What is their precipitation like? Also, what exactly do you mean by "tropical" (big leaves?, everygreen? color?...) Zone 8 really isn't tropical but if your looking for a "tropicalesque" look, you might also consider posting this on the "tropicalesque" forum.

Hi - Thank you. tina_2

I'm not sure what this is called but it looks good and is evergreen

A Sunshine Mimosa stays green, blooms with pompom-like flowers and supposedly can be grown in zone 8.