Weeds with yellow flowers in lawns, beds and roadsides

Look-alike tests, pair by pair

Dandelion or cat's ear. Pick a stalk. NC State describes dandelion stalks as hollow, leafless and unbranched with milky sap, and leaves deeply toothed with teeth pointing backward. Cat's ear has densely hairy leaves up to 6 inches in a rosette about a foot across, and wiry stalks that often branch. Hairy leaf plus branched stalk means cat's ear.

Sow thistle or dandelion. Spiny sow thistle grows a leafy, upright stem with clusters of 1 to 5 flower heads, and its glossy leaves have soft spiny teeth and rounded lobes that wrap around the stem. A dandelion never has leaves on its flower stalk.

Creeping or meadow buttercup. Both have glossy five-petaled flowers. The RHS describes creeping buttercup leaves divided into three deeply lobed leaflets with serrated edges, often pale-marked, covered in small pale hairs, on a plant that sends out rooting runners and reaches about 50 cm. NC State describes meadow buttercup as an upright plant whose leaves are cut into narrow, pointed lobes.

Wood sorrel, black medic or hop clover. All three carry three leaflets. NC State gives yellow wood sorrel heart-shaped leaflets and single bright yellow flowers. Black medic's middle leaflet sits on a short stalk, and its flowers sit in tiny ball-shaped heads of 15 to 50. Small hop clover carries 3 to 15 flowers per head from May to October, and the heads turn yellowish-brown with age.

Indian mock strawberry. Indian mock strawberry has three toothed leaflets and a single five-petaled yellow flower on each stalk, with green three-toothed bracts spreading beneath it, and later a red fruit that looks like a small strawberry.

Ragwort, groundsel and tansy. All three are in the daisy family and carry flat-topped yellow clusters. The RHS ragwort guide gives stems up to 1.5 m, branched in the upper half, with large flat-topped clusters of yellow daisy-like flowers from July to October. Common groundsel is a small bed weed with petal-less heads and hollow purple stems. Tansy has button heads without petals and fern-like leaves that smell of camphor when crushed.

Wild parsnip and other yellow umbels. Wild parsnip is the yellow umbel to know. The Government of Ontario describes yellowish-green flower clusters on a tall stalk in the plant's second year, after a low rosette in the first, along roadsides, meadows, open fields and railway embankments. NC State adds a hollow, grooved, hairless stem and compound leaves of about 9 leaflets. Any yellow umbel on a roadside deserves a look-but-don't-touch rule until it is named; our wild parsnip page has the full look-alike list.

Yellow weeds that harm skin, pets or livestock

These listings come from the sources named; a weed missing here has not been shown to be harmless.

• Wild parsnip. The Government of Ontario says its sap contains chemicals that make skin react to sunlight, causing intense burns, rashes or blisters. NC State rates it medium severity and advises protective equipment when handling it.
• St. John's wort. NC State says skin contact with the sap, or eating the plant, can cause photosensitivity in some people, and lists it as a problem for cats, dogs and horses.
• Common tansy. Rated high severity by NC State, which also notes it can cause contact dermatitis.
• Ragwort and groundsel. The RHS says ragwort is poisonous to horses and livestock, that eating it green or dried can cause serious liver damage and can be fatal, and that all parts stay toxic when wilted or dried. NC State rates common groundsel medium severity and lists it as a problem for cats, dogs and horses.
• Buttercups, wood sorrel and lesser celandine. NC State lists meadow buttercup as medium severity, and yellow wood sorrel and lesser celandine as low severity and a problem for cats, dogs and horses. The ASPCA lists the shamrock plant (Oxalis species) as toxic to dogs, cats and horses.
• Dandelion. NC State notes its sap can irritate skin.

Wear gloves and long sleeves when you pull any of these, and wash skin that touches wild parsnip sap straight away, out of the sun. If a pet has eaten one, call your vet or the ASPCA Animal Poison Control Center at (888) 426-4435. For a person, call Poison Control at 1-800-222-1222 in the US, or NHS 111 in the UK. This site gives no edibility advice for any weed on this page.

Removing yellow weeds without guessing

Identification comes first because the method depends on the plant. Dandelion and cat's ear come back from a deep root, so they need the whole root lifted, ideally after rain. Creeping buttercup spreads by rooting runners and dense clumps of roots (RHS), so lift the runners with the parent plant. Ragwort can regrow from root fragments, and the RHS advises removing mature plants before they set seed and not putting the flowers or seedheads in a home compost bin, since cut flowering plants can still set seed. Purslane and groundsel are annuals that set seed fast; pull them before they flower.

If you decide to use a herbicide, follow the label and local rules, and check that the label names the weed you have identified. For grazing land, check local guidance on ragwort control.

How a photo settles it

Yellow daisy-like weeds are where a photo needs help, because the flowers look alike and the deciding traits sit lower down. Take one photo of the open flower and a second of the whole plant with its leaves and stem, so the hairs, the branching and the leaf shape show.

Plant Identifier names the plant from one photo and gives the common and scientific names, which you can check against the field mark in the table. The app shows one answer with no confidence score and no list of alternatives, so run the matching test yourself: hollow stalk, hairy leaf, leaflet tip. If it names wild parsnip, treat that as a reason to keep your hands off. For a dog that grazes the lawn, Plant Identifier's Toxicology tool writes notes for people, dogs and cats; read them alongside the ASPCA entry rather than instead of it.