“rolled-leaf wet-ground moss”
How to recognize rolled-leaf wet-ground moss: Hyophila involuta is a small cushion moss with leaves that are tightly inrolled when dry, at which time they appear linear and are quite inconspicuous. When wet, the leaves are broadly expanded and often have serrulate tips and a long single costa. Upon dissection tiny brood bodies are often found in the leaf axils between the leaves and stem. The odd-shaped green brood bodies are connected to the leaf axil with a clear branched stalks. Under the microscope the leaf cells are flat on the back of the leaf and and very convex on the surface of the leaf. There are only a few moss genera that have the edges of the leaves inrolled; Weissia shares this behavior.
Where to find rolled-leaf wet-ground moss: Hyophila involuta occurs on wet rocks in and along brooks, generally in calcareous spots.