Costmary (Alecost): The Balsam-Scented Herb Once Used to Flavor Ale

Why would an herb be called “Bible leaf”? People reportedly pressed costmary leaves in Bibles as bookmarks, and its other old name, alecost, comes from English brewers flavoring ale with it. Costmary (Tanacetum balsamita) is a perennial herb in the aster family, with long leaves that smell of mint and balsam. These days it’s mostly a garden curiosity, but the leaves still work as a seasoning for meat and a sharp note in salads.

At a glance

What costmary is

Costmary is an aromatic perennial in the aster family with yellow, button-shaped flowers. It’s a perennial or rhizomatous geophyte of temperate climates and was once common in herb gardens.

Despite the name “mint geranium,” it’s neither a mint nor a geranium. Its botanical name has moved around, too: Kew accepts Tanacetum balsamita and lists Balsamita major and Chrysanthemum balsamita among its synonyms.

The name

Merriam-Webster traces “costmary” to Middle English costmarie: coste, from Latin costum and Greek kostos, a fragrant root, plus Marie, the Virgin Mary. The word shows up in English from the 15th century. NC State Extension mentions one possible reason for the Mary connection: the herb may have been used in medieval times to ease pain in childbirth. It offers that as a possibility, not a fact.³

Flavor and aroma

Sources describe the leaves differently. Britannica calls them bitter and slightly lemony.⁴ NC State Extension gives them a minty balsam scent,³ and Wakefield’s museum service says they give off a distinct balsam or minty smell when crushed.⁵ Think of it as a minty, resinous herb with a bitter edge, closer to sage than to garden mint.

The compounds

Costmary doesn’t have one chemical profile. A 2022 study notes four chemotypes reported for the species: carvone, camphor, camphor-thujone and carvone-α-thujone types.² Its own samples, collected in Serbia’s Ovčar-Kablar Gorge, were the carvone type:²

Carvone is also the main component of spearmint oil. These figures describe one population, so don’t read them as typical of all costmary.

Where it comes from

Kew gives the native range as the eastern Mediterranean to Crimea and Iran, listing Cyprus, Iran, Iraq, Crimea, the Transcaucasus and Türkiye.¹ NC State Extension says southern Europe and western Asia.³ Kew records it as introduced across much of Europe and in many US states and Canadian provinces.

You may see a story that costmary began on the Indian subcontinent. We couldn’t trace it, and Kew’s range doesn’t include it.

History

• Ale. NC State Extension says the name alecost comes from the English use of the herb to flavor ale. Wakefield’s museum service adds that before hops caught on, alecost was used to clear, flavor and preserve beer and ales.⁵
• Tudor households. It was a popular strewing herb in Tudor times, according to the same museum service.
• Bible leaf. Alecost leaves were sometimes used as bookmarks in Bibles. NC State Extension reports that American colonists did this, and that the scented leaves helped keep churchgoers awake through sermons.³ Both sources frame this as tradition.

You’ll also find claims that Theophrastus recorded Greek use of costmary in perfume, that it reached England in the 1500s, that Culpeper called it the balsam herb and prescribed it for phlegm and ulcers, that French cooks put it in soups, and that it repelled silverfish. We couldn’t trace any of those to a source we could open, so we’re not repeating them as fact.

How to use costmary

• Meat and poultry. Britannica lists meats and poultry among the foods costmary flavors, fresh or dried. Wakefield’s museum service records it being cooked as a substitute for sage or mint.⁵ It should suit fatty meats where you’d use sage.
• Salads. You can use the leaves fresh in salads. They’re strong and bitter, so pick young leaves and chop them fine.
• Soups. NC State Extension lists soups among its uses.
• Tea and potpourri. The dried leaves go into tea and potpourri.
• Preserves. The flower petals can go into conserves.
• Brewing. Costmary is still tied to beer: a 2022 study lists beer flavoring among its traditional uses.²

It can stand in for mint in iced tea or fruit salad, but expect a more resinous, bitter result than mint. See also mint substitutes and sage substitutes.

Buying and storage

We found no published shelf-life figure for fresh or dried leaves.

Health and safety

Costmary has a long folk-medicine history, and a 2022 paper notes it was classified as a laxative and astringent.² The research we found is all lab work. That same paper tested its essential oils on cancer cell lines and on bacteria in apple and carrot models, which tells you nothing about eating the herb.²

You’ll see claims that costmary treats bronchitis, water retention, intestinal worms or childbirth pain, or that its flavonoids, minerals and glycosides protect against heart disease, cancer or diabetes. We couldn’t trace any of them to a source, and we’re not claiming costmary treats or prevents any condition.

NC State Extension flags the plant as a problem for dogs, cats and horses without saying why.³ Some costmary oils contain α- and β-thujone (above).² We didn’t find a regulator’s assessment of thujone intake from costmary specifically, so we can’t say whether culinary amounts matter.