Chrysanthemum

Chrysanthemum is a long-lived herbaceous perennial with erect, sometimes branched stems 30–150 cm tall; leaves are alternate, deeply lobed with serrated margins and fine hairs beneath. The inflorescence is the classic capitulum of the daisy family, made of many tiny florets: outer ligulate (ray) florets form the showy petals, while a dense centre of tubular disc florets fills the head. After millennia of selection, the species has produced countless cultivars in white, yellow, pink, purple and green, with single, double, quill, spoon or fringed petals.

Cultivated chrysanthemum (Chrysanthemum × morifolium) is a long-domesticated hybrid of East Chinese origin, assembled from wild species such as C. argyrophyllum, C. dichrum, C. indicum, C. nankingense and C. zawadzkii; no truly wild population is known (Kew POWO records no native range). From China the plant spread to Japan, Korea and Vietnam and then worldwide as an ornamental and medicinal crop. China remains the main producer, with famous traditional growing regions such as Hangzhou (Hangju), Bozhou in Anhui (Boju), Huaiqing (Huaiju), Kaifeng (Bianju) and Chuzhou (Chuju).

More than 190 compounds have been identified in chrysanthemum flowers, dominated by flavonoids and phenolic acids. The two main flavonoids, luteolin-7-O-glucoside and quercitrin, account for about 85.7% of total flavonoids; apigenin, acacetin, linarin, axillarin and other apigenin derivatives also occur. Among phenolic acids, chlorogenic acid and 3,5-dicaffeoylquinic acid are the principal antioxidants, together with caffeic and ferulic acids. The essential oil contains monoterpenes and sesquiterpenes such as chrysanthenone, camphor, borneol and β-caryophyllene, which give the flowers their characteristic aroma, slight bitterness and bioactivity.

In East Asian traditional medicine chrysanthemum flowers are used to clear heat, remove toxins, brighten the eyes, lower blood pressure and ease tension; chrysanthemum tea is popular in China, Japan, Korea and Vietnam. Modern studies report that flower extracts are antioxidant, anti-inflammatory, antimicrobial, lipid-lowering and neuro- and cardio-protective in many cell and animal models. Small clinical studies suggest chrysanthemum tea may modestly lower blood pressure and improve sleep, but larger controlled trials are needed to confirm human benefits. Beyond medicine and tea, the flowers are also used in cosmetics and foods.

Chrysanthemum is generally safe in food amounts, but people allergic to pollen or sensitive to Asteraceae may develop contact dermatitis, rhinitis or mild asthma, so care is advised on first use. Chrysanthemum tea may interact with anticoagulants and blood-pressure medicines; patients on such drugs should consult a clinician, and high medicinal doses are not advised in pregnancy. Because it is a selected ornamental crop with no wild populations, chrysanthemum is not assessed as threatened by IUCN (Kew POWO records NE/not applicable for the cultivated hybrid); conservation focuses on landraces and gene banks rather than wild stands.