Flesh-eating plants await on bog walk

As for insect-eating plants, Grady said, “Bogs tend to be very acidic and don’t have a lot of plant nutrients, so you often find quite a few carnivorous plants there.’’

This month’s guided walk to the Black Pond Bog Preserve is part of the watershed association’s series of “Hidden Gems’’ walks taking place Sundays near the North and South rivers — two principal South Shore waterways — and their tributaries. The series gives the public the opportunity to explore places to walk that may be unfamiliar and to learn about the sites’ rare features from local experts. In addition to carnivorous plants and a quaking bog, walkers will learn about Allegheny ant mounds, poisonous plants, and how to identify fireflies by their flash patterns.

The upcoming June 12 walk to Black Pond Bog will be led by wetland scientist Steve Ivas, who calls the site his favorite place in Norwell.

The preserve was the first property in Massachusetts acquired by the Nature Conservancy, a national land preservation organization, because of the bog’s unique glacial formation. It’s basically a kettle pond with a thick layer of peat on top, on which plants and even trees have grown. Ivas compares the bog to “an ice cube buried in the beach.’’ The ice preserves the shape of the hole while it melts, and over 10,000 years layers of sphagnum peat moss develop around its shoreline. Leather leaf plants catch hold in the moss and grow over the pond until the surface becomes a floating mat.

To experience the bog’s quake, Ivas has walkers jump in unison on one end of the boardwalk that crosses the bog and watch the cedar trees growing on its surface shake. “You can see the trees move,’’ he says. “The bog is so rare and such a good specimen.’’

The bog’s unique suite of carnivorous plants take their nitrogen from insects, including the pitcher plant in which bugs drown and are dissolved. However, while the plant’s “pitchers’’ are dissolving some insects, some kinds of mosquito larva have adapted to live in these micro-environments — and only there. “Nature abhors a vacuum,’’ Ivas said.