Beaked-sandbur

Solanum rostratum, the buffalo-bur or beaked-sandbur nightshade, is an aggressive, taprooted annual herb of the Solanaceae native to the central plains of North America and now widely naturalised across temperate regions worldwide. It grows 30-80 cm tall with stout, much-branched, conspicuously prickly stems, the prickles straight, yellowish, and up to 1 cm long. The alternate leaves are 5-15 cm long and deeply pinnately lobed in a manner suggesting a coarse oak leaf, the surfaces studded with stellate hairs and stout prickles along the midrib and veins. Bright yellow, somewhat zygomorphic, 5-lobed corollas 2-3 cm across are produced in few-flowered racemes through summer; the calyx is densely prickly and enlarges in fruit, eventually enclosing a globose berry. The fruits are completely sheathed in a spiny, beaked, bur-like calyx that breaks off and disperses by clinging to animal fur and clothing.