Feathery weed with two part seeds

The Only Weed Identification Guide You’ll Ever Need: 33 Common Weedy Plants to Watch For

Don’t let these pesky plants crash your garden party! The first step is to know your enemy. Then you’ll know the best way to deal with your weed problem.

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What is a Weed, Anyway?

A weed can be any plant growing where you don’t want it to. However, there are some particularly weedy species to keep an eye out for. These aggressive plants not only make your yard look messy, they can also choke out the garden plants you’ve worked so hard to grow. Whether you’re trying to identify lawn weeds or garden weeds, this handy guide will help you identify more than 30 common weeds by photo, plus give you tips for how to best remove them.

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Dandelion

Type: Broadleaf perennial

Size: 12 inches tall, 6 – 16 inches wide

Where It Grows: Lawns and gardens in sun or shade

Appearance: This common lawn weed has a long taproot; leaves are deeply notched. Yellow flowers mature into puffballs. Dandelion seeds are like parachutes that fly away in the wind, helping them invade new spaces in lawns and garden beds.

Weed Control Tips: Mulch to prevent dandelions in gardens. Pull dandelion weeds by hand or treat lawns with a broadleaf herbicide, which won’t kill grass.

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Oxalis

Type: Broadleaf perennial

Size: To 20 inches tall

Where It Grows: Sunny or shady landscape, lawn, or garden areas

Appearance: This garden weed has light green leaves that look a little like clover and cup-shape yellow flowers in summer and fall.

Weed Control Tips: Mulch garden areas in spring to prevent weeds. Pull oxalis weeds by hand or spray weeds with a broadleaf herbicide in spring or fall.

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Crabgrass

Type: Grassy annual

Size: To 18 inches tall and 20 inches wide

Where It Grows: Lawn, landscape, and garden areas in sun or shade

Appearance: Crabgrass is exactly what it sounds like: A grassy weed. This lawn weed grows roots anywhere the stem makes soil contact. Seed heads spread out like four fingers.

Control: Use a preemergence weed preventer to prevent seeds from sprouting, pull crabgrass by hand, or spot-treat with a nonselective herbicide if growing in sidewalk cracks or other places where nothing else is growing.

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Bindweed

Type: Broadleaf perennial

Size: Climbs 6 feet or more

Where It Grows: Landscape and garden areas in sun

Appearance: Identify this garden weed by its arrowhead-shape leaves on twining vines. Bindweed also produces white to pale pink morning glory-type flowers.

Control: Mulch your garden to prevent bindweed. Repeatedly pull or cut down growing bindweed plants and/or spot treat with a nonselective herbicide designed to kill roots, not just above-ground growth.

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White Clover

Type: Broadleaf perennial

Size: 8-10 inches tall, 12 inches wide

Where It Grows: Lawn, landscape, and garden areas in sun to partial shade

Appearance: White clover has three-lobe leaves and round white flower clusters. The plants quickly spread outward to form dense mats of foliage.

Control: Mulch your garden beds to prevent white clover in landscape areas. Use an iron-based herbicide to get rid of clover growing in lawns or dig out the weeds in garden beds.

Test Garden Tip: Clover adds nitrogen to the soil plus the flowers feed many pollinators so some gardeners use this plant to create a more environmentally friendly lawn.

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Nutsedge

Type: Grass-like perennial

Size: 2 feet tall, 1 foot wide

Where It Grows: Lawn, landscape, or garden areas in sun or shade

Appearance: Nutsedge has slender, grassy leaves, triangular stems, and small, nutlike tubers on the root system. When these weeds pop up in lawns, they often grow faster than turf grass, so they are easy to spot.

Control: Mulch garden areas in spring to help prevent nutsedge. Plants are easy to pull up by hand, but it will take repeated weeding to get rid of an infestation. Various herbicides are labeled for use on nutsedge in lawns but it is important to use the right one for the type of turf grass you have to avoid damaging it.

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Creeping Charlie

Type: Broadleaf perennial

Size: 4 inches tall, several feet wide

Where It Grows: Shady lawn, landscape, or garden areas

Appearance: Identify this lawn weed and groundcover by its scalloped leaves, creeping stems, and clusters of purple flowers in late spring.

Control: Mulch garden areas in spring to prevent creeping charlie. Pull plants by hand or spray with a postemergence herbicide in spring or fall.

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Lamb’s-Quarter

Type: Broadleaf annual

Size: To 4 feet tall and 18 inches wide

Where It Grows: Landscape and garden areas in sun or shade

Appearance: Lamb’s-quarter’s scalloped, triangular leaves have gray undersides.

Control: Mulch your garden to prevent lamb’s-quarter. Pull weed plants by hand or use a postemergence herbicide.

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Plantain

Type: Broadleaf perennial

Size: To 8 inches tall and 12 inches wide

Where It Grows: Moist lawn and garden areas in sun or shade

Appearance: When you’re identifying weeds in your garden, if you spot broad, flat, oval-shape leaves arranged in a low rosette, you’ve likely found a plantain.

