Single dahlias have blooms with a single outer ring of florets, which may overlap, the centre forming a disc |
Group 2--Anemone-flowered Dahlias Anemone-flowered dahlias have blooms with one or more outer rings of generally flattened ray florets surrounding a dense group of tubular florets, and showing no disc. 5 Top |
Collerette dahlias have blooms with a single outer ring of generally flat ray florets, which may overlap, with a ring of small florets (the Collar) the centre forming a disc. |
Group 4--Waterlily Dahlias Waterlily dahlias have fully double blooms characterised by broad and generally sparse ray florets, which are straight or slightly involute along their length giving the flower a shallow appearance. The depth should be less than half the diameter of the bloom. 5 Top |
 
Group 5--Decorative Dahlias Decorative dahlias have fully double blooms showing no disc. The ray florets are either involute, scarcely involute, not involute, or revolute at apex and either come to a point, abruptly come to a point or indented. |
Group 6--Ball Dahlias Ball dahlias have fully double blooms showing no disc, ball shaped or slightly flattened. The ray florets are displayed in spiral arrangement and are involute and round at the apex. |
Pompon dahlias have fully double spherical blooms of miniature size, with florets largely involute along their length (longitudinal axis). |
Group 8--Cactus Dahlias Cactus dahlias have fully double blooms, the ray florets are usually pointed, the majority narrow and revolute for 50% or more of their length (longitudinal axis) and either straight or incurving.
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Semi-Cactus dahlias have fully double blooms; the ray florets are usually pointed and revolute for more than 25% of their length and broad at the base and either straight or incurving. |
 
Group 10--Miscellaneous Dahlias Any dahlias which do not fall into one of the foregoing Groups e.g. Thistle Dahlias |
Fimbriated dahlias have blooms where ray florets should be evenly split or notched into two or more divisions, uniformly throughout the bloom to create a fringed overall effect. The petals may be flat, involute, revolute, straight, incurving or twisted. |
Group 12 –Single Orchid Dahlias (Star)Star or Single Orchid dahlias have blooms with a single outer ring of florets surrounding disc. Ray florets are uniformly either involute or revolute. |
Group 13 – Double Orchid DahliasDouble Orchid dahlias have fully double blooms showing no disc that have triangularis centres. Ray florets are narrowly laceolate and either involute or revolute. |
