Common Horsetail, Field Horsetail: Equisetum arvense (Synonyms: Equisetum arvense var. alpestre, Equisetum arvense var. boreale, Equisetum arvense var. campestre, Equisetum arvense var. riparium, Equisetum calderi) -

Ferriss' Horsetail, Ferriss' Scouring Rush: Equisetum xferrissii (Synonyms: Equisetum hyemale x Equisetum laevigatum, Equisetum hyemale var. elatum, Equisetum hyemale var. intermedium, Equisetum intermedium) -

Swamp Horsetail, River Horsetail, Water Horsetail: Equisetum fluviatile (Synonyms: Equisetum fluviatile var. limosum, Equisetum limosum) -

Hybrid Horsetail: Equisetum xfont-queri (Synonym: Equisetum palustre x Equisetum telmateia) -

Common Scouring-rush, Common Scouring-rush, Scouring-rush Horsetail, Dutch Rush, Prairie Scouring-rush: Equisetum hyemale var. affine (Synonyms: Equisetum affine, Equisetum hyemale ssp. affine, Equisetum hyemale var. californicum, Equisetum hyemale var. pseudohyemale, Equisetum hyemale var. robustum, Equisetum praealtum, Equisetum robustum, Hippochaete hyemalis, Hippochaete hemalis ssp. affinis) -

Smooth Horsetail, Smooth Scouring Rush: Equisetum laevigatum (Synonyms: Equisetum funstonii, Equisetum kansanum, Equisetum laevigatum ssp. funstonii, Hippochaete laevigata) -

Nelson's Horsetail: Equisetum xnelsonii (Synonyms: Equisetum laevigatum x Equisetum variegatum, Equisetum variegatum var. nelsonii) -

Marsh Horsetail: Equisetum palustre (Synonyms: Equisetum palustre var. americanum, Equisetum palustre var. simplicissimum) -

Dwarf Scouringrush, Dwarf Scouring-rush, Sedgelike Horsetail: Equisetum scirpoides -

Wood Horsetail, Woodland Horsetail: Equisetum sylvaticum (Synonyms: Equisetum sylvaticum var. multiramosum, Equisetum sylvaticum var. pauciramosum) -

Giant Horsetail, Great Horsetail: Equisetum telmateia var. braunii (Synonyms: Equisetum braunii, Equisetum maximum, Equisetum telmateia ssp. braunii) -

Northern Scouring Rush, Variegated Horsetail, Variegated Scouringrush, Variegated Scouring Rush: Equisetum variegatum var. variegatum (Synonyms: Equisetum variegatum ssp. variegatum, Equisetum variegatum var. anceps, Hippochaete variegata) -