One Princeton preserve I get to help take care of is the marsh at Rogers Refuge, which lies between the Institute Woods and the Stony Brook. The first photo shows fringed loosestrife, a native with shy flowers that, like mayapple, face downward. Most people associate the word "loosestrife" with purple loosestrife, an invasive exotic found in marshes and along streambanks, but the native loosestrife shows up in small patches here and there in Princeton preserves.
The second photo is of water hemlock, another native wildflower of wet areas.
More common is the native trumpet vine, growing on a tree not far from the observation tower that looks out over the marsh at the Refuge.
To get there, follow West Drive off of Alexander Road, stay left, and park in the lot just before you reach the water company buildings. The land is owned by the water company, but has a protective easement agreement with Princeton Township. Members of the Friends of Rogers Refuge (FORR) were responsible for helping preserve the marsh back in the 60s, and continue to provide impetus to manage its unique habitat.