Tree Clump Moss

This brown moss is commonly found growing in medium-sized clumps On trees.
It is small, growing up to 1 inch (3 cm) tall. It forms in small clumps, and is slightly frail; it struggles more than most during dry spells.
When mature, emerald oblong capsules grow at the end of short, lime green sporophytes, eventually opening up during the early autumn to release dozens of spores.