Hello, This has been unclear to me for some time now: Can someone please help me understand the difference between evergreen perennials and deciduous perennials? Here are my 3 questions: 1) I thought all perennials would be considered "deciduous" since perennials die back (essentially disappear underground) during dormant seasons (fall and/or winter)....is that a correct statement? 2) Would sub-shrubs such as lavender be considered evergreen perennials? If so, why? What do sub-shrubs (such as russian sage, lavender, thyme etc.) look like in the dormant seasons in the Pacific Northwest? 3) What is the definition of an evergreen perennial and how does it compare to the definition of a deciduous perennial? And what about semi-evergreen perennials? And how do these definitions relate to the definition of a sub-shrub? Thank you.