POI M19

Once They Were Giants

The odd green spikes growing here are Common Horsetails, fern relatives that spread by rhizomes and reproduce by spores. Their jointed stems feel abrasive because they contain silica, a feature that gave rise to the name “scouring rush.”  Common Horsetails produce two types of stems: Green sterile ones that photosynthesize in summer, and brown scaly fertile ones sporting a spore cone. The latter appear in spring and wither before the sterile stems appear.  During the age of dinosaurs, Horsetails grew as tall as trees but eventually lost their stature when flowering plants including trees evolved.