An order of the division Spenophyta, subkingdom Embryobionta. The Equisetales, commonly known as horsetails, is represented by a single living genus, Equisetum, with about 25 species found both in moist and dry habitats. These plants grow throughout the world, except in Australia and New Zealand. The plants range from herbaceous to shrubby and rarely exceed 3 or 4 ft (0.9 or 1.2 ft) in height, although some tropical species grow much taller.