(November 2016) Pogona is a genus of reptiles containing eight lizard species, which are often known by the common name bearded dragons. The name bearded dragon refers to the beard of the lizard, the underside of the throat which turns black if they are stressed or see a potential rival.
Desert willow (Chilopsis linearis), with its delicate, pale green leaves and large, fragrant flowers, loses its leaves in winter. A North American native, desert willow grows wild in the southwestern United States and Mexico. It commonly grows in desert areas that flood seasonally, like stream beds and low canyon areas.
There'll be outlier trees-- I've seen sick trees drop their leaves in August, and leafed deciduous trees in January as far north as Manhattan-- but there's a clear peak. In tropical climates, there's more variation in when the trees drop their leaves: it has to do with wet and dry seasons, soil quality, wind and elevation. To get a view that looks like autumn in Mexico, for example, you have to go into the mountains.