The chile de arbol is pronounced: cheel ay day ar boll. Chiles de arbol are narrow, curved chiles that start out green and mature to bright red. The arbol chile is very hot, and related to cayenne pepper. Be careful during preparation. Arbol chiles are also the ones that are dried after turning red and used in many holiday wreaths.
The Chile de Arbol rates between 15,000 and 30,000 Scoville units on the heat index.