Primary stems prostrate and rooting, 30-100cm long, usually freely branching. Lateral sterile stems also prostrate, but fertile ones erect, 5-10cm long. Leaves 3-5mm, linear, more or less appressed or incurved, bright green, the slender tip bearing a long white hair. Sporangial spikes 2-5cm long, solitary or in pairs, on long, leafless stalks. Circumarctic and north temperate zone, also on mountains to and across the tropics to the southern temperate zone (see under L. fastigiatum).