In Paul Busse’s fairy-tale world, the buildings of New York are ornate, earth-toned, glossy and fashioned from the detritus of the plant kingdom.

Over the past 24 years, Busse and his team of artists have crafted more than 150 landmarks using seed pods, dried eucalyptus leaves, walnuts, bamboo, grape tendrils, fungus, cinnamon sticks — anything that is organic, stable and of utility in the universe of what he calls botanical architecture.

Lady Liberty is a swirl of palm leaves; the Brooklyn Bridge is formed from willow sticks and elm bark; the circular Guggenheim Museum is fabricated from toadstools. But a simple description of these plant-based models is doomed to inadequacy.

Perhaps it’s the warm, subdued colors, or the slightly crooked roof lines, or the interior lights shining through the sallow, resinous window panes, but the feeling is one of cozy enchantment. “Make it whimsical,” Busse said. “Put magic behind it.”

Large model trains weave through the spaces, on trestles above your head or within a sea of moss at your feet. Classic mid-century diesel-electrics, steam locomotives, 19th-century puffers, modern freight trains all animate the conservatory galleries over a total of one-third of a mile of track. The air is filled with the simulated sounds of the railroad.

Occupying much of the New York Botanical Garden’s Haupt Conservatory, the Holiday Train Show has become one of the city’s most popular attractions during the manic holiday carnival between Thanksgiving and New Year’s. Away from the festive bedlam of Broadway, the Fifth Avenue window displays and the rocking Radio City Music Hall, the botanical garden in the Bronx is a little less crazy but far from placid.

Before the show ends Jan. 18, organizers expect to beat last year’s figure of 250,000 visitors, with numbers stoked by a large expansion of the exhibit and related sideshows that include ice sculpting, cocktail nights and readings by the poet Billy Collins.

This is in contrast to the ghost of Christmas Past, when even major botanical gardens such as this one were hard-pressed to huddle visitors around a Christmas tree outdoors and assembled poinsettias inside the greenhouse.

“Most botanical gardens hoped people would come and see some wonderful collections of traditional plants and wander around our beautiful landscapes in the middle of winter but weren’t surprised when they didn’t,” said Todd Forrest, vice president for horticulture and living collections.

When Busse and his zany buildings and oversized trains hit the scene in the 1990s, many botanical gardens were unsure about incorporating them into their holiday events, fearing that they were too far removed from their plant-focused mission. Forrest called the New York Botanical Garden’s first show “a huge gamble.”

Paul Busse started creating his holiday train shows and botanical architecture in the 1990s. (New York Botanical Garden)

The structures are created from an array of natural materials. The Statue of Liberty’s toga is made of palm leaves. The torch is made from part of a pomegranate and dried flower petals. (Adrian Higgins/The Washington Post)

Busse, a soft-spoken Midwesterner with a full beard and suspenders bearing railroad tracks, may not have come across as the prophet he turned out to be. But botanical gardens that have used his services have experienced a large increase in attendance, and his shows are the core of holiday attractions whose success was unimaginable a generation ago.

These venues extend to the U.S. Botanic Garden on the eastern end of the Mall, whose show this year runs from Nov. 26 until Jan. 3 and is themed around garden pollinators. The exhibition includes more than a dozen of Washington’s landmark buildings, including the Capitol, the Jefferson and Lincoln memorials, the Smithsonian Castle, and the locale of the show, the botanic garden’s conservatory at 100 Maryland Ave. SW.

Other institutions with shows by Busse’s company, Applied Imagination, include the Chicago Botanic Garden, the Krohn Conservatory in Cincinnati, the Morris Arboretum in Philadelphia, the Royal Botanical Gardens in Ontario and the Franklin Park Conservatory in Columbus, Ohio.

But it is in the New York Botanical Garden that the artistry is taken to its limits. If you measure its exhibitions by daily attendance, the Holiday Train Show is the institution’s most popular event.

This year, the planners attached two large event tents, one for queueing visitors, the other to accommodate a 3,000-square-foot expansion of the show. It features an elevated train circuit, a central display crowned with a replica of the original Penn Station, and a facsimile of the Haupt Conservatory, itself a New York landmark dating from 1902.

