Paris quadrifolia

This odd little woodland flower, related to the trillium, is a native of the UK. Whereas trilliums are based on threes (three petals, three leaves), Paris is based on fours (four petals and four leaves). The name Paris has nothing to do with the city, rather comes from the Latin word par (equal) for the balanced pairs of leaves.

Because of its tidy symmetry, it was used in medieval times to ward off witches and in marriage counseling. It bears a single blue fruit, very bitter and poisonous, though it was used as an antidote to mercury and arsenic as well as an aphrodisiac.