Control: Mulch to prevent plantains growing in the garden. Pull these weeds by hand or use a postemergence herbicide in lawns.

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Dayflower

Type: Annual grass relative

Size: To 30 inches tall and wide

Where It Grows: Sunny or shady landscape areas

Appearance: Dayflowers have dark green leaves sprouting from a stem and brilliant blue flowers through the summer.

Control: Mulch the garden to prevent weeds or use a preemergence herbicide in spring. Pull weeds by hand or spot-treat with a nonselective postemergence herbicide.

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Purslane

Type: Broadleaf annual

Size: To 6 inches tall and 2 feet wide

Where it grows: Dry, sunny landscape and garden areas

Appearance: Identify this weed groundcover by its fleshy, dark green leaves and small yellow flowers at the ends of the stems.

Control: Mulch your garden to prevent purslane or use a preemergence herbicide in the spring. Pull plants by hand or spot-treat with a nonselective postemergence herbicide.

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Velvetleaf

Type: Broadleaf annual

Size: To 6 feet tall and 3 feet wide

Where It Grows: Fertile, sunny landscape and garden areas

Appearance: Velvetleaf gets its name because of its large, velvety heart-shape leaves up to 10 inches across. The weed blooms with yellow flowers in summer.

Weed Control: Mulch your garden to prevent velvetleaf or use a preemergence herbicide in spring. Pull existing plants by hand or use a postemergence herbicide.

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Wild Violet

Type: Broadleaf perennial

Size: 6 inches tall, 6 inches wide

Where It Grows: Shady lawn, landscape, or garden areas

Appearance: Wild violet is a groundcover with heart-shape leaves and purple flowers in late spring.

Control: Mulch garden beds in spring to prevent wild violet. Pull weeds by hand or spray with a postemergence herbicide in spring or fall.

Test Garden Tip: This plant is sometimes grown as an ornamental in shade gardens.

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Smartweed

Type: Broadleaf annual

Size: To 42 inches tall and 30 inches wide

Where It Grows: Sunny landscape and garden areas

Appearance: Identify garden weeds like smartweed by its lance-shape leaves often marked with purple chevrons. It’s an upright plant with pink or white flowers in summer and fall.

Control: To prevent this weed, mulch garden beds in spring. Pull plants by hand or apply a postemergence herbicide once it grows.

Test Garden Tip: This weed is native to areas of North America. Unlike many exotic weeds, it does support local wildlife.

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Quickweed

Type: Broadleaf annual

Size: To 2 feet tall and wide

Where It Grows: Sunny landscape and garden areas

Appearance: Quickweed has jagged, hairy leaves and small white daisy-shape flowers in summer.

Control: Use a mulch or a preemergence herbicide in spring to prevent quickweed. If plants do grow, pull them by hand or spot-treat them with a postemergence herbicide.

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Pigweed

Type: Broadleaf annual

Size: 6 feet tall, 2 feet wide

Where it grows: Sunny landscape or garden areas

Appearance: Pigweeds are tall plants with a taproot. Identify weeds by their hairy-looking clusters of green flowers (though some varieties are grown as annuals).

Control: Mulch garden areas in spring to prevent pigweed or use a preemergence herbicide in spring. Pull weeds by hand or spray with a postemergence weed killer.

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Canada Thistle

Type: Broadleaf perennial

Size: To 6 feet tall and 3 feet wide

Where It Grows: Sunny lawn, landscape, or garden areas

Appearance: Canada thistle has spiny, gray-green leaves and purple flowers.

Control: Mulch your garden to prevent it in landscape areas. Use a postemergence herbicide in lawns in spring or fall, or dig the weed out by hand.

Test Garden Tip: Thistle has an extensive root system that can grow several feet out from the main plant.

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Knotweed

Type: Broadleaf annual

Size: To 8 inches tall and 2 feet wide

Where It Grows: Sunny or partly shaded lawn, landscape, or garden areas

Appearance: Knotweed is an invasive groundcover with blue-green leaves sparsely appearing on long stems.

Control: Prevent knotweed with a deep layer of mulch or apply a preemergence herbicide in spring. Once the plant grows, hand-pull or spot-treat it with a nonselective weed killer.

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Pokeweed

Type: Broadleaf perennial

Size: To 10 feet tall and 2 feet wide

Where It Grows: Sunny landscape or garden areas

Appearance: Identify this garden weed by its light green leaves, clusters of white flowers, and dark purple berries.

Control: Prevent pokeweed with a deep layer of mulch. Once the plant grows, hand-pull or spot-treat it with an herbicide.

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Poison Ivy

Type: Broadleaf perennial

Size: To 15 feet tall and wide

Where It Grows: Sunny or shady landscape or garden areas

Appearance: Poison ivy can be a vine, shrub, or groundcover. The weed has leaves divided into three leaflets and can sprout clusters of green berries.

Control: Prevent poison ivy with a deep layer of mulch. If the weed starts to grow in your yard, spot-treat it with an herbicide or wrap your hand in a plastic bag, pull the plant up, roots and all, and carefully invert the plastic bag around the plant, seal, and throw away.

