Poison source in Agatha Christie's "A Pocket Full of Rye"

YEW

This evergreen’s toxic berries and needles have been used for both arrows and deadly tea.

In Agatha Christie’s A Pocket Full of Rye, the poison used in the murder comes from the yew tree, a plant known for its toxic seeds and leaves. The clue points directly to this real-life danger, as yew has long been associated with poisonings in history and literature. The answer is simply "YEW," referencing the tree that provides the deadly substance in the story.