Home Gardening Center Tip Sheet: Chrysanthemum ClassificationBy Sonia Uyterhoeven
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For more on chrysanthemums see: Chrysanthemum: History and Flower Form.
Chrysanthemums (Chrysanthemum) are composites, meaning that their flower heads are made up of tiny individual flowers. The flowering parts of chrysanthemums are made up of disk and ray florets.
Disk florets are tiny flowers located at the center of the bloom; ray florets are the showier flowers on the perimeter (what we view as the petals). There are 13 different classes of chrysanthemums with varying flower forms defined by the National Chrysanthemum Society, as described below.
Chrysanthemums are used in a variety of ways. There are chrysanthemums that are specifically hybridized for cut flowers. Garden mums are generally bred to be cold hardy, compact, and floriferous.
Classifications of the National Chrysanthemum Society
Class 1: Irregular Incurve
These are the giant blooms in the chrysanthemum world. Many of the chrysanthemums in the ogiku or single stem display come from this class. Some of the ozukuri or 'Thousand Bloom' come from this class as well. The florets are loosely incurved, meaning that they curve upward and fold into the center of the plant. The lower florets on the flower fall in an irregular pattern giving the bloom a skirted look. Many of the flowers in this category are 6 to 8 inches across.
Class 2: Reflex
In this category the florets curve downward. The tops of the blooms have a somewhat flattened appearance when they are fully open. Some people describe the flowers as having a mop-like appearance. Others say that the way the florets tend to overlap make the flower look like plumage on a bird. These flowers are not as large as Irregular Incurve but they can still span 4 to 6 inches in diameter.
Class 3: Regular Incurve
For those who like symmetry and order, this is your category. The florets form a nice round bloom that forms a ball. This category used to be named "Chinese." The flower size can reach up to 4 to 6 inches in diameter.
Class 4: Decorative
This is a very common class of mums. You will often find this shape in garden mums. The flowers have a flattened shape compared with the first three classes. The florets tend to be short. Upper florets generally are incurved (curl up) and lower florets tend to be reflex (bending down). You will find this class of chrysanthemum in a kengai or cascade display.
Class 5: Intermediate Incurve
This popular class is smaller than the Irregular Incurve, with shorter, partially incurving florets and a more open appearance. It looks like a hybrid between Irregular Incurve and Regular Incurve.
Class 6: Pompon
These chrysanthemums have a small, globe-like bloom that is flatter when young and becomes round as it ages. The florets are either incurved or reflex in a regular fashion. The flower size can range from 1 to 4 inches.
Class 7: Single and Semi-Doubles
This is the quintessential daisy-shape bloom that you see in many members of the Asteraceae family. A central section of disk florets is surrounded by several rows of ray florets (generally between 1 and 7 rows). You will find this class of chrysanthemum in kengai or cascade displays.
Class 8: Anemone
The flowers in this class are similar to Semi-Double chrysanthemums except that they have a raised center that looks like a pincushion. You will find this class of chrysanthemum in kengai or cascade displays.
Class 9: Spoon
The long, tubular ray florets in this class are spatulate, meaning they look like a spoon. The central disk in this flower is round and visible. It looks very similar to Semi-Double except for the fact that the ray florets (outer petals) look like spoons.
Class 10: Quill
The blooms in this class are fully double with no open center. The florets are straight and tubular with open tips that look like quills.
Class 11: Spider
This class has long tubular ray florets that hook or coil at the end. The florets can be fine or coarse. The florets fall in a loose mass and look like they have barbs on their ends. Intricate spider mums look like firework displays.
Class 12: Brush and Thistle
These chrysanthemums either look like an artist's paint brush or a thistle. In the brush form the fine tubular florets grow in an upright fashion, while in the thistle form the florets twist all around the stem or fan out in a horizontal manner.
Class 13: Unusual
These are the blooms that do not fit into any other class. They can be very exotic with twisted florets. The Edo varieties that you can see in shino-tsukuri or driving rain displays are often from this category. Some of the ozukuri or 'Thousand Bloom' come from this class. Notice that the florets can be flat, spoon-like, or quill-like. Members of this class often take on characteristics of several of the classes.
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