Gathering Moss: A Natural and Cultural History of Mosses

Portrait of Splachnum

Portrait of Splachnum  121 Portrait of Splachnum  T he jet stream flows through the stratosphere like a muddy river. It cuts from one shore and deposits on the other, homogenizing its load of sediment. Swept along in the current are airborne seeds and spores, keeping company with vagrant spiders. Every continent is awash in the same aerial plankton. The wonder is not that the earth should be so richly populated, but that it is not everywhere the same. Somehow, each wandering spore finds its way home. This global cloud of spores powders every surface with the possibility of mosses. I saw the same species in my driveway in upstate New York that I encountered the next morning in the sidewalk cracks of Caracas. This same species chinks cracks in the cinder blocks of Antarctic outposts. It is not the proximity to the equator that matters, but the singular chemistry of pavement which makes a home. The boundaries that define where a particular species of moss calls home are often more narrow. Some are strictly aquatic, some are terrestrial. Epiphytic mosses restrict themselves to the branches of trees, but some epiphytes settle only on sugar maples and others only in the rotten knotholes of sugar maples growing on limestone. There are generalists that are ubiquitous on any patch of open soil, and specialists which favor the dirt tossed up by the diggings of pocket gophers in the tall-grass prairie. Some saxicolous (rock-dwelling) mosses can live on granite, others only on limestone and Mielichoferia only on rocks containing copper. But no moss is more fastidious in its choice of habitats than Splachnum. Absent from the usual mossy haunts, Splachnum is found only in bogs. Not among the commoners like Sphagnum that build the peaty hummocks, not along the margin of the blackwater pools. Splachnum ampullulaceum occurs in one, and only one, place in the bog. On deer droppings. On 122  Gathering Moss white-tailed deer droppings. On white-tailed deer droppings which have lain on the peat for four weeks. In July. I’ve never found Splachnum by looking for it. Days before my moss class was scheduled to begin, I would go to a quaking bog in the heart of the Adirondacks in hopes of finding a patch to show my students. I’d found it there before, but only when I was looking for something else. Squishing through the muck my footsteps would release the faintly sulfurous gases. I searched over the carpet of peat, finding pockets of rare pitcher plants, sundews, and spider webs stretched over the branches of bog laurel. I found plenty of deer droppings, and coyote scat too, but the tidy piles of brown pellets are empty. While all are very rare, any bog could have as many as three different species of Splachnum residing there. Splachnum ampullulaceuminhabits the droppings of whitetailed deer. Had a wolf or coyote followed the scent of the deer into the bog, its droppings would have been colonized by another species, S. luteum. The chemistry of carnivore dung is sufficiently distinct from that of herbivores to support a different species. If a moose strode through the bog, and made a contribution to the local nitrogen economy, its droppings would be of little use to either of the other Splachnum species. The moose droppings have their own loyal follower. The family to which Splachnum belongs includes several other mosses with an affinity for animal nitrogen. Tetraplodon and Tayloria can be found on humus, but primarily inhabit animal remains such as bones and owl pellets. I once found an elk skull lying beneath a stand of pines, with the jawbone tufted with Tetraplodon. The set of circumstances that converge to bring Splachnum into the world is highly improbable. Ripening cranberries draw the doe to the bog. She stands and grazes with ears alert, flirting with the risk of coyotes. Minutes after she has paused, the droppings continue to steam. Her hoof prints leave indentations in the peat, which fill with water and leave a trail of tiny ponds behind her. The droppings send out an invitation written in wafting molecules of ammonia and butyric acid. Beetles and bees are oblivious to this signal, and go on about their leaf of Splachnum Portrait of Splachnum  123 Splachnum work. But all over the bog, flies give up their meandering flights and antennae quiver in recognition. Flies cluster on the fresh droppings...