The National Chrysanthemum Society has developed 13 classifications to help make some sense out of the variety of flower types in the genus, Chrysanthemum.

Chrysanthemum blooms are divided into 13 different bloom forms by the US National Chrysanthemum Society, Inc., which is in keeping with the international classification system. The bloom forms are defined by the way in which the ray and disk florets are arranged.

Chrysanthemum blooms are composed of many individual flowers (florets), each one capable of producing a seed. The disk florets are in the center of the bloom head, and the ray florets are on the perimeter. The ray florets are considered imperfect flowers, as they only possess the female productive organs, while the disk florets are considered perfect flowers as they possess both male and female reproductive organs.

These are the giants of the chrysanthemum world. Quite often disbudded to create a single giant bloom (ogiku), the disk florets are completely concealed, while the ray florets curve inwardly to conceal the disk and also hang down to create a 'skirt'.

Mature ray florets usually broad and incurving over tops of bloom in a regular or irregular manner to form a very large blown with breadth and depth nearly equal. Lower florets are generally loosely incurving. No disk apparent.

The disk florets of these plants are curved downward and overlap resembling bird plumage. The tops of the blooms are full and slightly flattened. Such flowers are rather large with a diameter of 4 to 6 inches. They are narrower in proportion to their length.

This is perhaps the most popular of the mums that prosper from disbudding in the garden. The reflexed petals seem to help water run off them during rain or irrigation.

These are similar to the irregular incurve types except that these flowers tend to be smaller and form a nearly perfect globe shape with their breadth and depth are of equal size. The disk florets are completely concealed. They are also called Chinese blooms.

This form is similar to the reflex type but without the mop-like appearance. They are a more flattened bloom with short petals. The disk florets are completely concealed and the ray florets often do not radiate to more than a 90 degree angle from the stem. Each bloom is 5 inches wide or more.

This group is generally short and grown as a pot mum.

These blooms fall somewhere between Class 1 and Class 3 in both size and form. Usually, they will have broader florets and are more loosely composed. The disk florets are completely concealed.

These somewhat smaller plants are popular commercial mums. Many consider them the most elegant flowers.

These are small globe shaped flowers that are somewhat flat when they first open but totally round when they mature. They can vary in size from button shaped to up to 4 inches in diameter. Its florets incurve or reflex in a regular manner. The disk florets are completely concealed.

Unlike many other types, the disk florets are completely exposed. They have between 1 (Single) and 7 (Semi-Double) rows of ray florets which radiate not more than a 90 degrees angle to the stem. These flowers are up to 4 inches in diameter.

Disk florets are featured prominently and may be raised and overshadow the ray florets. The blooms are similar to the semi-doubles but have a raised cushion-like center. Ray florets are arranged in not more than 5 rows of equal length and evenly spaced.

This type is basically the same as the semi-doubles except that the tips of the ray florets form a spoon shape. The center of the disk is round and visible.

The disk florets are completely concealed and the ray florets are tube-like with open tips. It has an open center and the bloom is fully double.

These have long, tubular ray florets which may coil or hook at the ends. The florets may be very fine to coarse in texture. The center is not obvious.

This type of flower has fine tubular florets that grow parallel to the stem and resemble an artist's paint brush. Or, they can be in the form of a thistle with florets that are flattened, twisted and drooping.

As the name implies, these are the strange and unusual bloom types that do not fit into the other 12 classifications.