The Morton Arboretum in Lisle is in the midst of the biggest changes in its 81-year history. By 2005, it will have spent $43 million on improvements to its 17-hundred-acre park. Those include installing new visitor amenities aimed at boosting annual attendance from 450,000 to 750,000.

And the Chicago Botanic Garden in Glencoe is in its third year of a $100 million makeover as it seeks to increase attendance from 750,000 to 1 million annually.

The two public gardens are following the lead of zoos and major indoor museums that have experienced a popularity boom in the last 20 years through expansion and innovative exhibits.