Chrysanthemums have a variety of distinctive characteristics; some species grow into tight clumps, while others grow outward. It is the distinction between blooms that led the National Chrysanthemum Society to divide them into 13 different classes according to characteristics. For example, the class one irregular incurve blooms are the giants of the genus. The petals (or florets) incurve to make a closed center, and the plant is moderately short and grown from a disbud.
Another distinction is found in the class two reflex bloom. The petals are characterized by a downward curve that overlap similarly to the plumage of a bird. The plant grows to medium height and is also grown as a disbud. Class three regular incurve blooms have incurving petals that form a globular shape, while class 4 blooms have short petals with incurving upper petals and lower petals that reflex. This plant is also short but is grown as a pot mum in addition to a disbud.
A few other distinctive characteristics that are found across classes include the small, short petals found on the intermediate curve bloom. These petals only incurve somewhat and have a more open appearance, whereas the anemone has a center that is raised like a cushion and has rays of petals around the center, giving it a considerably different look than the blooms in classes one through four.