Common Horsetail, Field Horsetail, Scouring Rush: Equisetum arvense (Synonyms: Equisetum arvense var. alpestre, Equisetum arvense var. boreale, Equisetum arvense var. campestre, Equisetum arvense var. riparium, Equisteum calderi)
River Horsetail, Swamp Horsetail, Water Horsetail: Equisetum fluviatile (Synonyms: Equisetum fluviatile var. limosum, Equisetum limosum)
Dwarf Horsetail, Dwarf Scouringrush, Dwarf Scouring Rush: Equisetum scirpoides
Wood Horsetail, Woodland Horsetail: Equisetum sylvaticum (Synonyms: Equisetum sylvaticum var. multiramosum, Equisetum sylvaticum var. pauciramosum)
Alaskan Scouringrush, Small Horsetail: Equisetum variegatum ssp. alaskanum (Synonym: Equisetum variegatum var. alaskanum) ?
Variegated Scouring Rush: Equisetum variegatum ssp. variegatum (Synonyms: Equisetum variegatum var. anceps, Equisetum variegatum var. variegatum, Hippochaete variegata)