Southwest Desert Trees

• Many desert trees have thorns. The velvet mesquite (Prosopis velutina), blue palo verde (Parkinsonia floridum), foothills palo verde (Parkinsonia microphyllum) and Mexican palo verde (Parkinsonia aculeata) all have thorns on their branches. The whitethorn acacia (Acacia constricta), with thorns that may or may not be white, and catclaw acacia (Acacia greggii) with hooked, cat clawlike thorns, are thorny shrubs, growing to tree size when growing conditions are favorable. The netleaf hackberry (Celtis reticulata) is another desert tree with thorns, and it grows along creeks and drainage ditches where more water is available. The New Mexican locust (Robinia neomexicana) is found in the mountains of the southwest deserts, with pink to lavender flowers that droop from the ends of the branches in the late spring. The bright green leaves effectively hide thorns along the branches.
  
  

Citrus Trees

• Many citrus trees have thorns, especially the grapefruit. Grapefruit tree thorns are quite long, up to 2 inches or more. Lemons, oranges, mandarins and limes all can have thorns, but sometimes there are just a few hiding in the branches. Always be careful when you are picking fruit or pruning.
  
  

A Tropical Tree

• The floss silk tree (Chorisia speciosa) is native to South America, and has beautiful flowers, but the spikes on the trunk will certainly deter anything thinking of climbing the tree to access the blooms. It is interesting to ponder why the tree chose to have thorns on the trunk, but not on the branches.
  
  Floss silk tree has flowers that look much like a hibiscus. They are pink to burgundy in color, although C. insignis has white flowers. Chorisia speciosa "Majestic Beauty" has pink flowers, but no thorns.
  
  

Other Landscape Trees

• The black locust (Robinia pseudoacacia) is a thorny tree often used for fast shade in many parts of the country. It is native to the eastern and central United States. The black locust quickly reaches 40 to 75 feet tall and 30 to 60 feet wide. The flowers are white and fragrant. The locust, like many desert trees, is in the legume family, which allows it to manufacture its own nitrogen. This unique ability allows them to thrive in the poorest of soils.