It's summertime and the Lake Forest area is full of colorful plants! It can be tricky to identify when non-native species are invading our property when they look so pretty! At Pizzo & Associates, Ltd., it's our job to make sure the community notices when invasive weeds are stealing space, light, and nutrients from our beloved native species. The battle against invasive weeds never ends, but we are up to the challenge! Below is a selection of species that bloom during the summertime and might be tricking you into thinking they are harmless wildflowers.


6 Summertime Weeds That Are Commonly Mistaken for Wildflowers

Poison Hemlock - Conium maculatum

Poison Hemlock growing in Milwaukee, WI.

Poison Hemlock, a biennial, is currently blooming with clusters of flat-topped white flowers atop tall purple-blotched stems. A member of the parsley/carrot family, it has lacy compound leaves. A single plant may form upwards of 38,000 seeds in its second year. This potently poisonous plant is often deadly if ingested. It is notorious for being the plant that was used to poison and kill Socrates. Another invasive species, Wild Chervil (Anthriscus sylvestris) is nearly identical, and is becoming more common in our area.

Teasel - Dipsacus fullonum and Dipsacus laciniatus

Teasel weeds growing in Winnetka, IL.

Both of our local Teasel species are invasive biennials that bloom in the summertime along roadsides and fields. Their leaves are large, coarse, and spiny, clasping the stem to form a cup where water collects, allowing mosquitoes to breed. Prickly flower heads appear in summer above needle-tipped, spiny bracts. The flowers then dry into a semi-cylindrical seed head and form up to 34,000 seeds per plant. It will readily reseed if mowed in the fall and can form dense colonies that choke out native seedlings.

Birdsfoot Trefoil - Lotus corniculatus

Birdsfoot Trefoil weeds in Lake Forest, IL.

This low-growing legume has brilliant yellow pea-like flowers above three-lobed leaves. It thrives in disturbed areas and untreated turf, forming a deep root mass and dense, spreading mats of foliage that crowd out native species. It also spreads by seed, generating about 5,000 seeds per plant. Fire increases its germination, it can tolerate mowing, and it is not very susceptible to some herbicides. These attributes make it particularly tough to control.

Purple Loosestrife - Lythrum salicaria

Purple loosestrife weed found in Lake Genova, WI.

Purple Loosestrife is commonly found invading wetlands, retention ponds, roadside swales, and ditches. It can get up to six feet high and has a flower spike of pinkish-purple blossoms. Purple Loosestrife will aggressively form colonies, crowding out your native plants. A single mature flower stalk can produce up to 300,000 seeds. Purple Loosestrife spreads readily by seed and can regenerate from root fragments. It was brought to the U.S. as an ornamental garden plant by Europeans. There are some loosestrife-eating insects available, but they cannot completely control the plant.

Wild Parsnip - Pastinaca sativa

Wild parsnip weeds with a ladybug found in New Buffalo, MI.

Wild Parsnip invades natural areas, disturbed sites, and roadsides. Its 2-3'-tall stalks bloom with flat-topped, bright yellow flower clusters. Wild Parsnip is usually a biennial with a rosette of ferny leaves the first year and a four-foot-high hollow grooved flower stalk the second. Flat oval seeds follow the clusters of blossoms. At first glance, it resembles a yellow version of Queen Anne’s Lace. Be careful when handling Wild Parsnip! When its juice comes in contact with skin, it may cause a severe rash or burn. Some notable examples of this effect have ended with hospital stays in recent years.

Red Clover - Trifolium pratense

Red clover weeds found in Ogden Dunes, IN.

The round, pink-magenta flower heads of Red Clover bloom above its bushy, three-leaved foliage. Each leaflet is marked with a pale green chevron or “V.” It has a fibrous root system and stems will root at the nodes when in contact with soil, allowing it to colonize an area quickly. Red Clover is commonly found in fields and meadows, but readily invades natural areas and native landscapes. This plant tends to be between 8 and 20 inches high.


We are your natural land restoration and maintenance company.

Since 1988, our team at Pizzo & Associates, Ltd. has restored and maintained the woods, prairies, and wetlands around the Lake Forest, Barrington, and Naperville communities. We have the experience and training to quickly identify and control tricky invasive weeds that masquerade as beautiful wildflowers. Getting rid of invasive species like the ones above will save our native plants and invite wildlife like birds and butterflies to reap the benefits of a functioning native plant ecosystem. Call our office today at (815) 495-2300 to learn more about our restoration and maintenance efforts.