coastal plain yellowtops

Coastal plain yellowtops (Flaveria bidentis) is an annual herb in the family Asteraceae, native to South America, particularly Argentina, Bolivia, and Chile, but widely naturalised across subtropical and warm temperate regions worldwide, including parts of Africa, Europe, and Asia. It grows in disturbed coastal plains, roadsides, agricultural margins, and sandy soils near the coast. The plant bears clusters of small yellow flowerheads in dense corymbs, blooming from summer to autumn. Flaveria bidentis is scientifically notable as one of the few species in the genus confirmed to use C4 photosynthesis, a more efficient carbon fixation pathway typically associated with hot, arid environments. This physiological trait contributes to its competitiveness as a ruderal weed. Plants grow erect to around 1 metre, with serrate opposite leaves. It is considered a weed in some agricultural systems but poses no major conservation concerns. Its IUCN status is Not Evaluated, consistent with its ruderal, widespread, and self-sustaining nature. Research on the genus Flaveria has contributed significantly to understanding the evolution of C4 photosynthesis.