History

• Native mesquite trees dot southwest Arizona's desert landscape, but the Chilean mesquite is an interloper that has edged its way into drought-resistant gardens. The Chilean mesquite, Prosopis chilensis, is originally from Chile, hence it's name, and it's a relative of the pea family. The thornless tree produces an edible fruit that is thought to have been eaten by native Americans, who also used the tree's fibers and pounded its seed pods into a flour.
  
  

Characteristics

• The Chilean mesquite tree has a host of desirable attributes that have made it a sought-after choice for landscaping, particularly in regions of southeastern Arizona such as Tuscon. The trees thrive in the hot sun and grow quickly, reaching up to 40 feet in height. Their grand canopy provides filtered shade and helps keep homes cool. Deemed semi-evergreen or semi-dormant, Chilean mesquites provide a swath of green in the typically brown desert landscape and require little water. These shed just some of their leaves, depending on how cool it gets. Greenish-yellow flowers appear in spring and summer, and the tree also bears edible fruit.
  
  

Care

• The Chilean mesquite tree needs the most care and attention when it's young. It needs to be watered using drip irrigation during the first year. It's easy to maintain afterward, with little or no watering required. Caution: If you do water an established mesquite tree, you can damage the wood and the root system. When the tree is young, it can be unruly and needs to be pruned and trained aggressively.
  
  

Concerns and Annoyances

• In July, seed pods of the Chilean mesquite tree drop to the ground, creating a blanket of debris, so it's best to plant these behemoth trees away from swimming pools. These trees have a shallow root system that can cause heaving on sidewalks and driveways. And Chilean mesquite trees are also vulnerable to wind damage, and entire trees can become uprooted, causing possible damage and even injury. Some advocates for planting native species of trees favor Arizona's Velvet mesquite tree over the Chilean species.