Tansy
2 of the 6 encyclopedias on this shelf carry an entry for Tansy. Both are reproduced below, so you can see where they agree and where they differ.
Collier's New Encyclopedia (1921)
a genus of Compositæ, numbering about 50 species of strong scented herbs, often shrubby below, with alternate usually much-divided leaves, and solitary or corymbose heads of rayless yellow flowers. The geyellow nus is represented represented in Europe, Eu North and South Africa, temperate and cold Asia, and North America. Common tansy (T. vulgaris) has long had a reputation as a medicinal herb, causing it to be much grown in gardens in the past. It posesses bitter, tonic, vermifuge, and febrifuge properties. The plant is a native of northern Europe, Siberia, and northwest America, and occurs in a wild state in Great Britain, but as met with along the sides of streams, etc., is often of garden origin. It now holds a place in gardens mainly for the young leaves, which are shredded down and employed to fla- TANSY vor puddings, omelets and cakes. A variety with leaves doubly curled is generally preferred.
Aiton's Encyclopedia (1910)
tan-zy, a coarse wayside plant of the composite family. It has a flat top of small yellow heads like those of a goldenrod, and dark-green cut leaves reminding one of certain ferns. It came over with the white people from Europe. Tansy thrives under wagon wheels in hard soil and dust, where it disputes the right of possession with dogfennel. The leaves contain a bitter aromatic oil. Tansy was once used as a flavoring and persistently as a household remedy for various disorders of the stomach and for muscular rheumatism. It has fallen into disfavor for culinary purposes, but it still holds a place as a remedy. The oil is a narcotic. Taken in sufficient quantity it is an active poison. See Medicine
What Has Changed in the Last Century
Collier's still recommended common tansy in 1921 as a "bitter, tonic, vermifuge, and febrifuge" herb whose young leaves flavoured "puddings, omelets and cakes"; Aiton's, more cautious in 1910, noted the oil is "an active poison." Aiton's caution won. The toxic component was identified as thujone, the same compound that made absinthe notorious, and tansy oil is no longer used medicinally or as a food flavouring in Europe and North America, where its use in food is restricted. The genus name Tanacetum has also expanded in modern botany to take in feverfew and the pyrethrum daisy, and tansy itself is now listed as a noxious invasive weed in several western US states and Canadian provinces — a long way from Collier's plant grown in gardens for its "doubly curled" leaves.
Written for this edition, 2026.