Cinnamomum, cinnamon, is a genus of 250 to 300 or more tropical and subtropical evergreen tree and shrub species in the Lauraceae (laurel family) that are often characterized by aromatic oils in the bark and leaves. The genus includes at least five species that are used to produce the spices cinnamon and cassia, as well as essential oils, which are generally obtained from the inner bark:
1) C. verum (formerly C. zeylanicum), “true cinnamon,” or Sri Lanka or Ceylon cinnamon, which originated in Sri Lanka, and is sometimes considered to have the most delicate flavor.
2) C. aromaticum (formerly C. cassia), cassia or Chinese cinnamon, which has a stronger flavor but is less expensive, and is often sold as cinnamon; cassia accounts for most of the spice sold as “cinnamon” in the U.S.
3) C. burmannii, Korintje or Indonesian cinnamon, from Indonesia and Southeast Asia.
4) C. loureirii, Saigon or Vietnamese cinnamon, from Southeast Asia.
5) C. tamala, Indian cassia or cinnamon, from the Himalayas (Bhutan, India, Nepal, and the Yunnan province of China), which is the commonly used in Indian cooking.
The names “cinnamon” and “cassia” cause considerable confusion, as they are often used interchangeably. In the U.S., the spice produced from the dried, ground bark of any of these species is referred to as “cinnamon,” without distinguishing among species. In addition, “cinnamon” may also refer to the spice obtained from the aromatic bark of an unrelated species, Canella winterana (in the Canellaceae).
In addition to the species that are the sources of the spices cinnamon and cassia, the genus also includes C. camphora, camphor or camphor laurel, from which is derived a volatile oil used medicinally as an antiseptic and local anesthetic, as well as in respiratory inhalations.
Cinnamomum species vary in size and form--some grow to heights of 30 m (100 ft) or more, while others are smaller, 9 to 12 m (30 to 40 ft)—but all have leathery leaves with a waxy coating, generally alternate to sub-opposite but in some species opposite. Bark, branches, and leaves all contain aromatic compounds. Flowers are small and tubular, yellow or white, with 6 lobes, either unisexual or bisexual (perfect), and generally occur in axillary panicles (clusters that grow where leave join to branches). The fruit is a small, fleshy berry, partly surrounded by a cup-like perianth (developed from the outer parts of the flower).
Most Cinnamomum species originated in the Old World tropics, in Asia, the Pacific Islands, and Australia, but there are some New World species (formerly classified as the genus Phoebe) native to South and Central America, and southern North America. Several of the commercially used species are now grown in tropical areas worldwide, and have naturalized beyond their native ranges.
(Bailey et al. 1976, FAO 2012, Flora of China 2012, Hedrick 1919, van Wyk 2005.)