Tropical burnweed

Erechtites valerianifolius, the tropical burnweed or Brazilian fireweed, is an erect, soft-stemmed annual herb in the Asteraceae growing 30–100 cm tall, with hollow, ridged, sparsely pubescent stems that branch in the upper half. Leaves are alternate, sessile and somewhat clasping, 6–15 cm long, deeply pinnately lobed into 5–9 pairs of narrow, irregularly toothed lobes, the terminal lobe larger and lanceolate; the foliage is bright green, thin in texture, and faintly aromatic when crushed. The inflorescence is a loose, terminal corymb of slender, cylindrical flower heads each 8–15 mm long; phyllaries are in a single neat row of linear-lanceolate green bracts, sometimes purple-tipped, with a few small calyculate bracts at the base. The heads contain only inconspicuous tubular florets, the outer female and the inner perfect, all whitish to pale yellow or pinkish and barely exceeding the involucre. Fruits are slender, ribbed achenes 2–3 mm long crowned with a long, soft, silky white pappus. It is native to tropical America and naturalized as a weed of disturbed open ground across the Old World tropics.