Cloves are the aromatic flower buds of the Syzyglum aromaticum tree and are commonly used as a spice or essential oil. Clove is a rich source of phenolic compounds and has higher levels than found in many fruits, vegetables, and other spices.1
References
Cortes-Rojas DF, Fernandes de Souza CR, Oliveira WP. Clove (Syzygium aromaticum): A Precious Spice. Asian Pac J Trop Biomed. 2014 Feb; 4(2) 90-96.