The Ultimate Guide to Identifying Common Lawn Weeds

Barnyard Grass – Echinochloa crusgalli 

 

This is a warm-season grass and belongs to the annual category. It has a flattened stem near the base. The lower portion of the plant is reddish purple. The seed head is branched into 6 or 8 segments.

 

Photo by Steve Dewey, Utah

Bedstraw – Galium app.

 

This is an annual cool-season weed with weak and squarish stems. It has tiny saw-tooth appendages. The leaves and stipules form “Whorls”.

 

Black Medic – Medicago lupulina

 

This is an annual short-lived perennial weed with trailing stems. It has 3 leaflet leaves with prominent veins. It has small yellow flower clusters. It normally pods at maturity.

 

Bromegrass – Bromus inermis

 

This is a cool-season perennial weed with prominent veins. It is a livestock forage. The lower stem is almost white. The leaves are  ⅜ to ½  wide with M or W across the leaf blade. 

Photo by Donald Cameron

Chickweed – Stellaria media

 

This is an annual weed with small, opposite, smooth, and oval leaves. It has weak vining stems. The flowers are small white star-like in appearance.

 

Crabgrass – Digitaria spp.

 

This is an annual warm-season grass with prostrate stems. It’s rooted down where each joint contacts ground or wet grass. The seed head is divided into fingerlike segments. Leaves are hairy, short, and broad with crinkled margins. The stems usually grow amongst lawn species and are difficult to effectively combat with a mower.

 

Creeping Bellflower – Campanula rapunculoides

 

This is a perennial cool-season weed. The flowers are showy, deep blue to purple. It has vigorous underground root systems and escaped ornamentals. 

 

Dandelion – Taraxacum spp.

 

This is a perennial cool-season weed that blooms from March to late December. It’s common in Utah. It is one of the showiest lawn weeds.

 

Field Bindweed – Convolvulus arvensis

 

This is a perennial cool season weed that is extremely very difficult to control. The leaf tips and basal lobes are rounded in shape. The flowers are white to light pink. The vines are readily spread by seeds and underground roots. 

Fox tail – Setaria spp.

 

This is an annual warm-season weed that shares the same growth conditions as Crabgrass. There are 3 types which are yellow, red, and green foxtail.

Goose grass – Eleusine indica

 

This is an annual warm-season grass. The stem is flattened and whitish near the base. The flowers are more thicker and robust than the Crabgrass. It has extensive fibrous root systems. It grows where bluegrass is thin.

Ground ivy – Glechoma hederacea

 

This is a perennial cool-season weed. It thrives in shade with lavender to blue funnel form flowers. It has a square root system that root wherever the joint touches the ground. 

Henbit – Lamium amplexicaule

 

This is a winter annual weed with squarish stems. It has lavender to blue flowers and the leaves are opposite. It blooms from late March to April. The plant is upright in appearance. 

Kochia – Kochia scoparia

 

This is an annual weed. The first leaves have a silvery pubescence. The leave and stem colors vary from greenish-yellow to greenish-red. It’s a very adaptable weed. The germination starts in late March and continues throughout the summer. 

 

Musk thistle – Carduus nutans

 

This is a biennial weed. The leaves are free of hair and have light-colored midrib and leaf lobes are edged in the grey-green spiney. It has large ornate purple flowers.

 

Nimblewill – Muhlenbergia schreberi

 

This is a perennial warm season weed with wiry fine stems root at nodes. It has a shallow fibrous root system. Its growth is delayed in spring and early fall dormancy.

 

Plantain – Plantago spp.

 

This is a cool season perennial weed that has rosette with prominently veined leaves. Leaves are oval-shaped and 2 to 3 inches across. Its stems are reddish or purple and also have a tail-like like seed heads. 

 

 

Prostrate knotweed – Polygonum aviculare

 

This is an annual weed with a long white tap root. It has a wiry stem, very leafy, with a papery sheath at each joint. The leaves have a bluish cast and three-cornered, light brown seeds that are shiny black at maturity.

Prostrate Pigweed – Amaranthus Blitoides

 

This is a warm-season annual weed. The prostrate grows from a taproot. It has smooth stems and a or that ranges from light to reddish green. It usually spreads between 1½ – 2 feet. The seeds are less-shaped, usually small and shiny black.

 

Prostrate Vervain – Verbena bracteata

 

This is a warm-season annual weed. Low-growing, hairy in the description. The stems branch freely forming circular patterns of growth. The leaves are wedge-shaped and toothed. It has a taproot.

 

PunctureVine – Tribulus Terrestris

 

This is a warm-season annual weed. It’s prostrate and freely branching. The leaflets are bright green and slightly hairy. The flowers are yellow. The seeds angled with two stout spines. It has a taproot.

 

 Photo by Richard Old

Purslane – Portulaca oleracea

 

This is a warm-season annual weed. The leaves and stems are fleshy or succulent, and reddish. The stems root when they touch the ground. The flowers are small and yellow. The seeds are very small and black.

 

 

Quackgrass – Agropyron repens

 

This is a cool season of perennial wheatgrass. It spreads by underground stems and roots •It has a ring of root hairs every inch along white underground stems. The lower leaf sheath is hairy. The leaf blades are twice the width of bluegrass.

 

 

Red sorrel – Rumex acetosella

 

This is a cool season perennial weed. It has creeping roots and seeds. The leaves are spear-shaped. It has lacy reddish flowering stalks. The seeds are small, three-sided, and reddish brown.

 

 

Sandbur – Cenchrus pauciflorus

 

This is a warm season of annual weed. The stems are flattened and branched. It’s found in poorly maintained turf. It is often confused with yellow foxtail before the formation of spiny burrs.

 

 

Shepherd’s Purse – Capsella bursa-pastoris

 

This is winter annual weed. Its deeply lobed leaves form rosettes. It has triangular seed pods filled with tiny brownish seeds resembling purses once carried by shepherds. 

 

 

Speedwell – Veronica spp.

 

This is a winter or early spring annual weed. The leaves are small with scalloped edges. The flowers have a color of light blue with a white throat. It’s divided seed pods are almost heart-shaped it’s a low-growing weed.

 

 

Spurge – Euphorbia maculata

 

This is a warm-season annual weed. it has milky sap with leaves with or without reddish brown spots. The seeds are born in three’s capsules. It is prominent in July, August, and September.

 

Tall Fescue – Festuca arundinacea

 

This is a cool-season perennial weed The leaf veins are strongly fibrous and when mowed fibers show on the edges. The mature leaf blades may be one-half an inch wide, ribbed above and shiny below. The lower portions are reddish to purple.

 

Violet – Viola spp.

 

This is a cool season perennial weed. The flower color varies from very light blue to deep purple. It prefers light shade. It blooms in spring.

 

Aunt Lucy – Ellisia nyctelea

 

This is a cool season annual weed. It grows in shade. It has small white flowers and grey-green leaves.

 

Photo by Smith,R.W.

 

White Clover – Trifolium repens

 

This is a cool season perennial weed. It spreads by below and above-ground stems. The flowers are white, sometimes tinged pink. The seeds live for 20 years or more in soil.

 

 

Yellow nutsedge – Cyperus esculentus

 

This is a warm season of perennial weeds. The lower portion of the plant is fibrous and brown. The roots often terminate with small nutlets. The seed heads appear bur-like. It has triangular stems of sedges that produce 3-ranked leaves near the ground.

 

 

Yellow wood sorrel – Oxalis stricta

 

This is an award-season perennial weed. The leaves are palmately divided into three leaflets. It has funnel-form yellow flowers. The seed head has a long beak and a sour taste from calcium oxalate.