The Homeowners Column

The Homeowners Column

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Exotic Plants Added to Illegal List

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Sandra Mason
State Master Gardener Coordinator

A gardener's goal is to help plants thrive. But some plants prosper a bit too well and quickly move from treasured acquisition to scorned trespasser. Weeds are "plants out of place", whether they came with a price tag or not.

Unfortunately some plants grow well beyond our backyard borders and result in threatening native plants and animals in our forests, prairies and natural areas. You think you have weed problems, just try weeding hundreds of acres of woodland. In addition they supernaturally appear in our landscapes to defy our quest for excellence. As we select what plants to grow this year and plan for editing our existing plants, look beyond a plant's beauty and make sure it is not on the list of illegal wicked weeds.

One effective way to keep these space invaders at bay is by preventing their spread through official regulation. In 2015 sixteen species were added to the Illinois Exotic Weed Act for a total of twenty six regulated exotic species in Illinois.

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."

As the act reads: "It shall be unlawful for any person, corporation ... 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. This law does not regulate possession nor does it require existing plants to be removed, although as responsible gardeners we should eradicate them. Since this Act is limited to Illinois, these plants may be available for purchase in other states. The fine print in catalogs will state "not for sale to residents of Illinois".

As of 2015 the illegal exotic plants often listed as ornamentals are: Oriental bittersweet (Celastrus orbiculatus); Russian olive (Elaeagnus angustifolia); Autumn olive (Elaeagnus umbellata); Thorny olive (Elaeagnus pungens); Japanese knotweed (Fallopia japonica); Giant knotweed (Fallopia sachalinensis); Bohemian knotweed (Fallopia xbohemica); Lesser celandine (Ficaria verna); Japanese honeysuckle including the cultivar 'Hall's' (Lonicera japonica) [pictured above], Amur honeysuckle (Lonicera maackii) [pictured below]; Spring honeysuckle (Lonicera fragrantissima); Morrow's honeysuckle (Lonicera morrowii); Tatarian honeysuckle (Lonicera tatarica); Multiflora rose (Rosa multiflora); Purple loosestrife (Lythrum salicaria); Kudzu (Pueraria lobata); Saltcedar (all Tamarix species); Saw-toothed buckthorn (Rhamnus arguta); Common buckthorn (R. cathartica); Dahurian buckthorn (R. davurica); Japanese buckthorn (R. japonica); Glossy buckthorn (R. frangula including cultivar Fine Line®) and Chinese buckthorn (R. utilis).

Additional plants on the list are not typically seen for sale as ornamentals: Poison hemlock (Conium maculatum); Teasel (all Dipsacus species) and Giant hogweed (Heracleum mantegazzianum).

The severity of a plant's invasiveness depends on an area's soil and environmental conditions. Some plants are invasive in other parts of the country, but are not commonly invasive here, at least not yet. So we must remain observant. If a garden plant is popping up all over your garden and yard, a red flag should unfurl and smack you in the face declaring this plant has no boundaries. A plant with the way and the will to go beyond your garden into natural areas.

For more information or Headwaters Invasive Plant Partnership (HIPP) or contact us for University of Illinois Extension Forestry Bulletin. "Invasive Plant Species Regulated by the Illinois Exotic Weed Act" which details plant descriptions.

Join Mike Davis of the Champaign Park District and me on Monday March 21, 2016 at 6:30pm at UI Extension auditorium 801 North Country Fair Drive Champaign, IL for our program Invasive Plants in your landscape? What to Do. Topics: Identifying and managing common invasive plants and replacing invasive plants with good alternatives. No fee, but please register 217.333.7672.

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