Answer: The site you describe may only support a few very heat-tolerant plants. The first that comes to mind is Cotoneaster. While it's generally considered a shrub, its natural arching shape makes it perfect for training onto a trellis attached to a wall. As an espalier, it's quite attractive with small, deep green foliage and bright orange berries. Cotoneaster is evergreen, so it will look nice all year around. Some suggestions for smaller shrubs and groundcovers include Hypericum (St. John's Wort), Genista (dwarf broom), Hebe, Juniper, Heather, Erigeron, Echeveria, Euphorbia and Cistus (rockrose).
For even more ideas, check out a copy of Sunset Western Garden Book (available in libraries, book stores and garden centers. In addition to listing and describing hundreds of plants, there are lists of plants suitable for dry sites, sunny sites, rock gardens, shady sites, etc. I'm sure you'll find it helpful.
Hope the above suggestions help you make your garden design stunning!
Q&A Library Searching Tips