The Chile de árbol Spanish for tree chili is a small and potent Mexican chili pepper also known as s beak chile and rat s tail chile These chilis are about 5 to 7 5 cm 2 0 to 3 0 in long and 0 65 to 1 cm 0 26 to 0 39 in in diameter Their heat index is between 15 000 30 000 Scoville units The peppers start out green and turn a bright red color as they mature …