Chile size is 2 to 3 inches long x 1/4-inch, maturing in 75 to 80 days. Chili de Arbol blends fiery heat with smoky flavors that really enhance Mexican cooking. Plants reaching up to 4 feet tall bear heavy loads of slender, curved peppers all summer long. The Chile de árbol (Spanish for tree chili) is a small and potent Mexican chili pepper also known as bird’s beak chile. Their heat index is between 15,000 and 30,000 Scoville units. Wear gloves when preparing. The peppers start out as green and mature to red. Arbol chiles are best used in small doses, and can be used in salsas, chili or sauces.