1	"Plant a small woody tree to 9 m tall"	"Dahlia imperialis"
1	"Plant a herbaceous shrub to 2 m tall"	2
2	"Leaflets to 5 cm long; capitula to 5 cm across"	"Dahlia merckii"
2	"Leaflets more than 5 cm long; capitula more than 5 cm across"	3
3	"Leaves usually deeply divided with 3–5 segments; flowers mostly pale purple"	"Dahlia pinnata"
3	"Leaves simple, or compound; flowers various, usually brightly coloured"	"Dahlia ×hortensis"