The genus once included many more species, but was split several decades ago into several genera; the naming of the genera has been contentious, but a ruling of the International Code of Botanical Nomenclature in 1999 has resulted in the defining species of the genus being changed to Chrysanthemum indicum, thereby restoring the economically important florist's chrysanthemum to the genus Chrysanthemum. These species were, after the splitting of the genus but before the ICBN ruling, commonly treated under the genus name Dendranthema.
The other species previously treated in the narrow view of the genus Chrysanthemum are now transferred to the genus Glebionis. The other genera split off from Chrysanthemum include Argyranthemum, Leucanthemopsis, Leucanthemum, Rhodanthemum, and Tanacetum.
The species of Chrysanthemum are herbaceous perennial plants growing to 50-150 cm tall, with deeply lobed leaves and large flowerheads, white, yellow or pink in the wild species.
Chrysanthemum species are used as food plants by the larvae of some Lepidoptera species - see list of Lepidoptera which feed on Chrysanthemum.
Today’s flowers are not as bright or large as ‘show’ varieties.
Chrysanthemums were cultivated in China as a flowering herb as far back as the 15th century BCE. An ancient Chinese city was named Ju-Xian, meaning "chrysanthemum city". The flower was introduced into Japan probably in the 8th century CE, and the Emperor adopted the flower as his official seal. There is a "Festival of Happiness" in Japan that celebrates the flower.
The flower was brought to Europe in the 17th century. Linnaeus named it from the Greek prefix chrys-, which means golden (the colour of the original flowers), and -anthemon, meaning flower.
Modern chrysanthemums are much more showy than their wild relatives. The flowers occur in various forms, and can be daisy-like, decorative, pompons or buttons. This genus contains many hybrids and thousands of cultivars developed for horticultural purposes. In addition to the traditional yellow, other colours are available, such as white, purple, and red. The most important hybrid is Chrysanthemum × morifolium (syn. C. × grandiflorum), derived primarily from C. indicum but also involving other species.
Modern chrysanthemums are much more showy than their wild relatives. The flowers occur in various forms, and can be daisy-like, decorative, pompons or buttons. This genus contains many hybrids and thousands of cultivars developed for horticultural purposes. In addition to the traditional yellow, other colours are available, such as white, purple, and red. The most important hybrid is Chrysanthemum × morifolium (syn. C. × grandiflorum), derived primarily from C. indicum but also involving other species.
Chrysanthemum leaves resemble its close cousin, the mugwort weed -- so much so that mugwort is sometimes called wild chrysanthemum -- making them not always the first choice for professional gardeners.
Chrysanthemums make a welcome addition to the garden, in particular because their late flowering offers advantages when the other garden plants are winding down for winter. Outdoor flowering chrysanthemums will need protection from hard frosts.
