Answer: The first step to getting your garden to thrive in heat and dry condition (which I assume you have) is to make sure your beds have plenty of organic matter before planting. After planting, cover the beds with several inches of organic mulch such as shredded leaves, clean straw or compost.
Here are a few suggestions for plants that withstand hot, dry, sunny conditions; contact your local county extension office (918-746-3700) for a more extensive list of plants for your region. Shrubs: Amorpha fruticosa (false indigo), Potentilla fruticosa (shrubby cinquefoil), and Rosa rugosa (rugosa rose); perennials: Achillea millefolium (common yarrow), Gaillardia grandiflora (blanketflower), and Liatris (gayfeather).
Also, here are several references that might be of some help:
The Undaunted Garden by Lauren Springer
The American Horticulture Society's Heat Zone Gardening by Henry Cathey and Linda Bellamy
The Low-water Flower Garden by Eric Johnson
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