Also known as wild morning glory, bindweed is a climbing vine plant with an extensive root network. It is extremely difficult to get rid of and, if left unchecked, it will overrun other plants in its path, crowding and starving them to death. In Christie’s canon, this plant symbolizes corrupt morality—it’s a symbol that occurs not just in Crooked House but in Christie’s other works, including Sleeping Murder.

In an early scene, Edith points out bindweed growing in the Three Gables garden. She explains that it is a “choking, entangling” plant that kills other plants in its path. It grows mostly underground and is impossible to fully to get rid of. Like the crooked gene in the Leonides family, the plant is deep-rooted and fast-growing, causing harm to everything in its path.

As Charles watches, Edith rips up a piece of bindweed and grinds it under her heel. This foreshadows her decision to kill Josephine at the end of the novel, destroying the bad seed of the Leonides family to protect the survivors.

Edith succeeds in ridding the world of one murderer, but like bindweed, human evil is deep-rooted and insidious. The greater forces that drive murderous acts—vanity, jealousy, moral corruption, and countless others—will remain in the world, lurking below the surface.