Species of Euthamia seem far from distinct, and more work is needed despite the small size of the genus.

1. Principal cauline leaves with 1 strong longitudinal vein (i.e., the midrib) and sometimes with a pair of weak veins, the widest blades less than 3 (-3.5) mm broad; leaves and upper part of stem glabrous; uppermost leaves and leafy bracts glistening as if varnished and with conspicuous, dense, dark glandular dots.

E. caroliniana

1. Principal cauline leaves with 3 strong longitudinal veins, the widest blades (3-) 3.5-8 (-13) mm broad and often with an additional pair of weaker veins; leaves and upper part of stem usually short-hairy to scabrous-hispidulous; uppermost leaves and leafy bracts dull in aspect, the glandular dots often obscure.

E. graminifolia