What Does "Winter-Deciduous" Mean?

 Other terms used besides Winter Deciduous include semi evergreen. It just means when it gets cold enough, it might drop its leaves because they get damaged by freezing weather, In warmer climates than Las Vegas, or if Las Vegas gets a winter with little to no freezing temperatures, then the leaves aren't damaged by the cold and they don't get damaged or may not drop. 

A change in leaf color to a "bronzing" yellowish brown can also occur. This is also a signal that it got cold. 

To reduce the chance of freezing damage, stop applying fertilizers to plants by around July 1.

This winter air temperature became so cold in this North Las Vegas location that this mesquite tree leaves were damaged, but not the tree, and they dropped. This tree, sometimes also called semi-evergreen, became deciduous.

If it gets cold enough, plants like this Star Jasmine will get yellow or bronze leaves and may even get deciduous.

Sago palm can also get cold damage during the winter if temperatures get low enough.

Bottlebrush can also get damaged from cold if winter temperatures are low enough.

Cold or freezing damage can also occur to some plants like this myoporum (locally called Australian Racer). It depends on how cold it got and for how long.