Latin equus - horse, seta - bristle; in reference to the horse-tail like branchlets.
Terrestrial or aquatic plants. Stems long-creeping below ground, above ground they are hollow and grooved, divided into distinct units by joints (nodes). Branches arranged in whorls. Leaves many, reduced and tooth-like in regular whorls at the nodes and united into a sheath at the base. Sporangia in stalked organs (sporangiophores) that are clustered into a terminal cone-like structure.
c. 15 species of almost world-wide distribution but mostly temperate Northern Hemisphere; notably absent from Australia and New Zealand.
Hauke (1963, 1978).
Source: (1995). Equisetaceae. In: . Horticultural Flora of South-eastern Australia. Volume 1, Ferns, conifers & their allies. The identification of garden and cultivated plants. University of New South Wales Press.