Formal decorative dahlias
Informal decorative dahlias
Semi-cactus dahlias
Straight cactus dahlias
Incurved cactus dahlias
Laciniated dahlias
Ball, Miniature Ball and Pompons dahlias
Waterlily dahlias
Peony dahlias
Anemone dahlias
Collerette dahlias
Single and Mignon single dahlias
Orchid dahlias
Novelty dahlias
Source (photographs): François Cartier and Michèle Morency-Cartier Source (text): American Dahlia Society, Classification and Handbook of Dahlias