Simple, the bristles all of the same sort.
Heads few-flowered, themselves aggregated into a compound or dense cluster 1
Heads separate, few-flowered or many-flowered.
Receptacle (when the flowers are pulled off) bristly-hairy 78, 79, 80
Receptacle deeply honeycomb-like 81
Receptacle naked.
Pappus of plumose or bearded stiff bristles. Flowers purple 8
Pappus of very plumose bristles. Flowers whitish 6
Pappus of slender but rather stiff rough bristles 4, 5, 7, 9, 16
Pappus of very soft and weak naked bristles 76, 77