everything made from recycled plant materials.

•On the Coney Island Lighthouse, citrus seeds are used for the lettering.

•The bonsai trees used throughout the display give the lighthouses a weathered, beachy feel and are from the USBG’s Japanese-garden-themed orchid exhibit.

•Diorama-like “portholes” draw attention to treasures such as a little turtle made from a sea pod and a sea horse whose head is made from a peach pit.

By the numbers

●4 miniature fairy gardens.

●6 trains traveling nearly 3,000 miles over the 39 days of the show.

●10 topiary (carved out of a shrub or tree) animals.

●52 genera of plants around the trains in the garden’s East Gallery.

●650 feet of train track.

●2,500 poinsettias.

●7,500 to 10,000 bulbs on the Christmas tree.

●10,000 hours of human labor to pull it all together.

If you go

What: “Season’s Greenings” in the U.S. Botanic Garden’s conservatory.

Where: 100 Maryland Avenue SW.

When: Thursday through January 4. The best times to visit are weekdays early in December or on select Tuesday and Thursday evenings in December when the conservatory is open until 8 p.m.

How much: Free.

For more information: A parent can call 202-225-8333 or visit www.usbg.gov.