Birds travel south for the winter, while plants have to deal with the weather where they are. But a few lucky plants took the bus south this year.

The traveling plants were part of the Bus Roots project, which started in New York last year. But when it got too cold for vegetation in the Big Apple, the verdant vehicle, known as the BioBus, made for the sunny south, project designer Marco Castro told Discovery News.

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Bus Roots turned one bus into a mobile green space in the concrete jungle, but there is room to grow. New York alone has an estimated 35 acres (1.4 km2) of bus real estate atop the city's 4500 buses, according to a Bus Roots info packet.

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The garden is made from an aluminum frame with Tyvek, a strong, tear-resistant synthetic fabric, that supports the plants, which sink roots into similar textiles used in the green roofing industry. The system, covering 340 ft2 (32 m2) and weighing approximately 355 lbs. (161 kilograms), only adds the equivalent weight of about two average adult male riders.

“The experiment on the BioBus has not shown any change on gas mileage,” said Castro in an email.

The freewheeling flora are made up of hardy stonecrops (Sedum species) frequently planted on green roofs, and other low maintenance veggies such as lettuce and zucchini.

“So far, the Bus Roots gardens are designed to live mostly on rain, with the occasional watering in case of drought,” said Castro.

Besides adding life to drab city buses, the Bus Root project hopes to provide a source of fresh veggies in urban food deserts, absorb carbon dioxide, insulate the buses from summer heat, suck up storm water, and provide a connection to nature for city-dwellers.

“I would love to expand and experiment with other buses in other cities,” said Castro.

IMAGES:

The BioBus, part of the Bus Roots projects (Shane Ramkinssoon)

The BioBus pick up passengers in New York (Shane Ramkinssoon)

A close-up of Sedum in the Bus Roots garden (Bus Roots info packet)