Broad-leafed trees in a temperate zone lose their leaves to survive the extreme temperatures of summer to survive a lack of rain in the dry season to survive colder seasonal temperatures to allow for greater penetration of sunlight

Broad-leaf trees deep their leaves in colder seasonal temperatures.

Trees with broader leaves usually drop their eaves during winter season to protect them from cold temperatures. It helps them to protect from leaf freezing because leaf freezing can lead to no energy production.  

In some plants, in order to bear cold temperatures, plants develop a thick, waxy coating on each needle which protects against the cold weather.

Some examples of deciduous trees are given: Blue spruce, Eastern white pine, Oak, Elm etc

the denominator has a very specific role.

answer; coat color for blending in with dry grass;