An Herb to Know: Costmary

Costmary is an herb of many names. Its principal common name shows it to be an herb dedicated to the ­Virgin Mary. The alternate name sweet Mary likely refers to the Virgin Mary, too, or it could refer to Mary Magdalene: the early herbalists Gerard and Culpeper mentioned an herb called maudlin (Magdalene) which was identical or very similar to costmary.

Other common names for costmary allude to its uses. As a flavoring of ales and spiced wine, it was called alecost. The name allspice applied to this herb may be a variant spelling for ale-spice, or perhaps the herb’s scent reminded someone of the spice allspice. Mace, an old name from Lincolnshire, could have a similar root. Sweet tongue, a common name in Maine, refers to both the taste and the shape of the leaves.

The large, oblong leaves of costmary make neat, fragrant bookmarks, a use which spawned the old names Bible leaf or Bible plant. The minty odor, which persists in the dried leaf, might repel silverfish or book lice from the family Bible, and the leaf could be sniffed surreptitiously during long sermons to maintain wakefulness.

Mint geranium is a misnomer: costmary is closely related neither to the mints (Lamiaceae/Labiatae) nor to the geraniums (Geraniaceae), there’s no­thing geraniumlike about its appearance or odor, and it is minty only in smell and taste. Another name referring to its odor is balsam herb. To add to the confusion, the name costmary has also been applied to tansy (Tanacetum vulgare), to which our Herb to Know is closely related.

The scientific names of costmary seem as slippery as the common ones. Long known as T. balsamita and before that as Balsamita major or B. mas, costmary more recently has appeared widely as Chrysanthemum balsamita or as C. b. var. tanacetoides. The latest word — that of the highly respected four-volume New Royal Horticultural Society Dictionary of Gardening (1992) — is that it’s T. balsamita once more, but the companies listed as sources below all know it as C. balsamita.

DESCRIPTION

Stiff, leafy stalks of costmary rise from spreading rhizomes. The upward-pointing, silvery-hairy, pale green leaves with fine, rounded teeth may measure as large as 12 by 2 inches. Lower leaves are stalked and large, the upper ones stalkless and progressively smaller. The flowers, in clusters of tiny yellow buttons at the top of 3-foot stalks, bloom in very late summer in northern climates, not at all if plants are grown in shade. Plants whose flowers have minute white ray flowers used to be classified as C. balsamita, whereas those with no ray flowers (just yellow disk flowers like those of tansy) were assigned to var. tanacetoides (which means “like tansy”). Ger­trude B. ­Foster, in Herbs for Every Garden (1966), noted that the former has a camphor scent and the latter a mint scent. Madalene Hill and Gwen Barclay, in Southern Herb Growing (1987), found the scent of C. balsamita reminiscent of wintergreen, and that of a cultivar, C. b. ‘Camphor’, to be “the clean, crisp aroma of camphor.” When shopping for a costmary plant, therefore, sniff and compare. And don’t just press fresh costmary leaves in the family Bible; first dry potential bookmarks between layers of blotting paper or clean newsprint, in a flower press or under a heavy weight, so that the leaves of the book don’t warp or become discolored.