By John Woodmansee
Agriculture/Natural Resources Extension Educator, Purdue Extension Whitley County

COLUMBIA CITY — It’s been around since 2020, but did you know that in Indiana, there is a list of 44 plants that are illegal to sell, gift, barter, exchange, distribute, transport, or introduce without a permit? The Indiana Terrestrial Plant Rule has been around for five years now, but many may still be unaware that the rule exists.

John Woodmansee

Retailers are well aware of the rule. But, as the rule states, this regulation includes anyone wanting to sell, gift, barter, exchange, distribute, transport, or introduce certain plants in Indiana. Find the full text of 312 IAC 18-3-25 at iar.iga.in.gov/code/2026/312/18.

The rule was written to address and mitigate the impacts of invasive species, including loss of biodiversity, degradation of natural habitats, negative effects on property values, decreased agricultural yields, and negative impacts on public utilities, recreation and tourism.

Besides the reasons just stated, it’s also important because millions of dollars are spent annually to control invasive species. Invasive species are plants that are alien (not native to Indiana) and cause harm to the environment or human health.

The state legislature established the Indiana Invasive Species Council to enhance the ability of government agencies to detect, prevent, monitor, and manage new and long-established invasions, as well as increase public awareness about invasive species. IISC conducts extensive research to document the effects of invasive species and determine which ones pose the greatest threats.

Examples of plants in the rule include garlic mustard, bush honeysuckles, autumn olive, Japanese honeysuckle, Japanese knotweed, poison hemlock, white mulberry, blunt-leaved privet, and tree-of-heaven.

Several other weed species, such as multiflora rose, purple loosestrife, and Canada thistle, are regulated under other laws. Learn about noxious weeds in the Purdue Extension publication “Noxious and Invasive Weeds and the Weed Laws in Indiana.”

Find information from Indiana DNR on the Indiana Terrestrial Plant Rule here.