Calamus is a warm, spicy and woody-green note from the rhizome (underground stem) of Acorus calamus, the sweet flag, a reed-like marsh plant. Historically distilled into an essential oil, it smells earthy, aromatic and slightly leathery, with a sweet, powdery depth, but it is now heavily restricted in fragrance because of its β-asarone content.

What does Calamus smell like?

Calamus has an unusual mix of facets: a fresh, bitter green opening, then a warm, spicy and woody heart with hints of cinnamon-like sweetness, dry earth and soft leather. The dried root has a powdery, slightly orris-like quality that made it useful for giving body to herbal and woody blends. Crushed leaves are sweeter and greener than the root. In modern perfumes, calamus is usually a reconstructed impression built without the natural oil.

Where Calamus comes from

The plant grows in wetlands across the Northern Hemisphere. Chemistry depends on its cytotype: the diploid North American form (often classed as Acorus americanus) contains no β-asarone, while the widespread triploid and tetraploid forms can carry up to 75% β-asarone in their volatile oil. The oil was obtained by steam distilling the dried rhizome.

• Also known as: Sweet flag, flag root, sweet sedge, calamus root
• Fragrance family: Aromatic / woody
• Type: Natural (now largely replaced by reconstructions)
• Main origins: Wetlands of Asia, Europe and North America
• How it's obtained: Steam distillation of the dried rhizome
• Key aroma molecules: β-asarone and α-asarone (in most types), sesquiterpenes

Calamus in perfume history

Sweet flag has a long aromatic history. In medieval Europe the fine-cut leaves were strewn on floors for their sweet scent and to deter pests, and the root was used in liqueurs, bitters and even candy. The oil was a traditional ingredient in herbal and woody compositions and in flavourings. That changed in 1968, when the United States FDA banned calamus products as food additives because of β-asarone, and European authorities later set strict intake limits.

Calamus in modern perfumery

Because natural calamus oil is effectively off the palette, perfumers suggest it with blends of woody, spicy and green materials, sometimes with orris-like and leathery notes. Where it appears in note lists today, it is usually an evocation rather than the real oil.

How Calamus wears and what it pairs with

As a heart-to-base note, calamus gives warmth, bitterness and body with good tenacity. It pairs with vetiver, patchouli, orris, cinnamon, leather, labdanum, cedar and oakmoss.

Safety and regulation

β-Asarone, found in most calamus oils, is considered carcinogenic, and IFRA prohibits its use as a fragrance ingredient, which in practice rules out calamus oil in perfumes. It is also restricted in food flavourings in the EU and the US.