Hawthorn

Hawthorns are plants belonging to the genus Crataegus. Associated with Faerie, is considered deadly to vampires and it is thought unlucky to cut a plant down at anytime other than when it is in bloom.

Cold Days
In Cold Days, the Redcap hits Harry Dresden with a hawthorn dart, causing a bleeding wound that does not easily heal. According to Kringle, hawthorn burns hot and does not care for Winter Faerie.