Involute petals face inwards, to the centre of the flower, and revolute flowers are outward facing.
Single Flowered: One outer ring of florets, which may or may not overlap, and make up a disc in the middle.
Anemone Flowered: One or more outer rings of ray florets (usually flattened) around a mass of tubular florets, with no visible disc in the middle.
Collarette: One outer ring of ray florets (usually flattened) that overlap, and an inner ring, or collar, of small florets, with a visible disc in the middle.
Waterlily: Wide but shallow, fully double, open blooms with wide ray florets. The depth of the bloom is not more than one third of its diameter.
Decorative: Fully double, with no visible disc in the middle. The ray florets are normally wide, and either flat or twisted, and typically have a blunt end.
Ball: Fully double, and form either a near-perfect or flattened ball. The ray florets are rounded at the tips.
Pompon/Pompom: Fully double & spherical, with florets largely involute along their length (longitudinal axis).
Cactus: Fully double, typically with pointy ray florets, most of which are narrow and revolute for over 65% of their length (longitudinal axis) and either straight or involute for the rest.
Semi-Cactus: Fully double, typically with pointy ray florets that are revolute for between 25% and 65% of their length, wide at the base, and either straight or involute for the rest.
Star (formerly Single Orchid): One outer ring of florets around the disc. All the ray florets are either involute or revolute.
Double Orchid: Fully double, no visible disc, with triangular centres. The ray florets are narrow, and all of them are either involute or revolute.
Paeony: Several outer rings of ray florets around a central disc. The florets are flat or slightly involute at the base, and the rest is flat slightly revolute.