The Chili de Arbol is usually found in the markets dried or in powder form and it is the chili often used to make up the ristras that that popular throughout the Southwest and into Mexico (dried New Mexico chilis are also used for ristras). The name means “treelike” which refers to the plant that it grows from which can reach up to three feet in height. Nicknames for the chili include pico de pajaro (“bird’s beak”) and cola de rata (“rat’s tail”) because of the shape of the pod. It is believed that the Chili de Arbol is derived from the Cayenne chili and possibly the Piquin as well.
This pepper comes in between 15,000 and 30,000 Scoville Heat Units which puts it at a little bit higher heat level than the Serrano. I have found fresh chilis at my local international market that I believe are de Arbols or a close cousin, though they were just referred to as “hot chilis:. Those had a bit of sweetness to them and a berry-like flavor and plenty of heat. The dried version is much more common and those have a nice richness to them and a bit of smokiness and also deliver quite a kick as well.
Since the dried chili is the one you will most likely encounter, you will usually want to rehydrate those before using. Take the amount of chilis that you want, place them in a bowl, and add boiling water. Cover and let them sit about half an hour, or longer if a softer texture is desired. Be sure to reserve that liquid once the chilis are removed because it has plenty of flavor (and a kick).
I will often include the chilis in my salsas if I want to add some richness and depth to the flavor as well as kick up the heat. I also usually add them to my red chili sauce. These are also good in stews and soups as well as chili con carne, but go easy because these little firecrackers pack quite a punch. I make a salsa that features the Chili de Arbol (recipe to follow), and that is something that should only be used sparingly. But it brings plenty of flavor (along with a wallop of heat) to whatever dish it is added to. You can also make an excellent chili-garlic oil with them (another recipe to follow).
The name Chili de Arbol was recorded as far back as 1615, but it is believed that was a different chili than the one currently associated with the name. These days, they are largely grown in Mexico and shipped throughout the world. In Texas, they are often sold packaged, with Fiesta and El Mexicano as two of the popular brands. If you cannot find them in the stores near you, there are plenty of sellers online, and these ship and store quite well.