Ask Mr. Smarty Plants

The question of nativity is one that is often posed to Mr. Smarty Plants.  We receive questions about specific plants and also the more general question of how "native" is defined.  For the second question, our definition is a plant is native to an area that evolved or arrived in that area without the assistance of man. 

This issue is very important to us since, by institutional policy, our research is limited to those plant species native to North America north of Mexico.  Plant species that are native to Mexico but nowhere in the United States are not included in our research and thus, not in the Native Plant Database

The Caesalpinia species are certainly beautiful plants and some do very well in the Austin area.  Caesalpinia pulcherrima is native to the West Indies and tropical America.  Caesalpinia gilliesii is native to South America.  Caesalpinia mexicana is native to Mexico and according to a some references also occurs naturally in the Lower Rio Grande Valley of Texas.  If that were the case, Caesalpinia mexicana would qualify for inclusion in our database.

Caesalpinia mexicana is common in the Lower Rio Grande Valley in landscapes.  However, after consulting with botanists who are intimately familiar with the native flora of south Texas, we believe that C. mexicana is not a natural constituent of that flora.  If we find compelling evidence to the contrary sometime in the future, we will happily add that species to our lists of native species.