In botany, an evergreen plant is a plant having leaves all year round. This contrasts with deciduous plants, which completely lose their foliage for part of the year. Some perennial species retain their foliage all year round; these are evergreen perennials.
One of the best features of evergreen perennials is the visual interest they provide when left standing over the winter. During winter months, many perennials provide winter interest in the garden. There are many varieties of evergreen perennials, the following are a few you may want to consider: Ajuga (Bugleweed), Arabis (Rock Cress), Armeria (Common Thrift, Sea Pink), Bergenia (Heartleaf Bergenia, Pig Squeak), Carex (Sedge), Dianthus (Pinks), Euonymous f. 'Colorata' (Purple Leaf Wintercreeper), Festuca (Blue Fescue), Hedera (English Ivy), Helictotrichon (Blue Oat Grass), Helleborus (Lenten Rose), Heuchera (Coral Bells), Heucherella (Foamy Bells), Iberis (Evergreen Candytuft), Lavandula (English Lavender), Liriope (Lily-turf), Pachysandra (Japanese Spurge), Phlox subulata (Creeping Phlox), Sagina (Irish Moss), Sedum (Stonecrop--some, mostly low-growing groundcover types), Sempervivum (Hen & Chicks), Thymus (Creeping Thyme), Tiarella (Foamflower), Vinca (Myrtle, Periwinkle), Yucca (Adam's Needle).
The follow plants are evergreen in our zone 7, many may be evergreen through out the country, some may be semi-evergreen 'down the street'.