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The Homeowners Column
Illegal Weedy Garden Plants
Extension Educator, Horticulture
As gardeners we all have regrets. Some more earth-shattering and earth-scattering than others: "I wish I bought that plant when I saw it in the nursery". "Maybe I should have left my credit card at home". "I wish I had never planted that wickedly evil, completely vile plant".
As we select what plants to grow this year, there are a few plants that cannot be legally grown in Illinois. It's not just ragweed, Canadian thistle or marijuana. There are other illegal plants perhaps not as well known that are listed in the Illinois Exotic Weed Act.
Within the Act the definition of exotic weeds are: "…plants not native to North America which when planted either spread vegetatively or naturalize and degrade natural communities, reduce the value of fish and wildlife habitat or threaten an Illinois endangered or threatened species."
Legally designated Exotic Weeds are: Japanese honeysuckle including the cultivar 'Hall's' (Lonicera japonica), multiflora rose (Rosa multiflora), purple loosestrife (Lythrum salicaria), kudzu (Pueraria lobata) and several species of buckthorn (Rhamnus spp.).
In my mind there are numerous worthy candidates for additions to the list such as bush honeysuckle and garlic mustard. A great deal of time and resources are spent trying to eradicate these nasties from local woodlands before they choke out all our beloved wildflowers. You think you have weed problems, just try weeding a 600-acre woodland.
As the act reads: "It shall be unlawful for any person, corporation, political subdivision, agency or department of the State to buy, sell, offer for sale, distribute or plant seeds, plants or plant parts of exotic weeds without a permit issued by the Department of Natural Resources."
In other words, don't buy, sell or plant these plants and don't give them to your friends or enemies. Since this Act is limited to Illinois, these plants may be available for purchase in other states. You may have noticed the fine print with some plants in catalogs "not for sale to residents of Illinois".
Some of the exotic weeds started out as garden plants. For instance, purple loosestrife is a very pretty plant with a spike of pink flowers all summer long. The problem is the loosestrife doesn't know when to quit or how to be a good neighbor. Although pretty, it is ecologically ugly as it proceeds to conquer the garden and the local natural areas and waterways by choking out native plants vital for wildlife food and shelter.
The following are Purple Loosestrife cultivars (cultivated varieties) which are illegal to sell or plant: 'Happy,' 'Robert,' 'Firecandle,' 'Brightness,' 'The Beacon,' 'Lady Sackville,' 'Atropurpureum,' L. s. roseum superbum, and L. s. tomentosum.
Some cultivars are listed as legal in Illinois since they are derived from a different species of loosestrife, Lythrum virgatum; however, a wealth of research is showing these cultivars are not as harmless as once thought. Supposedly the seeds are sterile and will not reseed. Research has shown the pollen is viable and will pollinate the weedy species.
Rather than worrying about which loosestrife is correct, why not try some beautiful alternatives such as blazing star (Liatris), dragonshead, (Physostegia), Veronica 'Barcorolle,' Salvia 'Amethyst' or 'Rose Queen,' or 'Fascination' Culver's root (Veronicastrum). They are all perennial plants with beautiful spike flowers minus the nasty weediness.
Being a devoted plant collector it is difficult for me to leave out something as beautiful as purple loosestrife. However when I realize the consequences, it becomes very easy to feed my compost pile with purple loosestrife. Legal or not, we all must be responsible gardeners when it comes to plant selection.
Monday, February 21, 6:30 PM Eco-conscious Gardening and Landscaping. Discover native plants for landscaping and choosing plants to avoid ecological problems. UI Extension 801 North Country Fair Drive Champaign. PH: 217-333-7672.