The Great Marsh Institute

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Elverson, PA
The Great Marsh Institute

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Supporting scientific studies, educational opportunities, and protecting the unique Great Marsh in no

10/30/2026

Once again it's time for the baseline flow testing for . Road salt is a major, under-appreciated pollutant, and our big source is the PA Turnpike, which has likely contributed to our 20 acres of phragmites. Our seven samples this year showed that even at baseline (dry weather, eight months+ since last salting) the water in streams near the turnpike embankment is saltier than basically everywhere else. And thanks for volunteer Bradley Wrage for helping out again this year.

10/23/2026

Did a little experiment (or two) with Carex stricta, tussock sedge as we work on how we'll restore (plant/seed with native species) some areas we're currently treating for and . In late spring we collected a whole lot of sedge seeds (really tiny seeds). We put some in a fridge with some damp vermiculite for a few months (cold striation). It turns out the seeds do need that cold storage to sprout.

10/05/2026

A game cam + some peanut butter

Southern flying squirrels, a gray squirrel, and a white-footed mouse

09/30/2026

Broadleaf arrowhead (Sagittaria latifolia) is the most-observed species at the Great Marsh, per iNaturalist. That's probably because it was flowing when the Philadelphia Botanical Club visited, but it is nonetheless a very common plant in the marsh, with flowers emerging at the end of the summer. It apparently has edible tubers, which were important to indigenous peoples. And if you're wondering about an astrological link for the genus name, you're on the right track. The constellation Sagittarius means "archer" in Latin (apparently looks like a centaur archer), and the leaves of the plant look like arrowheads.

09/25/2026

Great news! We have set up an iNaturalist project covering all the territory where GMI operates. Or totals so far ain't too shabby, with 1,500+ observations of 582 species. Come on out with your nature group or join one of our events and help us add to the documented biodiversity of the Great Marsh https://www.inaturalist.org/projects/great-marsh-wildlife

09/23/2026

We had a great time at the Creatures of the Night event. Bats were out (but not easy to photograph) and we got to check out bat food: all the nocturnal flying critters, like this large caddisfly. Please keep an eye on our events page for the next walk, and if you'd like to bring your nature group to the marsh, be in touch.

09/18/2026

Here's a ground-level view of one of the beaver dams in GMI's new parcel. It's a little hard to make out, but above the dam is still water with a few shrub hummocks and submerged trees, while below the dam is a narrower channel overgrown with bur reed and smartweeds, flanked by dense thickets of dogwood and other shrubs. We look forward to finding ways to bring the public into this amazing habitat, and connecting it with researchers.

09/08/2026

Join us Sunday evening for our Creatures of the Night (Bats+ whoever else is flying around) walk. For more details and to sign up: https://greatmarshinstitute.org/event/creatures-of-the-night/

09/02/2026

GMI is proud to introduce our new addition, 80 acres acquired in partnership with French and Pickering Creeks Conservation Trust. We hope it will open more opportunities for people to visit and connect with the Great Marsh. It's got upland woods, bottomland woods, and wetlands flanking Marsh Creek. Towards the end of the video you'll see the work of beavers, including an old low-head dam that the enterprising rodents have appropriated. The drone footage is from the winter. Maintenance and programming at the parcel will be supported by an endowment stewarded by the Chester County Community Foundation.

08/14/2026

Purple loosestrife can be a major pest in marshes, but over the past few years GMI has released purple loosestrife beetles, which help keep it in check. There's probably no getting rid of the , but the keep it from being truly . Swipe over to see the holes in the leaves made by the wee beetles. The beetles are a great success story for North America, and a hit here at the Great Marsh too.

Address

34 Moores Road
Elverson, PA
19520

Website

http://www.greatmarshinstitute.org/

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