Strictly speaking, a "perennial" plant is one that lives at least three years. There are "woody perennials" (trees and shrubs) and "herbaceous perennials" (plants that mostly die back to the ground at the end of the growing season).
In common garden lingo "perennial" plants are, in fact, herbaceous and include favorite garden flowers such as peonies, daisies, irises, hostas and many, many others. And, it's herbaceous plants that you'll find links to along the right side of this page.
You may find it interesting and/or encouraging (or not) to learn that until the late 1980's I had absolutely no interest in, nor knowledge of herbaceous ornamental perennial plants.
That all changed in March of 1989, when I attended a single, one hour slide presentation by Eric Groft, a landscape architect with the renown Washington, D.C. landscape architecture firm Oehme, van Sweden & Associates, Inc. His slides of landscapes filled with huge masses of colorful perennials and swaying ornamental grasses absolutely captured my attention and imagination.
Since the end of that one hour presentation, I've spent countless hours reading about perennials, learning about how they grow and look at different times of the year in numerous botanical gardens and arboreta and, of course, growing them in my own garden as well as those of my clients!
If you'd like to learn more about perennials and how they can be used in your landscape and garden, three relatively nearby collections include the Peony and Sun Perennial Garden at the Cornell Plantations in Ithaca (photo at the top of the page), the Oehme, van Sweden & Associates-designed Friendship Garden at the National Arboretum in Washington, D.C. (photo in the center of the page), and the Idea Garden perennial border at Longwood Gardens in Kennett Square, Pennsylvania (photo at right, above).
I hope that you'll find as much enjoyment in learning about - and growing these plants as I have!