The botanist who developed plant classifications, Linnaeus, first used the name Chrysanthemum. In 1961 the name was changed to Dendranthema to avoid confusion with other plant species labeled as Chrystanthemum. However, Mums were such a classic and popular flower that the name change created confusion and it was changed back in the mid-1990s. The Ateraceae family was once called Compositae and comprises many of our potted and garden ornamental plants. Included among these are the Mums as well as Zinnias, Dahlias and Marigolds to name but a few. All this name changing can be perplexing, but the main thing to remember is they are all in the Aster family which are generally daisy-like flowering herbaceous plants.
All blooming plants in the Asteraceae family need long days to form foliage and shorter days to promote flowering. Asters and Mums both have deeply notched soft leaves on rigid stems and the characteristic daisy-like flowers, but the differences start to mount up when you look at the two plant varieties closely. There are over 13 bloom classes of Chrysanthemum and it is a deeply cultivated and bred plant which may be perennial or annual. The bloom forms include cushion, spider, quill, spoon and pompom. Asters typically are perennials and survive to United States Department of Agriculture zone 4 while Chrysanthemums are hardy to zone 5. Mums come in a shocking array of colors from tones of orange, to red, white, pink, salmon, purple and yellow. Asters are limited to cooler hues of blue, purple, pink and white.
Chrysanthemums were cultivated in China as early as the 15th century and in Japan since the 8th century. The plant is the national flower of Japan and entire parades and festivals center around this lovely flower. The plant's cultivation moved to Europe in the 1800's and to the United States around the end of that century. Over 500 crosses were developed at this time by Elmer D. Smith who named most of these. By 1940 or so the plant really took off as a commercial specimen. Greenhouse and field growers specialized in different bloom classes and hybridization. Cultivars are classified in four ways: flower form, culture type, height of the plant and photoperiod response. A sophisticated system for classing the blooms has six levels beginning with "singles" and moving on to other forms. The final category is the "large flowered" which represent a class of 4-inch flowers. The culture type has three sections. Those that are "standards" grow from a single stem to a single flower head and are used for cut flowers. The "disbuds" have been pinched and had the lateral flowers removed to form large flower clusters usually for potted specimens. Finally the "spray" segment are grown on multiple stems with only the terminal bud removed.
Asters do not have such a loyal and organized cultural following. The blooms are the classifying feature and rely upon the number of ray florets per flower and the size to delineate to which class they belong. More than 175 species grow in the United States and the Aster is not as heavily hybridized as the Mum. Aster plants are in the genus Symphyotrichum while Mums are back again in their genus Chrysanthemum. Botanical classifications aside, both make excellent plants for the garden or home and their blooms last well into the cold season. The rainbow of colors in each species adds lively definition and tone to combined container plantings, beds, indoor pots or just as cut flowers on the dining table.