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Some Weeds Bad Side Outweigh the Benefits

May Berenbaum, University of Illinois entomologist and researcher of the decline in honeybees, has said Illinoisans need to be more accepting of weeds, which provide habitat and food sources for honeybees and beyond.

But flowering weed patches and prairie remnants contain a few weeds that behave very badly despite the contributions they may provide: ragweed, teasel, poison ivy and garlic mustard claims University of Illinois Horticulture Educator, Kelly Allsup.

Ragweed is a native annual that grows up to 3 to 4 feet tall and has deeply incised leaves with cylindrical flowers at this time of year. It's commonly found along road edges, in disturbed soils and along field perimeters. Male plants produce lots of pollen that is carried by wind to female flowers. A prolific producer of seed, ragweed also inhibits growth and development of neighboring plants. Despite its contribution to providing pollen and nectar to birds, bees and moths, it behaves badly because it assaults allergy suffers like me.

Common and cut leaf teasel lines the roadsides with spiky silvery flowers. The plants are prickly all over, especially along the midribs of the leaves. Teasel is a biennial that forms more than 2,000 seeds. Despite being planted in the 1700s for use in cloth production, teasel plants that are not controlled can choke out prairies and wildflower gardens.

Poison ivy can vary in plant characteristics, but the leaves come in threes and are alternately arranged on the plant. The green leaves turn red in the fall and can become a woody vine growing up in the trees. If you are driving to Sugar Grove Nature Center, you may see the brilliant scarlet leaves decorating the trunks of trees. Virginia creeper has brilliant fall color like poison ivy, but has five leaflets. Though the berries are a food source for 33 species of birds, human contact with leaves, stems, roots, flowers and berries can cause intense blistering and rashes.

Garlic mustard is a biennial that has kidney-shaped leaves in its first year and produces white flowers on top of alternating triangular and toothed leaves. Garlic mustard smells heavily of garlic in the early season and can be identified by the slender white root. Despite being planted for culinary use by early settlers, this non-native dominates forest floors.