The leaves of plants in a chaparral

are covered with sticky resin

Explanation:

The chaparral can be found in the southwestern part of the United States and in the northwestern part of Mexico. It is perfectly evolved for surviving in hot and dry conditions. In order to be able to survive in the hot and dry environment, as well as protect itself from the herbivores, the chaparral has managed to develop an excellent adaptation that serves for multiple purposes. The leaves are covered in sticky resin. This sticky resin is able to screen the leaves against the ultraviolet radiation. It also manages to stop the loss of water, as well as putting away the herbivores as they find it toxic and disgusting.

answer; in the disk but not the halo;