FloraOfNewZealand-Ferns-6-BrownseyPerrie-2015-E ...

The family Equisetaceae is represented in New Zealand by one genus with two naturalised and one casual species; all are classified as Unwanted Organisms. Equisetum arvense was first recorded in Wanganui in 1922 and has since spread aggressively along river banks throughout much of the southern North Island, and northern South Island. Equisetum hyemale is less invasive, occurring in mostly urban areas from Whangarei to Invercargill, whilst E. fluviatile is known from just one collection near Huntly. All species of Equisetum have a characteristic growth form with erect aerial stems that are usually hollow, jointed and longitudinally grooved, produce whorls of branches and leaves, and bear conspicuous terminal strobili which themselves comprise whorls of peltate sporangiophores. Species of Equisetum are commonly known as horsetails because of their distinctive appearance, or as scouring rushes because of their high silica content.