1	"Perianth-segments or lobes 6, unequal"	2
1	"Perianth-segments or lobes 5, almost equal"	3
2	"Three outer segments small, 3 inner ones large"	Rumex
2	"Three outer lobes spiny, 3 inner ones smaller"	Emex
3	"Flowers mostly bisexual"	Polygonum
3	"Flowers unisexual"	Muehlenbeckia