Madagascar ragwort

Senecio madagascariensis, Madagascar ragwort or fireweed, is an erect, largely glabrous herb of the daisy family (Asteraceae) growing 20–60 cm tall, occasionally becoming somewhat woody at the base. The alternate leaves are bright green, narrow to elliptic, 2–7 cm long, with lobed or serrate margins. Small bright yellow daisy-like flowerheads about 1–2 cm across are produced on slender stalks and contain both ray and disc florets. Fruits are brown achenes 1.5–2.5 mm long crowned with a pappus of fine hairs. The species is native to southern Africa, Madagascar and surrounding regions and has become a serious invasive weed of pastures and disturbed ground in Australia, New Zealand, Hawai‘i, Argentina, Japan, Mexico, Kenya and elsewhere. All parts contain pyrrolizidine alkaloids that are hepatotoxic to livestock.