CHICAGO (CBS) — The Garfield Park Conservatory has lost one of its rare plants.

WBBM Newsradio’s Nancy Harty reports, at roughly 20 feet tall, it was the largest double coconut palm living in a greenhouse. It had been at the conservatory’s Palm House for 45 years, according to the Chicago Park District.

Director of Conservatories Mary Eysenbach said they’ve known for more than a year that the tropical plant was struggling, but only last week finally cut off the last leaf.

LISTEN: WBBM Newsradio’s Nancy Harty reports

“We’ve left the actual trunk; on the crazy, hopeful, off-chance that another leaf might come out of it,” she said.

Staffers tested the plant for toxicity, pathogen and nutrient problems and found nothing. Eysenbach said it would be virtually impossible to grow a new double coconut palm, because its native country, the Seychelles Islands, is a World Heritage Site.

“They have restricted the export of the seeds because it’s such a rare plant,” she said.

Horticulturist Robert Van Tress bought a double coconut palm seed in Ceylon in 1960 and tried to cultivate the plant, but failed, according to the park district. After he retired in 1967, his colleagues tried to cultivate another plant by buying a new seed, digging a six-foot silo, and lining it with lead coil to maintain the 80 degree temperature needed for the seed to grow.

The plant thrived and became too tall for its original location on the southern end of the Palm House and, when the roof was renovated in 2003, the tree was moved to a spot with a higher roof.