Proserpinaca

1. Flowers only in the axils of merely serrate leaves (i.e., plant heterophyllous); common.

P. palustris

1. Flowers in the axils of pectinate leaves (i.e., all leaves pectinate); very rare.

P. pectinata

All species found in Proserpinaca

Proserpinaca palustrisMERMAID-WEED 
Proserpinaca pectinataMERMAID-WEED 

Citation:

MICHIGAN FLORA ONLINE. A. A. Reznicek, E. G. Voss, & B. S. Walters. February 2011. University of Michigan. Web. December 16, 2017. http://www.michiganflora.net/genus.aspx?id=Proserpinaca.