[Horsetails East of the Cascade Mountains of Oregon and Washington]
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

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)

Young common horsetails growing in roadside gravels in Summit Prairie, Malheur National Forest................August 2, 2011.
Paul Slichter