Equisetum fluviatile L.
Equisetum fluviatile L. var. limosum (L.) Gilbert
Equisetum limosum L.
Water Horsetail, Swamp Horsetail
Water horsetail is the smoothest of the horsetails. Fluviatile is Latin for “pertaining to rivers,” and this horsetail is common in wet, marshy areas. Like other horsetails, water horsetails have a remarkably high silica content, making them abrasive enough for scouring or sanding.
Identification: Water horsetails occur in dense colonies, where they may be unbranched or multiply branched. If branches are present, they are less than 3" (7.6 cm) long. Each segment boundary is ringed by a series of tiny, black-tipped scale leaves. The stems of water horsetails are smoother than those of marsh horsetails. See Equisetum for a comparison chart.
Cobb, Boughton, Farnsworth, Elizabeth & Lowe, Cheryl, Peterson Field Guides: A Field Guide to Ferns and Their Related Families of Northwestern and Central North America, Houghton Mifflin Company, 2005, p. 342
Equisetum fluviatile at the Lady Bird Johnson Wildflower Center
Equisetum fluviatile at the Washington State Department of Ecology
Equisetum fluviatile on Wikipedia
Equisetum fluviatile on Plants for a Future, a resource and information centre for edible and otherwise useful plants
Equisetum fluviatile at the University of Wisconsin's Robert W. Freckmann Herbarium
Equisetum fluviatile on eFloras
Equisetum fluviatile description by Thomas H. Kent, last updated 2 Jan 2019.