Southeastern Arizona boasts a wonderful diversity of native morning glory vines of the genus Ipomoea, with a total of twelve species. Of these, three have national and state conservation/rare status.
Ipomoea plummerae is a regional endemic that is a National Forest Service species of concern. I. longifolia is a state listed rare plant (S2 state conservation status) and Forest Service species of concern. And I. thurberi is a state listed very rare plant (S1 state conservation status), and a nationally listed very rare plant (N1 national conservation status). Ipomoea thurberi is currently found from five localities in the wild in the United States - all of which are from Santa Cruz County in southeastern Arizona. The actual designation for a N1 listed plant is “very rare/critically imperiled,” being from less than six localities in the wild. Despite the rare status of these native plants, the Arizona Department of Agriculture has determined that they are noxious weeds. Essentially this means that these plants are banned from sale in Arizona. It is highly unfortunate that known invasive plants like Fountain Grass, Bermuda Grass, Tamarisk/Salt Cedar, Tree of Heaven and African Sumac are all legal to grow and sell, but not these beautiful, native plants.
The Arizona Department of Argriculture’s decision may be based on experience with a non-native plant (Convolulus arvensis - field bindweed which is in the Morning Glory Family, Convoluvlaceae) that has been known to be invasive in irrigated areas. It seems more plausible that this fear of native Ipomoea species comes from an invasive hybrid of two native species known from the east coast of the United States, I. cordatotriloba and I. lacunosa. The resulting hybrid species, I. x leucantha, was first collected from Arizona as early as 1884 (C.G. Pringle) and 1912 (J.J. Thornber), and has shown up in four counties in Arizona over the past four decades - often as an agricultural pest or in disturbed areas. The logical thing to do would be to put I. x leucantha on the noxious weed list, but this was not the intellectual strategy pursued by the Arizona Department of Agriculture.
At any rate, all of our native Ipomoea species are currently listed on the noxious weed list, while two of them are simultaneously in the Arizona Rare Plant Field Guide. It is shocking to think of any native plant species being declared a noxious weed. In fact, not even our native desert broom (Baccharis sarathroides) has been placed on the noxious weed list. Another unfortunate aspect to this is that many land management agencies use the state noxious weed list as a guide for invasive plant management. At this time, we are not legally able to sell native Ipomoea vines. We hope that common sense will eventually prevail.