
Cinnamon stick is the dried inner bark of trees of the genus Cinnamomum, rolled into a tubular quill and used whole as an aromatic spice.
Warm, sweet-woody aroma driven by cinnamaldehyde, over a mild bittersweet bark flavour; long infusion draws out a faint tannic, woody edge.
A whole stick releases its flavour slowly, so it is infused into a hot or warm liquid, syrup or spirit rather than dropped into a cold drink, where the intact quill gives up little. It serves as a background aromatic or the defining note of a spiced syrup, and doubles as a garnish; Ceylon quills are soft enough to crumble or grind, whereas cassia sticks stay hard and woody.
For a background warm note, ground cinnamon or a cassia stick of a related Cinnamomum species reproduces the aroma, differing only in infusion speed and clarity; an unrelated warm spice such as clove or nutmeg cannot stand in, because the specific cinnamaldehyde aroma is the whole point.
Cassia bark
Ceylon cinnamon (C. verum) is thin-layered, crumbly, more delicately aromatic and very low in coumarin; cassia (C. cassia and related species) is thicker, harder, more pungent and markedly higher in coumarin. Both are sold generically as "cinnamon" in stick form.
Strips of the dried inner bark curl as they dry to form the hollow tubes called quills. "Cinnamon" covers several Cinnamomum species: true or Ceylon cinnamon (C. verum) is made from only the thin inner bark, forming many delicate layers that are lighter and crumbly, while the cassia types (including Chinese, Vietnamese, Indonesian and Malabar cinnamon) use thicker bark, typically 2–3 mm, and are harder and woodier. The characteristic scent comes largely from cinnamaldehyde in the bark's volatile oil, and cassia carries substantially more coumarin than the trace amounts found in Ceylon cinnamon.
True (Ceylon) cinnamon, Cinnamomum verum, is native to Sri Lanka and neighbouring South Asia, including India and Myanmar.