Euphorbia antisyphilitica

Also called Candelilla or Wax Plant.
Euphorbia antisyphilitica is native to Texas and southern New Mexico in the USA as well as Chihuahua, Coahuila, Hidalgo, and Querétaro in Mexico.
It is shrubby and has densely clustered, erect, essentially leafless stems that are covered in wax to prevent transpiration.

Candelilla is gaining in popularity as a landscape plant in parts of the arid southwest. It is popular for the following reasons:
• Once established it needs little water other than rainfall.
• Can survive in areas that have reflected light.
• It grows best in well-drained soils but can tolerate some clay or limestone.
• Is visited by butterflies although not commonly considered a "butterfly plant."
• It is cold tolerant to -9°C.
• It appears not to be bothered by pests.
• Can be grown in containers.