Perennial weeds

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

Artichoke, Jerusalem

Helianthus tuberosus L.

Vegetative characteristics

• Cotyledons: Ovate to spatulate and rough.

• Leaves: Elliptic, hairy leaves with a prominent midvein and a short petiole becoming more lanceolate, large and rough as the plant matures. All leaves are toothed. Opposite leaf arrangement at the plant’s base, then becoming alternate above.

• Stem: White and hairy, becoming rough and hairy as the plant matures.

• Plant characteristics: Erect.

Flowering characteristics

• Flowers: Yellow flowers borne in heads, with a darker center.

Plant characteristics

• Growth habit: Erect and 6 feet or more in height.

• Roots: Roots bear fleshy tubers.

Bindweed, field

Convolvulus arvensis L.

Vegetative characteristics

• Cotyledons: Broadly heart-shaped with a shallow notch at the tip. Distinct venation and a long petiole

• Hypocotyl: Smooth, often purplish.

• Leaves: First leaves are heart-shaped with margins indented at the petiole. Later leaves are arrowhead-shaped, in an alternate leaf arrangement.

• Plant characteristics: Vine-like, twining or trailing.

Flowering characteristics

• Flowers: White to pinkish, funnel-shaped flowers that are about 1 inch in diameter. The flower stalk bears a pair of small green stipules below flowers.

• Seeds: Gray-brown and rough, with four seeds per capsule,.

Plant characteristics

• Growth habit: Vine-like and twining.

Bindweed, hedge

Calystegia sepium (L.) R.Br.

Vegetative characteristics

• Cotyledons: Broad with a deep notch at the tip.

• Leaves: Arrowhead-shaped with cut-away corners at the base, in an alternate leaf arrangement. Larger than field bindweed leaves.

Flowering characteristics

• Flowers and seeds: Large, funnel-shaped and white or pinkish flowers that are 2 inches in diameter.

• Seeds: Large, rough seeds, with two to four seeds per capsule.

Plant characteristics

• Growth habit: Vine-like and twining.

Nutsedge, yellow

Cyperus esculentus L.

Vegetative characteristics

• Leaves: Three-ranked, narrow, grass-like and mostly basal.

• Leaf sheath: Three-ranked with a triangular stem. Numerous fine veins visible.

• Ligule: None.

Flowering characteristics

• Inflorescence: Small, yellowish or yellowish-brown flowers in narrow spikelets on an umbrella-like inflorescence.

Plant characteristics

• Growth habit: Erect plant whose roots bear small, round vegetative tubers from which new plants can arise.

Quackgrass

Elymus repens (L.) Gould

Vegetative characteristics

• Leaf sheath: Open, round and pubescent.

• Leaf blade: May be smooth or pubescent.

• Ligule: Membranous and short.

• Auricles: Older leaves bear a pair of auricles (short, claw-like appendages attached to the leaf collar at the blade’s base).

Flowering characteristics

• Inflorescence: Spike with spikelets directly attached to the central axis (rachis). Several seeds are crowded into each spikelet.

Plant characteristics

• Growth habit: Extensive whitish rhizomes (underground stems) from which new plants can arise. Plants may also arise from seed.

Sowthistle, perennial

Sonchus arvensis L.

Vegetative characteristics

• Cotyledons: Oval and smooth with short stalks.

• Leaves: First leaves are ovate with slightly toothed or prickly margins. Later leaves are long and irregularly lobed, with prickles around leaf margins. Leaves clasp the stem at the base (no leaf petiole). Alternate leaf arrangement.

Flowering characteristics

• Flowers and seeds: Yellow flowers in heads that are 1 to 1.5 inches in diameter.

• Seeds: Reddish-brown, cylindrical and ribbed seeds are spread by the tuft of hairs at the tip.

Plant characteristics

• Growth habit: Erect, contains milky juice.

Thistle, Canada

Cirsium arvensis (L.) Scop.

Vegetative characteristics

• Cotyledons: Ovate to linear. Thick, fleshy and rough.

• Leaves: First leaves are ovate with sharp spines, while successive leaves are more wrinkled and spiny. Leaves on mature plants are very spiny and prickly with crinkled edges. Alternate leaf arrangement.

Flowering characteristics

• Flowers: Lavender flowers. Heads are about 3/4 inch in diameter.

• Seeds: Brown, cylindrical and smooth seeds are spread by a tuft of plume-like hairs.

Plant characteristics

• Growth habit: Erect with an extensive lateral root system from which plants spread in colonies.