Ask Mr. Smarty Plants

You are correct, our ultimate source for determining nativity is the USDA, and this USDA Plant Profile Map shows Blue Porterweed (Stachytarpheta jamaicensis) as native to the lower 48 states, Puerto Rico and the Virgin Islands but introduced in Hawaii. This can be attributed to many things, but mostly to the fact that our Native Plant Database is alway a work in progress. We are much more embarrassed when we learn that we have listed a non-native as native than we are when it is the other way around, but still, we appreciate your bringing it to our attention.

The USDA source listed above shows it native to Alabama and Florida, so we are a little curious as to why it was being sold as a native plant in a nursery near Houston. Our whole point in advocating native plants is that there are many multiples of different growing conditions in North America - soils, temperatures, rainfall, even the length of daylight. When we answer a question about a specific plant, we always first check to see where that plant evolved and grows naturally, in order to warn our visitor if we don't think it can survive where they are gardening. 

To that end, we will do a little research on the Internet and you can read some of the information we find to determine if you can expect it to do well in Harris Co., TX.

A lot of user comments from the forum Dave's Garden on this plant. Natives for your neighborhood, a conservation website for south Florida. The Leon Levy Native Plant Database -  oops, that's from the Bahamas. "Native" is in the eye of the beholder.