Equisetum giganteum (Giant Horsetail)

Native to tropical and subtropical America, this perennial herb spreads through underground rhizomes and grows in wet ground, including river margins. Its green, hollow stems are divided by distinct joints and carry regular whorls of slender side branches. Small leaves are joined into toothed sheaths around the nodes. Tall plants often support one another by interlacing their branches in dense stands. The plant reproduces by spores rather than flowers or seeds, with spore-producing cones developing at the ends of stems or branches. Photographed in Colombia.