Horsetail, Equisetum, is a primitive rush-like plant with jointed, hollow, leafless green stems bearing rings of fine branches, the sole survivor of a lineage that formed great forests in the age of coal, a genuine living fossil far older than the flowering plants. Its stems are stiffened with silica, so gritty that they were used for centuries to scour pots and to smooth wood and pewter, earning the names scouring rush and pewterwort. Its old domestic use to staunch bleeding and knit wounds is given here as folk history rather than medical claim.
Equisetum hyemale, the roughest and most heavily silicified of the horsetails, is still used today by professional makers of oboe and bassoon reeds, who finish the delicate cane with a strip of the dried stem under the trade name Dutch rush, a specialised survival of the plant's old scouring use in a craft where nothing synthetic has fully replaced it. Horsetail reproduces by spores rather than seeds, in the ancient manner of ferns and clubmosses, its fertile cone-tipped stems appearing separately from the green summer growth, a reproductive strategy that predates flowering plants by many tens of millions of years.
The plant's jointed, hollow stems can also be pulled apart and refitted together at each joint, a simple mechanical curiosity that has made horsetail a favourite hands-on specimen for teaching children about plant structure in nature study and forest-school settings today.