Original: They are perennial plants , either herbaceous and dying back in winter as most temperate species , or evergreen as most tropical species and the temperate species Rough Horsetail ( E. hyemale ) , Branched Horsetail ( E. ramosissimum ) , Dwarf Horsetail ( E. scirpoides ) and Variegated Horsetail ( E. variegatum ) .
Simplified: They are perennial plants , either herbaceous , they back in winter ( most temperate species ) or they are evergreen ( some tropical species , and the temperate species Equisetum hyemale , E. scirpoides , E. variegatum and E. ramosissimum ) .