Willow moss (Fontinalis antipyretica ) is a fully aquatic native moss , living mostly in fast flowing rivers and streams and some still waters were it attaches to rock and wood ,it can reach lengths of up to 60cm ,Reproduction is mostly by stolons or by the rooting of detached fragments ,this is a Coldwater species but can also live in tropical conditions ,being a native species it can easily survive outdoors year round and doesn't die back in winter.