Hi,
I am a forester in central Louisiana, and by no means a gardener. However, I have always been fascinated by orchids. I am very interested in obtaining the skills to identify native orchids that may be present on the lands I manage. There is a book, now long out of publication, by John Lynch Orchid Collecting in Louisiana. If anyone one knows of an available copy, I would greatly appreciate the lead.
Here is a book that might be of interest to you, National Audubon Society Field Guide to North American Wildflowers. While not as specific as the one you are looking for it is better than nothing.
Greetings from your neighbor to the west. I highly recommend Wild Orchid of Texas by Joe and Anne Liggio. Most orchids found in TX are also in LA, with some exceptions of course.