The most notable of these is O. crocata, which lives in damp, marshy ground, and resembles celery with roots like a bunch of large white carrots.

The name "Oenanthe" was used in ancient times to refer to several different plants, one of which was described by Pedanius Dioscorides[7] as having "white flowers... and many round heads."

[9] Although the word is ultimately derived from the Ancient Greek οίνος, "wine" and άνθος, "flower", this has no meaning when applied to the water-dropworts other than as an arbitrary name for the genus.

[12] As of 2020[update], Kew's Plants of the World Online accepts 33 species of Oenanthe:[1] The following simplified key can be used to distinguish the six British water-dropworts, by eliminating them one by one.

No bracts, upper leaves with narrow segments, petiole solid, rays not thickening in fruit... O. lachenalii Scientists at the University of Eastern Piedmont wrote that they had identified hemlock water dropwort (Oenanthe crocata) as the plant responsible for producing the sardonic grin.

It was purportedly used for the ritual killing of elderly people and criminals in Nuragic Sardinia, in which they were intoxicated with the herb and then dropped from a high rock or beaten to death.