Mayapple (Podophyllum Peltatum) Posted on May 18, 2021 by MC2 · Leave a comment Location : Herron Rookery & Great Marsh Trail – (Indiana Dunes National Park) Date : April 23 & April 25, 2021 – (Indiana Dunes National Park) Mayapple lining the trail at the Herron Rookery. The flower bud is just starting to poke out of this Mayapple at Cowles Bog in late April.