“red penny moss”
How to recognize Rhizomnium punctatum: This moss, one of the genera that was split from Mnium, was placed in Rhizomnium with other species that do not have obvious teeth on the leaf border. When it is moist the 3-6 mm round to oval leaves are quite attractive; when dry they are contorted and twisted. It is usually found with the rhizoids only growing from the very bottom of the stem. Under the microscope sometimes a tiny tooth or apiculus can be send at the top end of the leaf, and by careful focusing up and down the multi-stratose layers of cells in the leaf border can be detected. Male plants are very obvious and can be easily inspected with a hand-lens; they are recognizable by a brownish cluster of tiny little antheridia (tiny cigar-shaped structures full of motile sperm when mature) in the center of a rosette of green leaves. It is an interesting exercise to tease one of these apart under a dissecting microscope, and then examine it closely under a compound microscope.
Where to find Rhizomnium punctatum: It is found on rocks, in and along streams and wet places, and also on soil and wood in these areas.