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Name derivation:


Other common names: Scouring rush, horse pipes, joint-grass, bottle-brush


Class Sphenopsida or Equisetopsida;  Order Equisetales; Family Equisetaceae; Genus Equisetum L.; 15 extant (living) species are currently accepted taxonomically.

Together the four classes of Sphenopsids (Equisetum), Lycopsids (Lycopodium and Selaginella), Psilopsids (Psilotum) and Pteropsids (ferns) are the pteridophytes.


Plants 13 cm (E. scripoides) to >8 m (E. giganteum and E. myriochaetum) tall.  The stem diameter of the tallest plants is up to 4 cm.  Stems are green and photosynthetic, with usually from 6 to 40 ridges.  Each ridge bears a non-photosynthetic short clasping leaf at nodes.  Green photosynthetic branches on each ridge are present on some species, absent in others.

Mainly homosporous (one spore type) sporophytes (dominant phase) bear spores on a terminal strobilus (cone).  In some species that have separate green sterile shoots, the spore-bearing shoots are non-photosynthetic (e.g. E. arvense), in others both shoot types are photosynthetic (E. palustre).

A heterosporous species (E. arvense) produces male prothalli.

Helpful colorful sketches of horsetail morphology are online.


Similar genera: