Prenanthes

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.

P. crepidinea

2. Inflorescence cylindrical, the branches very short; leaf bases clasping the stem; basal and lower leaves oblanceolate to obovate or elliptic.

P. racemosa

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).

P. alba

3. Inner (i.e., longer) phyllaries 4–5 (–6); florets (and achenes) (4–) 5 (–6) per head; mature pappus pale brown or buff.

P. altissima