The roughly centimetre-long capsule of the green shield-moss is a real giant in the world of mosses. By contrast, the leaves at the bottom of the capsule stalk are tiny.
The protected green shield-moss grows on heavily decayed fallen wood in old moist coniferous forests. Its spores dispersed by wind in early summer need moisture – more than 48 hours of drying will destroy them. Colonization of new localities is also hindered by a menagerie of snails, mice and birds eating its young capsules.
The green shield-moss is found mostly on the islands of West Estonia and in North Estonia. It is threatened by the loss and fragmentation of its habitats and, more recently, also by summer dry periods.
Estonia is also home to another shield-moss – the brown shield-moss. However, as it grows on the ground in dry and well-lighted dune pinewood and inland dune habitats, the relatives are unlikely to be mixed up.