1	"Plants spiny and thistle-like"	Dipsacus
1	"Plants not spiny"	2
2	"Involucral bracts hard, overlapping, in several rows"	Cephalaria
2	"Involucral bracts soft, in 1–2 rows"	3
3	"Calyx of 5 bristles"	Scabiosa
3	"Calyx of 10 bristles"	Pterocephalus