Answer: Yes, all morning glory species (Ipomoea) are labeled as "noxious weeds" and thus illegal, except I. carnea (Mexican bush morning glory ), I. triloba (three-lobed morning glory, which is a still labeled as a restricted pest) and I. aborescens (morning glory tree).
There are a variety of excellent reasons for prohibiting plants labeled as "noxious weeds" such as they can spread rapidly, don't have native controls, and drive out native plants. For an excellent article on this topic from the University of Arizona, access http://cals.arizona.edu/extension/ornamentalhort/plantprotec...
Some other vines that I enjoy that do well in sun and heat are Queen's Wreath, Trumpet Vine, and Cat's Claw. There are also many heritage rose vines that thrive.
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