Ferns 2026

Slender Rockbrake

Slender or Fragile Rockbrake (Cryptogramma stelleri) is supposed to be in Franklin and Berkshire Counties in MA, but we have not found any yet, so we travel to Vermont to a special site. It is generally described as uncommon, and GoBotany lists it as extremely rare in most of New England and uncommon in Vermont. It is special and always worth the trip! Slender Rockbrake is a small delicate fern that grows in cool, moist, shady limestone or calcareous rock faces and ledges. It dries up early in the summer.

The sterile and fertile fronds are pale green and different in form. Both are shown in the photo. The larger longer slimmer fronds in front of my hand are the fertile fronds. The sori are covered on the underside edge of the frond by inrolled margins, The sterile fronds are smaller with rounded pinnae. One is shown above the fertile frond on the right side of the photo.

The name comes from the Greek kryptos (hidden) and gramme (line, for the line of sori hidden under the inrolled margins of the fertile fronds) (Chadde, 2023). If you ever happen to see these in Massachusetts, we would love to know (& Natural Heritage & Endangered Species Program as well)!

We are planning a Fern Hike for this coming Sunday, June 14th (Flag Day) at High Ledges in Shelburne MA. See the calendar listing for details. We will do a loop of a couple of the trails. The trails are generally narrow and uneven, so wear good footwear and be prepared for possible insects or poison ivy. It is an interesting place, with a number of ferns and clubmosses to see, including Broad and Narrow Beech, Maidenhair, and Northern Oak Ferns.

Posted: to PV Fern News on Tue, Jun 9, 2026
Updated: Wed, Jun 10, 2026