Emerald

This emerald moss is commonly found growing in medium-sized clumps On rotten logs.
It is short, growing up to 1 inch (3 cm) tall. It forms in small clumps and they overwhelm an area rapidly, and is extremely resistant; it is very difficult to kill.
When mature, emerald oval-shaped capsules grow at the end of short, lime green sporophytes, eventually opening up during the late autumn to release dozens of spores; it can cause severe allergic reactions.