Caulkins & R.E.Wyatt (Small) 1991 - Caulkins DB, Wyatt R (1990) Variation and Taxonomy of Phytolacca americana and P. rigida in the Southeastern United States. Bulletin of The Torrey Botanical Club 117: 357-367. doi: 10.2307/2996833.
There is no corrections for Phytolacca americana var. rigida yet.