In both species, the achenes may have whitish encrustations or papillae, or may simply be smooth but for delicate horizontal striations.

1. Scales glabrous; style 3-cleft, glabrous; achenes 3-sided, ca. 0.4-0.7 mm long; anthers ca. 0.3 mm long; plant a delicate tufted annual.

F. autumnalis

1. Scales finely pubescent, at least distally; style 2-cleft, ciliate below; achenes biconvex, ca. 1-1.4 mm long; anthers 1.5-1.7 mm long; plant a hard-based, stiff perennial.

F. puberula