You need to post this over on the Texas Gardening Forum. There will be lots of people over there with good suggestions.

Vines that can be trellised or trained up are always an interesting option for small spaces. I really love my Confederate Jasmine, an attractive controllable vine with shiny evergreen leaves and very fragrant creamy white flowers. It does very well in hot humid Georgia so it should be okay in Texas.

You might also think of fragrant blooming herbs like Rosemary or Lavender, both heat and drought tolerant and even the foliage is fragrant if brushed.

Dianthus
Monarda
Lilies (Oriental & Ginger)
Scented Geraniums
Phlox