70 ILCS 830/1
The corporate authorities of forest preserve districts containing a population of 100,000 or more located in counties of less than 3,000,000 inhabitants are authorized, on land now or hereafter under the control of such forest preserve districts, to prepare and maintain grounds for a botanic garden, to acquire, plant, maintain and display botanic material, to conduct research for improvement of plant species and for plant protection against disease and harmful insects, for the general care and growing of plant material, and to erect and maintain such structures appropriate for the purposes aforesaid; or such corporate authorities may authorize the directors or trustees of any botanic garden existing and organized under the laws of Illinois, to maintain a botanic garden as aforesaid out of funds belonging to said botanic garden; or the corporate authorities of such forest preserve districts may contract with a botanic garden or horticultural society organized and existing under the nonprofit laws of Illinois to establish and maintain a botanic garden as aforesaid, within such forest preserve districts, out of the tax provided in this Act.
70 ILCS 830/1