Soliva sessilis aka Lawn Burrweed

Soliva sessilis is a small annual in the daisy family, Asteraceae. Common names include lawn burweed, bindi weed, and spurweed. Its native range stretches from Peru to Brazil and southern South America. Kew places it in the subtropical biome. It grows fast and often appears in lawns during winter. In the United States, it has become a troublesome lawn weed.

Plants reach about 0.17 feet [0.05 metres] tall. Their spread reaches about 0.5 feet [0.15 metres]. Creeping stems send out shoots that form low patches. Each plant has one to ten green stems with purple spots. Stem hairs range from sparse to dense. The small green leaves have deep divisions and a parsley-like look. Soft hairs cover the blades, which grow on short stalks. The first leaves form a rosette close to the ground. Later leaves also grow along the stems.

Small yellow-green flower heads sit where leaves meet the stems. They contain disk flowers but lack ray flowers. Flowering runs from February to July in the NC State account. Each head becomes roughly half-round as its fruits mature. The fruit is an achene, though gardeners may call it a seed. It is flat, with lobed wings along both sides. Two spines project from one end; one has a sharp point. Fruits ripen during spring and summer. They catch on shoes, clothes, and equipment, helping the plant spread.

Lawn burweed grows in full sun or partial shade. NC State lists sandy soil and sites that become wet at times. It thrives in worn, stressed, or bare parts of lawns. Healthy turf competes with it and can limit its spread. Its low growth keeps it below the reach of mowing. Pulling plants with their roots before seed forms helps control them. Soil aeration can also reduce its presence. NC State also lists broadleaf herbicides as a control option.

Its sharp fruits make infested lawns painful to cross barefoot. Dogs and cats may avoid these patches too. This is a physical hazard, not evidence of poisoning. The supplied sources give no food use or toxicity assessment. NC State reports no major insect or disease problems. It also records invasive status with the North Carolina Invasive Plant Council. Its main landscape role in these sources is as an unwanted lawn weed.