Ptychostomum cyclophyllum (Schwaegr.) Bruch & Schimp. in B.S.G.
Egg-leaf True Moss
Mnium cyclophyllum, Bryum cyclophyllum
Basis for Listing
Bryum cyclophyllum (egg-leaf true moss) has a nearly continuous northern hemisphere distribution of boreal affinity. It occurs as a colonist on wet soils that are subject to inundation. The species has been recorded regionally from Ontario and Wisconsin. In Minnesota, a single population has been found on Susie Island in Cook County (North Shore Highlands Subsection). With only one recorded population, there is too little information available at this time to detect a statewide population trend. Further inventory work is needed to clarify the species’ abundance and distribution in the state (Janssens 2005). Based on the species’ apparent rarity, Bryum cyclophyllum was designated of special concern in 2013.
Bryum cyclophyllum can grow in dense to open turfs, appearing green or yellow-green in color. Stems are typically 0.5-3.0 cm (0.2-1.2 in.) long and can be simple or forked. Leaves are not crowded along the stem and are approximately 2.0 mm (0.08 in.) long, oblong-ovate to elliptic, with a rounded apex. Margins are entire, with the costa (midrib) ending somewhat below the apex. When leaves are dry, they can be strongly contorted to shrunken. Setae are red brown, 2.0-4.0 cm (0.8-1.6 in.) long, with yellow-brown pendulous capsules that are elongate, 2.0-4.0 mm (0.08-0.16 in.).
Across its range, P. cyclophyllum occurs in wet and sandy or organic soil along streams and wetlands or among roots of trees subject to inundation. In Minnesota, it has only been recorded from a single location, a black spruce swamp.
Biology / Life History
This species is dioicous (male and female reproductive organs on separate plants). Further specific details for this species are not documented; however, the protonema, spore germination, and development are typical of most mosses.
Conservation / Management
The occurrence of P. cyclophyllum has likely declined in the United States due to the fact that this species’ habitat occurs in wetlands and along streams in low to mid-elevation regions, where human development is often concentrated (Spence 2007). Changes in hydrology within this species’ habitat could be a threat, whether due to climate change or human disturbance, such as draining or road building and maintenance adjacent to or within wetlands.
Best Time to Search
The best time to search for P. cyclophyllum is from May through September or essentially anytime the ground is not covered by snow.
Conservation Efforts in Minnesota
The lone site for B. cyclophyllum in Minnesota is on Susie Island in Lake Superior, which is now owned by the Grand Portage Band of Lake Superior Chippewa. Under band control, "human influence on the island will be kept to a minimum in order to protect areas of cultural significance as well as the natural environment".
Erika R. Rowe (MNDNR), 2018
(Note: all content ©MNDNR)