Chaste tree or
Vitex agnus-castus originally from China but growing in your area since 1670. Very drought tolerant.
"Blooms from late spring until early fall with long, upright spikes of pink, lilac and white flowers. Any shrub or tree that blooms all summer is well worth planting, but when it also has pleasantly fragrant flowers and foliage, it becomes a must-have plant. Chaste tree garden care is easy, but there are a few care essentials you need to know to get the most from this outstanding plant.
Chaste trees need full sun and very well-drained soil. It’s best not to plant them in soil that is rich in organic matter because organically rich soils hold too much moisture close to the roots. Chaste trees do very well in xeric gardens where water is scarce. Once established, you’ll probably never have to water a chaste tree. Inorganic mulch, such as pebbles or stones, allows the soil to dry between rains. Avoid using organic mulches such as bark, shredded wood or straw. Fertilize the plant every year or two with general-purpose fertilizer."
Read more at Gardening Know How: Chaste Tree Info: Tips On Chaste Tree Cultivation And Care
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I planted one in my yard.
Also,
Lupinus texensis or Texas Blue Bonnet would be an easy flower to grow in your area as well.