Test Garden Tip: The plant contains oils that cause a severe allergic skin reaction in many people when touched. These oils are present even on dead leaves and can become airborne and inhaled if the plant is burned.

Identifying weeds with frilly or lacy leaves this spring

Like in prior springs, we often see a trend in the weed identification questions in certain parts of the state. This spring, a small mustard species with finely-divided (I like to say frilly or lacy) leaves is the most frequent plant requiring identification by our clients. There are several species we may run into in the spring with these lacy or finely-divided leaves. I’ve outlined the species in question, Descurainia species, and a few others that could look similar.

Tansy mustard and flixweed

Two very similar mustard species exist in the state of Iowa – tansy mustard (Descurainia pinnata) and flixweed (Descurainia sophia). From our perspective, identification to the species is not particularly important as they both usually act as winter annuals and management options would be similar for the two. Like other winter annuals, they flower and produce seed early in the spring, often allowing them to escape other management tactics and persist in disturbed areas. These are fairly common but mostly unimportant agronomic weeds in our current crop production system. We aren’t aware of these building up to economic levels in any crop fields.

Client-submitted image of a Descurainia species, probably tansy mustard.

Possible flixweed rosette in a field. Photo by Bob Hartzler.

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You’ll notice these weeds as rosettes (circular arrangement of leaves) that will bolt (produce a flowering stem) and grow to about 1-2.5 feet tall. Leaves are very finely-divided, and the entire plant is covered in fine hair. Both species have four-petaled yellow flowers and produce small, orange seed in seed pods called siliques. For those really interested in careful identification, the Illinois Wildflowers website reports that flixweed vegetation usually has a more blue appearance and produces seed pods that are thinner (~1 mm) and longer (1/2 inch in length) than tansy mustard.

Pineapple weed

Pineapple weed (Matricaria discoidea) is a very early annual species with ‘fern-like’ leaves that rarely shows up in crop fields but is common in residential landscapes and waste areas. The plants may be 3-12 inches tall and look like small bushes. The leaves and stems are hairless and may appear succulent. The plants produce small, inconspicuous, greenish-yellow flowers arranged in a dome shape. What this weed lacks in showy flowers, it makes up for in a smell that appropriately reflects its name – pineapple.

Pineapple weed growing in a landscaped area. Photo by Bob Hartzler.

A close-up of pineapple weed leaves shows the fern-like divisions and the start of an inconspicuous flower. Photo by Bob Hartzler.

Wild carrot (Queen Anne’s Lace)

Wild carrot (Daucus carota) is a biennial species that has a rosette shape similar to tansy mustard and flixweed, but matures to a larger, 2-5 foot tall plant with white flowers. It is common in pastures, hayfields, and non-crop perennial habitats. The rosette may look similar to tansy mustard or flixweed, with fine divisions in the leaves and a rosette up to 12 inches in diameter. Leaves and stems are usually covered in rough hair but may be glabrous or appear hairless as the plant ages. The white flowers are in an umbel (like an umbrella) shape with many short flower stalks originating from the same point, and the umbel is often flat across the top. Wild carrot is known for often having a single flower in the center of the umbel with purple petals. See more images of wild carrot here.

Wild carrot rosette in a crop field. Photo by Bob Hartzler.

Poison hemlock

Poison hemlock (Conium maculatum) is another biennial species that has finely-divided leaves, though this plant may already be bolting and is the largest of the species discussed here. Poison hemlock rosettes may be up to 2 feet in diameter and flowering plants are rarely less than 6 feet tall. Poison hemlock is usually a weed of perennial habitats like pastures, hayfields, or non-crop areas. Leaves of this species are much larger than the counterparts in this article; they usually have a wide base (more triangular-shape) and shiny appearance. The plant is hairless. As the plant matures, the leaf petioles and flowering stalk often have a waxy appearance with purple blotches. White flowers in a compound umbel shape are similar to wild carrot. See more images of poison hemlock here.

Poison hemlock leaf. Photo by Bob Hartzler.

Poison hemlock stems are hairless and often develop a waxy appearance with either purple spots or a purple overall color. Photo by Meaghan Anderson.

Common ragweed

The final frilly-leaved weed is common ragweed (Ambrosia artemisiifolia), a summer annual species that germinates early in crop fields and other disturbed areas. It grows to a mature height of about 3 feet tall and will often branch to look like a small, herbaceous bush. Common ragweed seedlings should be easily identified by the presence of round cotyledons at the base of the plant. Subsequent leaves are finely-divided and oppositely arranged during early growth. These plants do not produce a rosette like all other species noted in this article, but rather grow in an upright manner from emergence to maturity.

A common ragweed seedling has round cotyledons (first leaves) and lacy, oppositely-arranged subsequent leaves. Photo by Meaghan Anderson.

Have you seen either of the winter annual mustards with finely-divided leaves or their lacy look-a-likes out this spring? Check out the resources below for more information: