Annual broadleaf weeds

In this guide, you’ll find photos and identifying characteristics of the annual broadleaf weeds common to Minnesota.

Broadleaf weed characteristics

Use these characteristics to help identify broadleaf weed seedlings.

Leaves

Broadleaf weed seedlings, in contrast to the grasses, usually have wider leaves with net-like venation.
Broadleaves are dicots and have two cotyledons or seed-leaves. These usually emerge above the soil and expand to become the first visible “leaves.” The true leaves then develop above the cotyledons (Figure 1). However, in some broadleaf species, the cotyledon (seed) remains in the soil and the plumule (growing point and cluster of undeveloped true leaves) emerges above the soil line.
The shape and size of the cotyledons and first true leaves vary considerably among species (Figure 2).
Leaves may be alternate or opposite in arrangement on the stem. In some cases, the second leaf may appear so closely behind the first leaf that they appear to be opposite but later prove to be alternate.
The true leaves of broadleaf weeds usually have a petiole (leaf stalk). However, in some species, the true leaves may be sessile (without a leaf petiole).
Leaf petioles in the Buckwheat (Polygonaceae) plant family are encircled by a membranous sheath, called an ochrea.

Other plant characteristics

The stem below the cotyledons is called the hypocotyl. The stem above the cotyledon is the epicotyl.
Cotyledons are usually hairless but may be rough, while true leaves and plant stems may be hairy or smooth.
Seedlings may have an erect stem, be viny or twining in growth habit or be prostrate (growing flat on the ground).

Figure 1: Vegetative broadleaf plant parts. Illustration updated by Lauren Cooper.

Amaranth family ID Waterhemp Palmer amaranth and redroot pigweed

Waterhemp

Vegetative characteristics

Cotyledons: Often more egg-shaped than other pigweed species.
Leaves: Long, narrow leaves. Smooth stems and leaves, unlike redroot pigweed.
Plant characteristics: Erect.

Flowering characteristics

Leaves: Usually long and narrow. Smooth stems and leaves.
Flowers and seeds: Flowering structure near the top of the plant and at the tips of the branches. Either male or female.
Plant characteristics: Erect.

Waterhemp seedling. Source: Bruce Ackley, The Ohio State University, Bugwood.org.

Waterhemp in a Minnesota soybean field. Photo: Fritz Breitenbach.

Waterhemp’s flowering structure near the top of the plant and at the tips of branches. Source: Bruce Ackley, The Ohio State University, Bugwood.org.

Palmer amaranth

Amaranthus palmeri

Vegetative characteristics

Cotyledons: Oval.
Leaves: Ovate- to diamond-shaped, giving it a poinsettia-like appearance. Smooth. May have a leaf tip hair. May also have a v-shaped watermark.
Petiole: As long or longer than the leaf.
Stem: Smooth, unlike redroot pigweed, which is hairy.

Flowering characteristics

Reproduction: Plant is dioecious (male and female plants). Female inflorescences have sharp, spiny bracts. Male flowering structure is soft and sheds pollen.
Inflorescence: Main terminal seed head (inflorescence) is up to 3 feet long.
Seed production: Prolific seed producer. A single female plant can produce 100,000 to 500,000 seeds.

Plant characteristics

Height: Can reach 6 to 7 feet in unmown areas.
Overall: Plant is smooth with no hairs on stems and leaves, unlike redroot pigweed.

Additional guidance

Preventing Palmer amaranth in Minnesota
Palmer amaranth in Minnesota: information from the Minnesota Department of Agriculture
Amaranth identification and biotypes
Comparing Palmer amaranth and tall waterhemp

Palmer amaranth seedlings. Photo taken 11 days after emergence.

Photo of hand holding a weed, taken from above. Shows a poinsettia-like appearance of Palmer amaranth. — Poinsettia-like appearance of Palmer amaranth. Photo: Rebekah D. Wallace, University of Georgia, Bugwood.org.

Palmer amaranth plant from Yellow Medicine County

Close-up of female Palmer amaranth plant found in Yellow Medicine County. Note the spiny bracts. Photo: Bruce Potter.

Hand holding a leaf, which shows the long petiole of Palmer amaranth. — Long petiole of Palmer amaranth. Photo: Ross Recker, University of Wisconsin-Madison, Bugwood.org.

Redroot pigweed

Amaranthus retroflexis

Vegetative characteristics

Cotyledons: Linear with short petioles. Lower surface and midvein on upper surface are reddish.
Hypocotyl: Light red.
Leaves of seedling: Ovate and indented at the tip with a prominent midvein. Alternate leaf arrangement with purplish petioles.
Leaves of mature plant: Slightly toothed. Alternate leaf arrangement with a long petiole.

Flowering characteristics

Flowers: Small greenish flowers, subtended by bristles.
Seeds: Black and shiny.

Plant characteristics

Growth habit: Erect.
Pubescence: Very fine hairs throughout the plant, unlike tall waterhemp and Palmer amaranth.
Roots: Tap root is often reddish.

Redroot pigweed seedling. Photo: Phil Westra, Colorado State University, Bugwood.org.

Redroot pigweed. Source: Robert Videki, Doronicum Kft., Bugwood.org.

Redroot pigweed’s small, greenish flowers.

Buckwheat, wild

Vegetative characteristics

Cotyledons: Linear.
Hypocotyl: Short, reddish and often covered with short, bristle-like projections.
Leaves: Heart-shaped with entire (smooth) margins. Alternate leaf arrangement.
Petiole: Ochrea (sheath) present at the base of a long petiole.

Flowering characteristics

Flowers: Small and greenish.
Seeds: Triangular seeds.

Plant characteristics

Growth habit: Viny and twining.

Wild buckwheat seedling. Photo: Strand Memorial Herbarium.

Wild buckwheat. Photo: Strand Memorial Herbarium.

Wild buckwheat’s triangular seeds: Shows eight seeds of slightly different sizes and colors. — Wild buckwheat’s triangular seeds. Photo: Strand Memorial Herbarium.

Buffalobur

Vegetative characteristics

Cotyledons: Linear.
Leaves: Deeply lobed and alternate. Yellow spines develop on midrib and veins.
Petioles and stem: Prickly with yellow spines.

Flowering characteristics

Flowers: Yellow.
Seeds: Fruit a berry-like capsule with long, yellow spines.

Plant characteristics

Growth habit: Erect or trailing.

Buffalobur seedling. Photo: Strand Memorial Herbarium.

Buffalobur. Photo: Strand Memorial Herbarium.

Buffalobur seed capsules. Photo: Strand Memorial Herbarium.

Cocklebur, common

Vegetative characteristics

Cotyledons: Long and linear, spread up to 80 millimeters. Tend to be triple-veined at the base with no petiole.
Hypocotyl: Rough and purplish.
Leaves: Ovate and coarsely toothed or lobed with three prominent veins and a rough surface. Opposite leaf arrangement, then becoming alternate.

Flowering characteristics

Flowers and seeds: Greenish flowers.
Seeds: Fruit is a spiny bur containing two seeds.

Plant characteristics

Growth habit: Erect.

Common cocklebur seedling. Photo: Strand Memorial Herbarium.

Common cocklebur. Photo: Strand Memorial Herbarium.

Common cocklebur’s spiny bur. Photo: Strand Memorial Herbarium.

Kochia

Vegetative characteristics

Cotyledons: Oval and very small, spreading about 11 millimeters. Gray or frosty-green on the upper surface, and red on the lower surface.
Hypocotyl: Reddish to purplish.
Leaves: Small, linear and densely hairy. First leaves are opposite, later alternate.
Stems: Often turn reddish in the fall.

Flowering characteristics

Flowers: Small and greenish.
Seeds: Small, one-seeded fruit.

Plant characteristics

Growth habit: Erect and bushy.

Kochia seedling. Source: Phil Westra, Colorado State University, Bugwood.org.

Kochia. Source: Steve Dewey, Utah State University, Bugwood.org.

Lambsquarters, common

Vegetative characteristics

Cotyledons: Ovate with red on lower surface and light green on upper with a white, mealy appearance.
Hypocotyl: Light red.
Leaves: Slightly toothed with a white, mealy surface. Opposite leaf arrangement, then becoming alternate.

Flowering characteristics

Flowers and seeds: Gray-green flowers in small, round clusters.
Seeds: One-seeded fruit in a star-shaped hull. Hulled seed is small, black and round.

Plant characteristics

Growth habit: Erect with many branches.

Common lambsquarters seedling. Photo: Strand Memorial Herbarium.

Common lambsquarters weeds in a field — Common lambsquarters. Source: Robert Videki, Doronicum Kft., Bugwood.org.

Common lambsquarters’ gray-green flowers in small, round clusters. Photo: Strand Memorial Herbarium.

Common lambsquarters seeds. Photo: Strand Memorial Herbarium.

Marshelder

Vegetative characteristics

Cotyledons: Short and oval, with broad petioles and blunt tips.
Hypocotyl: Often turns reddish.
Leaves: Ovate, toothed leaves with a long petiole. Opposite leaf arrangement with bristly, hairy petioles and stems. Seedling leaves are also hairy.

Flowering characteristics

Flowers and seeds: Small, greenish-yellow flowers in clusters.
Seeds: One-seeded fruit.

Plant characteristics

Growth habit: Erect.

Marshelder seedling. Photo: Strand Memorial Herbarium.

Marshelder. Photo: Strand Memorial Herbarium.

Mustard, wild

Vegetative characteristics

Cotyledons: Wider than long with a shallow, oval notch or indentation at the tip.
Hypocotyl: Usually reddish.
Leaves: Toothed or lobed, rough and hairy. Alternate leaf arrangement.

Flowering characteristics

Flowers: Yellow flowers with four petals.
Seeds: Fruit is a many-seeded cylindrical capsule with round seeds.

Plant characteristics

Growth habit: Erect or trailing.

Wild mustard seedling. Photo: Strand Memorial Herbarium.

Wild mustard’s yellow flowers. Photo: Strand Memorial Herbarium.

Wild mustard’s cylindrical capsule. Photo: Strand Memorial Herbarium.

Wild mustard’s round seeds. Photo: Strand Memorial Herbarium.

Nightshade, black

Vegetative characteristics

Cotyledons: Ovate.
Leaves of seedling: Ovate and dark green with prominent veins. Alternate leaf arrangement with purplish petioles.
Leaves of mature plant: Coarsely toothed, in an alternate leaf arrangement.

Flowering characteristics

Flowers and seeds: White to lavender flowers with yellow centers.
Seeds: Greenish berry fruit that turns black at maturity.

Plant characteristics

Growth habit: Erect or trailing.

Black nightshade seedling. Photo: Strand Memorial Herbarium.

Black nightshade. Photo: Strand Memorial Herbarium.

Black nightshade flowers. Photo: Strand Memorial Herbarium.

Ragweed, common

Vegetative characteristics

Cotyledons: Linear to somewhat oval and thick. Veined at the base on lower surface. Thick and waxy.
Hypocotyl: Purple to dark green.
Leaves: Deeply lobed, becoming fern-like with dense, white hairs. Opposite leaf arrangement at the base of the plant, and an alternate arrangement above.
Stems: Densely hairy.

Flowering characteristics

Flowers and seeds: Small, yellowish-green flowers. Separate male and female flowers on the same plant.
Seeds: Small, crown-shaped seeds.

Plant characteristics

Growth habit: Erect.

Common ragweed seedling. Photo: Strand Memorial Herbarium.

Common ragweed. Photo: Strand Memorial Herbarium.

Common ragweed’s small, crown-shaped seed. Photo: Strand Memorial Herbarium.

Ragweed, giant

Vegetative characteristics

Cotyledons: Large and broadly ovate. Thick and waxy.
Hypocotyl: Purple.
Leaves: Deeply three- to five-lobed and rough-surfaced. Opposite leaf arrangement, except at the top of the plant.

Flowering characteristics

Flowers: Small, greenish-yellow flowers. Separate male and female flowers on the same plant.
Seeds: Crown-shaped seeds that are 1/4 inch or more across.

Plant characteristics

Growth habit: Erect.

Giant ragweed seedling. Photo: Strand Memorial Herbarium.

Giant ragweed in a field — Giant ragweed. Photo: Strand Memorial Herbarium.

Giant ragweed’s crown-shaped seeds. Photo: Strand Memorial Herbarium.

