Splachnum rubrum Hedw.
Red Parasol Moss
Basis for Listing
Splachnum rubrum (red parasol moss) is an exceedingly rare and disjunct species in the boreal bioclimatic zone, including northern Europe, North America, and Asia. Regionally it has been found in Ontario and on Isle Royale, Michigan (Marino 2009). Five populations of S. rubrum have been recorded so far in Cook County (Border Lakes Subsection): two in 1984, one in 2004, and two in 2010. This species grows exclusively on old Moose (Alces americanus) dung and thus only occurs throughout the range of Moose. The substantial decline of Minnesota’s Moose population over the past few decades is cause for concern, not only for the Moose but also for S. rubrum. Additionally, the short life-history of red parasol moss makes any population quite vulnerable to local extinction. On the basis of its extreme rarity, limited state and regional distribution, highly specialized microhabitat and life-history, Splachnum rubrum was listed as an endangered species in 2013.
In the field it is impossible to differentiate plants without sporophytes from other species within the family Splachnaceae or even within the order Splachnales. However, when sporophytes develop, and when they are reaching maturity on their tall setae (5-13 cm [2-5 in.]; Marino 2009), there is no possibility of mistaking this species. The very large (6-11 mm [0.24-0.43 in.] across) convex umbrella-shaped apophyses (a widely expanded part of the capsule, just below the urn) are smooth and bright magenta-red. They give the appearance of an angiosperm flower. A similar species, commonly found with S. rubrum, is its congener S. luteum (yellow moosedung moss), which has not yet been observed in Minnesota (Janssens 2010) but is listed for Ontario (Marino 2009). Splachnum luteum has discoid-umbrelliform and greenish yellow to orange-red apophyses. The most common Splachnum species in the state is S. ampullaceum (small capsule dung moss), presently with > 10 records. This species is also found on Moose dung, though it is less particular as other herbivore dung will do. Its apophyses, when mature, are rugose, top-shaped, with a yellow to pinkish or pale purple color. Other related species in the family recorded for Minnesota are Tetraplodon angustatus (toothedleaf nitrogen moss; < 10 records; apophysis green, becoming brown; longer and wider than the urn; the leaves of the gametophytes have large sharp teeth not present on the leaves of the Splachnum species) and T. mnioides (entireleaf nitrogen moss; one confirmed record in Koochiching County). These two species germinate more specifically on carnivore dung or old bones and owl pellets (Marino 2009).
Splachnum rubrum grows exclusively on old Moose dung and thus only occurs in habitats occupied by Moose. It occurs in Minnesota in northern poor conifer swamp, northern rich spruce swamp, and northern poor fen.
Biology / Life History
Splachnum rubrum is a strictly coprophilous (growing on dung) and entomophilous species (spores distributed by insects the plants attract by producing species-specific odors; Marino 1997; 2009). The green plants (gametophores) are usually rapidly overtopped by the surrounding Sphagnum plants. When the plants are producing sporophytes, and these have matured, little is usually still recognizable of the original Moose droppings on which they germinated and on which their spores had been deposited by flies (Diptera).
Conservation / Management
The substantial decline of Minnesota’s northwestern Moose population over the past two decades and the predicted decline of its northeastern population are cause for concern (MN DNR 2011). A clone of Splachnum rubrum with mature sporophytes is also extremely obvious and runs a definite risk of being extirpated by any uninformed collector or even a curious passerby.
Best Time to Search
The best time to search for S. rubrum is when sporophytes are present in late summer or early fall.
Conservation Efforts in Minnesota
As the species is so distinctive and also extremely vulnerable, new records should preferably be cataloged by a photograph rather than a formal collected herbarium voucher (C. E. Anderson 2004 pers. com.; Janssens 2010). Specific efforts for conservation are difficult as the species has a short-shuttle life strategy (completes its entire life cycle, or at least the visible sporophyte generation, in little more than one year). Additional sightings will only be possible in a haphazard fashion. An educational effort, making people aware of the species’ existence and status, might help in limiting any further destruction of populations.
Since S. rubrum grows exclusively on old Moose dung, the species’ survival in Minnesota is intrinsically tied to the Minnesota Moose population The Minnesota Moose Research and Management Plan (MNDNR 2011) outlines six objectives (hunting, research, deer management, habitat, social considerations, and communication) the Minnesota Department of Natural Resources is working on to help the Moose population, which if successful will support the survival of S. rubrum.