Field burweed

Soliva sessilis, the field burweed or lawn burweed, is a low-growing annual herb in the daisy family (Asteraceae), native to temperate South America (Argentina, Chile, Uruguay) and now widely naturalized as a weed in mild-winter regions of North America, southern Europe, Australia, and elsewhere. Plants form prostrate to ascending rosettes 5-20 cm across, with short stems that branch from the base. The leaves are alternate, soft, finely 2-3 pinnatisect with narrow linear segments giving a feathery appearance, 2-6 cm long, and sparsely hairy. The inflorescences are small, sessile, button-like discoid heads 4-8 mm across, nestled tightly in the leaf axils; they contain a few inconspicuous greenish florets surrounded by an involucre of leaf-like bracts. After flowering, each achene develops a sharp, persistent, hardened spine from the style base, producing the small painful "burs" that adhere to feet and footwear and disperse the seed. The species favours short turf, lawns, sandy paths, sports fields, and other disturbed open ground; it is regarded as a serious lawn pest in the southern United States.