Better look again, the Field Museum's botanical beauties are fake

Up the steps from the museum's Gorgosaurus dinosaur, next door to the Chinese jades, is a collection of - well, fakes. They are exquisitely rendered. Reportedly, they have fooled experts.

Nevertheless, late last month and with some fanfare, Chicago's venerable Field Museum of Natural History reopened its exhibit of 300 lush and leafy forgeries.

''Everything is illusion,'' announced one museum official gleefully at a reception for the press. He was referring to the museum's newly refurbished exhibit of plant models, called Plants of the World. The display is the largest collection of its kind in the world.

Why, it may be asked, should a museum show fake plants to the public?

First, they are not just ''something you buy at Woolco,'' says Michael Dillon , an assistant curator in charge of the exhibit.

The models are meticulous copies of plants, right down to their yellowing leaves, insect holes, and dirty roots. Examples of nearly one-third of all plant families are displayed. Botany students could learn much here, professors say, and so could the public.

While museums have successfully introduced the public to geology and zoology through displays of rocks and mounted animals, botany has generally been ignored , Dr. Dillon says. How, after all, do you build a permanent exhibit of plants at a reasonable price, when the live specimens thrive in such diverse conditions as the Rocky Mountains and Africa's Namib Desert?

The models have solved all that. And the exhibit comes none too soon, botanists say.

Every minute, more than 35 acres of the world's tropical and subtropical forests are destroyed by logging and clearing of land for agriculture, primarily in South America, according to the museum.

cho The vegetation is being destroyed ''before we have any idea of what's really there,'' says Dr. Luretta Spiess, senior research associate in botany at Northwestern University in Evanston, Ill. ''Anything that can bring people's attention to this is important.''

''We're living in a world where the number of plant specimens is declining at a fierce rate,'' says Manfred Ruddat, editor of Botanical Gazette, published by the University of Chicago Press. ''It's a very difficult thing to do to get the public hot under the collar about plants. . . . (But) plants are the beginning of the food chain. Without plants there would be no life on earth.''

The Field Museum's efforts in botanical education are not new.

In 1909, the first curator of botany hired an accomplished denturemaker to build plant models. Museum employees were sent all over the world to collect specimens. Black-and-white photographs, watercolor paintings, extensive notes, and plaster of Paris molds were made of the plants. Sometimes, preserved specimens were sent back to the laboratory.

The model building was a painstaking process, too, using latex, glass, wire, and waxes. Plastics also were used in later years, until the project came to an end in 1968.

''These people were artists, really,'' Dillon says. ''It's this kind of extreme attention to detail that I question whether we'll ever see again.''