Smartweed, Pennsylvania

Vegetative characteristics

Cotyledons: Linear on one edge, curved on the other. Reddish blotch on the lower surface.
Hypocotyl: Reddish and smooth.
Leaves: Long, lanceolate shape with entire (smooth) leaf margins in an alternate leaf arrangement.
Petiole: Ochrea at the base of the short petiole. Ochrea lacks a fringe of hairs at the top, which helps distinguish it from other similar weeds.
Stems: Swollen stem nodes.

Flowering characteristics

Flowers and seeds: Flowers in pink, raceme-like clusters.
Seeds: Shiny, lens-shaped seeds.

Plant characteristics

Growth habit: Erect or trailing.

Pennsylvania smartweed seedling. Photo: Strand Memorial Herbarium.

Pennsylvania smartweed. Photo: Strand Memorial Herbarium.

Pennsylvania smartweed ochrea. Photo: Strand Memorial Herbarium.

Pennsylvania smartweed’s flower. Photo: Strand Memorial Herbarium.

Pennsylvania smartweed’s shiny, lens-shaped seeds. Photo: Strand Memorial Herbarium.

Sunflower, wild

Vegetative characteristics

Cotyledons: Oval and rough.
Leaves: Coarsely toothed, rough and hairy. Opposite leaf arrangement at the base of the plant, and an alternate arrangement above.
Petiole: Long.

Flowering characteristics

Flowers and seeds: Yellow flowers in large heads with a dark center.
Seeds: Large, oblong seeds with many per head.

Plant characteristics

Growth habit: Erect and tall.

Wild sunflower seedling. Photo: Strand Memorial Herbarium.

Wild sunflower. Photo: Strand Memorial Herbarium.

Large, oblong wild sunflower seeds. Photo: Strand Memorial Herbarium.

Thistle, Russian

Vegetative characteristics

Cotyledons: Linear and thread-like with no petioles.
Hypocotyl: Reddish.
Leaves: Very narrow, thread-like and cylindrical. First leaves appear in an opposite arrangement, and later become alternate and spine-tipped.
Stems: Often streaked with red.

Flowering characteristics

Flowers and seeds: Small, grayish-green flowers.
Seeds: Coiled.

Plant characteristics

Growth habit: Erect.

Russian thistle seedling. Photo: Strand Memorial Herbarium.

Russian thistle. Photo: Strand Memorial Herbarium.

Russian thistle’s coiled seeds. Photo: Strand Memorial Herbarium.

Velvetleaf

Vegetative characteristics

Cotyledons: Heart-shaped with blunt tips.
Leaves: Large, heart-shaped, velvety, soft and hairy. Alternate leaf arrangement.
Stems: Pubescent.

Flowering characteristics

Flowers: Large and yellow.
Seeds: Fruit is a button-like capsule with numerous heart-shaped seeds.

Plant characteristics

Growth habit: Erect with many branches and a strong odor.

Velvetleaf seedling next to a ruler, showing it's about 1.25 inches wide — Velvetleaf seedling. Photo: Strand Memorial Herbarium.

Velvetleaf in a field — Velvetleaf. Source: Jan Samancek, State Phytosanitary Administration, Bugwood.org.

Velvetleaf’s yellow flowers. Photo: Strand Memorial Herbarium.

Four of velvetleaf’s heart-shaped seeds. — Velvetleaf’s heart-shaped seeds. Photo: Strand Memorial Herbarium.

Gerald R. Miller, former Extension agronomist and Oliver E. Strand, former Extension agronomist

Acknowledgements

In cooperation with NCR Educational Materials Project.

Issued to further Cooperative Extension work, Acts of Congress of May 8 and June 30, 1914, in cooperation with the U.S. Department of Agriculture and Cooperative Extension Services of Illinois, Indiana, Iowa, Kansas, Michigan, Minnesota, Missouri, Nebraska, North Dakota, Ohio, South Dakota and Wisconsin and Charles H. Casey, former interim dean and director, University of Minnesota Extension.

Sponsored by the Extension services of Illinois, Iowa, Kansas, Michigan, Minnesota, Nebraska, North Dakota and Ohio, in cooperation with SEA-Extension, U.S. Department of Agriculture.

Reviewed in 2022