We have information from several sources:
The American Mayapple and its Potential for Podophyllotoxin Production Rita M. Moraes, Hemant Lata, Ebru Bedir, Muhammad Maqbool, and Kent Cushman
Propagule Type and Planting Time for Field-established MayappleMuhammad Maqbool, Kent E. Cushman, and Rita M. Moraes
Assessment of Genetic Diversity in Podophyllum peltatum by Molecular MarkersHemant Lata, Rita M. Moraes, Andrew Douglas, and Brian E. Scheffler
Bioprospecting for PodophyllotoxinEbru Bedir, Ikhlas Khan, Rita M. Moraes
Sievers, A.F. 1930. The Herb Hunters Guide. Misc. Publ. No. 77. USDA, Washington DC.