Kim et al. (1996) present preliminary evidence that all our species of Prenanthes should be placed in the genus Nabalus.
1. Involucres and pedicels conspicuously hairy; petioles of basal and lower cauline leaves conspicuously wing-margined; cauline leaves entire to toothed but only very rarely lobed.
2. Inflorescence broader, with elongated, spreading branches; leaf bases not clasping the stem; basal and lower leaves broadly triangular to ± hastate.
2. Inflorescence cylindrical, the branches very short; leaf bases clasping the stem; basal and lower leaves oblanceolate to obovate or elliptic.
1. Involucres and pedicels glabrous (or pedicels puberulent); petioles of basal and lower cauline leaves lacking wings; cauline leaves often ± deeply lobed.
3. Inner (longer) phyllaries 6–8; florets (and achenes) 8–12 (–13) per head; mature pappus dark cinnamon-brown (pappus pale when immature).
3. Inner (i.e., longer) phyllaries 4–5 (–6); florets (and achenes) (4–) 5 (–6) per head; mature pappus pale brown or buff.
All species found in Prenanthes
MICHIGAN FLORA ONLINE. A. A. Reznicek, E. G. Voss, & B. S. Walters. February 2011. University of Michigan. Web. December 17, 2017. http://michiganflora.net/genus.aspx?id=Prenanthes.