Common "Obnoxious" Weeds

This is a list of common weeds that are not on our noxious weed list, but are "obnoxious" weeds. They may look similar to some noxious weeds on our list, but are different.

Prostrate Spurge

Euphorbia maculata

• Forms a mat, growing close to the ground and spreading out
• In the Spurge Family, so contains that milky latex sap that is toxic and a skin irritant
• Annual plant, forms lots of seeds
• Grows in cracks, disturbed soil, and many other areas

Bur Buttercup

Ranunculus testiculatus

• Often confused with Puncturevine
• It is one of the first plants that flowers after snowmelt, (many months before puncturevine)
• Grows clustered together into what looks like a mat
• develops sharp spiny fruit on top of stem (which is how it is confused with puncturevine)
• Small, yellow flowers
• Annual weed, native of southeastern Europe 
• Commonly seen in gardens, pastures, wastes areas, and along roadsides
• Winter annual that emerges, flowers, and sets fruits in the spring, when temperatures climb into the 45 to 50-degree range 
• Toxic species because it contains ranunculin, a chemical that changes into to protoanemonin, a highly toxic compound. The transformation of ranunculin into protoanemonin occurs when the plant is crushed. 
• There are reports of sheep poisonings after ingesting bur buttercup.
• It is important to control bur buttercup before they produce flowers and seeds
• Hoeing, pulling and digging can control bur buttercup, as well as certain herbicides 

Common Mallow

Malva neglecta

• Spreading annual, rarely a biennial
• Flowers are pink to white in color
• Commonly found in lawn and turf areas

Common Mullein

Verbascum thapsus

• Biennial plant
• Grows tall, up to 6 feet or more
• grows in a wide variety of habitats
• needs open ground to germinate and grow
• reproduces by seed
• Can be a host for many insects that can damage other plants
• Produces a large, fuzzy rosette the first year
• Makes a shallow taproot

Prickly Lettuce

Lactuca serriola

• Annual or biennial
• Has spines on stems and leaves
• Produces a milky sap when cut
• Commonly seen on roadsides and other disturbed areas

Purple Mustard

Chorispora tenella

• Annual plant, reproduces by seed
• Has a strong, unpleasant odor
• Can reduce yield in grain fields
• Can taint milk if grazed on by dairy cattle

Redroot Pigweed

Amaranthus retroflexus

• Annual plant
• Can reach heights of up to about 9 ft.
• Forms a tumbleweed
• Inflorescence is a dense cluster at the top of the stem
• Eaten as a vegetable in different parts of the world

Redstem filaree

Erodium cicutarium

• Annual, sometimes biennial
• Flowers are bright pink, 5 petaled
• Seed pods are pointy like a storks bill
• Leaves are feathery looking

Russian Thistle

Salsola kali

• Commonly seen tumbleweed
• Breaks off and spreads seed as it tumbles
• Annual plant, tends to grown in salty, sandy soils
• Develops sharp spines once mature

Spotted Spurge

Chamaesyce maculata

• ‍Prostrate annual spurge
• Red or pink flowers
• Leaves have central spot of dark purple

Spring Draba

Draba verna

• Annual plant
• Small white flowers with four deeply lobed petals
• Member of the Mustard family (Brassicaceae)
• Grows in meadow areas and disturbed areas