Ironically, this largest-ever show is the first time that Busse, 67, has not been on hand to direct the installation. Coping with Parkinson’s disease, he still conceives track layouts but consigns the execution to his staff. He has not crafted a building in several years.

His 15-member team is divided into architecture artists and those who construct the larger scenes and the railroad infrastructure. Trestles are fashioned from the straight branches of ditch willow, the rock faces and escarpments from sheets of red cedar bark.

The wellspring of this fantasy is Busse’s 12-acre wooded property in Alexandria, Ky., where he lives and established his workshop. Some of the plant material for the buildings is tropical and must be purchased, but about half is simply foraged from the land. He also has planted contorted willows, winged euonymus and other eccentric shrubs to provide material.

During installation, Karen Daubmann, associate vice president of exhibitions at the New York Botanical Garden, examines the model of the Haupt Conservatory, where the Holiday Train Show is staged. (Adrian Higgins/The Washington Post)

The organic buildings have become more refined over the years, and some, like the model of the Haupt Conservatory, have been remade with more crispness. The artists work from blueprints, and a single building can take hundreds of hours to make. Busse’s artists understand his aesthetic: Exact replication is avoided in favor of reducing some features and exaggerating others. The resulting caricature provides the magic.

Viewers “first respond to textures and colors, and they are surprised to see that it’s made out of plant material,” Busse said in a telephone interview.

One of the best examples is the version of the New York Public Library, where visitors will find friezes made from sliced cinnamon sticks, fountain basins crafted from gourds sawed in half, and, perhaps most ingenious of all, working lanterns made from acorn cups and aberrant tree growths called galls. The library's famous lions were created from the seed capsules of a mahogany tree, meadow grasses, grape tendrils and, for the eyes, the seeds of an okra plant. The building was made by Elizabeth Laskey, one of Busse’s artists.

The Statue of Liberty’s torch is made from part of a pomegranate and the dried petals of a flower. The Chrysler Building is fashioned, in part, from ginkgo leaves and pine cone scales. The Empire State Building is crowned with a lotus pod.

It was this inventive use of plant material that persuaded heads of botanical gardens to go with Busse’s train shows.

“The only way this would have been all right in the early 1990s was if it was some way connected to the garden’s mission,” Forrest said. “It would have to reveal something about plants.”

The train shows, in turn, became the inspiration for other exhibitions that reached outside the strict purview of horticulture, including the recently concluded Frida Kahlo show in New York, which focused on her botanical artworks and drew 525,000 visitors over six months.

At the Morris Arboretum, where the outdoor holiday show is a recast version of a summer display, the arrival of the trains “has been transformative for the arboretum,” said Paul Meyer, the director. In the first year, the number of annual visitors jumped from about 30,000 to 70,000 and now stands at 130,000, he said. Other factors have helped, “but the garden railway continues to be a very important draw for the arboretum.”

A replica of the Brooklyn Bridge is made from willow sticks and elm bark. (Ben Hider)

A replica of the original Penn Station, demolished in the 1960s, is one of the largest models in the show, which features existing and lost New York landmarks. (Ben Hider)

More than the numbers, the train shows have a way of reaching across generations and exposing children to the world of plants and gardens. “Kids want to go to the arboretum, and 30 years ago, that didn’t happen,” Meyer said. “Many of us in public gardens are doing what we can to attract kids, to get them outdoors and to connect to nature. We need hooks to draw people in.”

Thirty years ago, Busse had no idea that his dreams would resonate with millions. He was a young, struggling landscape architect. He recalls three episodes that helped launch his enterprise. One was the importation of German-made G-scale trains, which he discovered in a hobby shop in Baltimore in the 1970s. The set was a pricey $175, he remembers. “I think I had $180 in my pocket, and enough gas to make it home.”

The second was an invitation to set up a train display at the Ohio State Fair in the early 1980s. “I was scraping every penny to make it happen and sleeping in a sleeping bag.”

The third was when he was invited to create a display at the Krohn Conservatory, where he was determined not to use cheap plastic buildings and instead fashion his own from natural materials.

“From there, it blossomed into all of this,” said Leslie Salka, Applied Imagination’s director, as she managed the New York installation.

“I had no idea” that it would become so big, Busse said. “But that was always my bottom line, a company that builds happiness. We’re really selling lots of smiles.”