Coming this month to a bog near you...
Splachnum has to be one of the most interesting genera of mosses in the world. When we think about habitat specificity, we usually think of some sort of endangered or rare habitat type. The mind definitely would not go to poop. Yet, this is exactly where Splachnum grow.
These mosses are specialists on animal dung. What's more, since different animals produce different kinds of poop with different chemical makeups and different textures, different species of Splachnum specialize on different kinds of poop. Deer poop is a favorite haunt of Splachnum ampullulceum whereas coyote or wolf poop will be inhabited by Splachnum luteum.
If this ecology wasn't specific enough, Splachnum cannot inhabit poop anywhere it lands. These mosses can only be found on poop which has landed in either a bog or a fen. As one can probably guess, poop quickly breaks down. Its ephemeral nature, especially in a wet bog, means that Splachnum mosses can't be bothered with a chance encounter via wind-borne spores. Instead, these mosses utilize other poop specialists, flies.
Splachnum spores are produced at the tip of very long, very ornate sporophytes. They are large, colorful, and some even produce a fetid odor in hopes of attracting their winged spore dispersers. Once a fly lands to investigate, it becomes covered in sticky Splachnum spores. When it lands on another pile of poop, some of the spores will fall off and find a new pile of rotting dung to colonize. Because poop decomposes rather quickly, the Splachnum mosses don't bother with lots of vegetative growth. A small gametophyte quickly produces a grandiose display of sporophytes so that the next generation can get a head start before the fecal substrate decomposes out from underneath the parent. Also, Splachnum colonies actively skew their sex ratio to favore females over males 2:1. This ensures that there is as much spore production as possible.
July is the perfect time of summer in the North to go looking for Splachnum. Keep an eye out and tread lightly. These lovely little mosses with their peculiar natural history are a real gem to discover. They are a wonderful reminder of how complex of a world we live in.
Photo Credits: caspar s (http://bit.ly/1H7P4pf), madcowcult (Wikimedia Commons), and Biopix: A Neumann (http://bit.ly/1HFoUh0)