Equisetum myriochaetum

Equisetum myriochaetum, also known as Mexican giant horsetail, is a species of horsetail that is native to Nicaragua, Costa Rica, Colombia, Venezuela, Ecuador, Peru and Mexico. It is the largest horsetail species, commonly reaching 4.6 metres (15 ft), with the largest recorded specimen having a height of 7.3 metres (24 ft). At each node is a whorl of as many as 32 branchlets. It is semi-aquatic and is often found growing on riverbanks.

The species is harvested for medicinal use. In Mexico, the species is harvested and sold to treat kidney disease and type 2 diabetes. It has traditionally been used as a diuretic.