Why are trichomes important for both the roots and shoots of plants?
Plant leaf hairs, or trichomes are vital for many reasons.
Interestingly in 1975 researchers were correct when they stated:

&quot;It can be argued that essentially the same genetic system should be required for both root hairs and trichomes.&quot; [1](Pay-wall)

For example:

C. salvifolius, there are more adaxial trichomes present to avoid UV light from injuring the abaxial surface.[2](Pay-wall)
Increased transpiration [3](Pay-wall)
Protecting against insect herbivores [4](Pay-wall)
Increasing tolerance to freezing [5](Pay-wall)