Equisetum palustre L.
Equisetum palustre L. var. americanum Vict.
Equisetum palustre L. var. simplicissimum A. Braun
Equisetum palustre L. var. americanum Victorin
Marsh horsetails are smaller and more delicate looking than most other horsetails. They favor shallow wet areas with sandy soils, such as marshes and swamps. They are rare relative to other members of this genus. Once established, though, they can be practically impossible to eliminate, and are often considered invasive.
Plants: Plants are evergreen, and 4-20" (10-50 cm) tall. Stems have a rough texture, 4-12 (usually 8-10) ribs, and are ¹/₃₂-⅛" (1-3 mm) around. In cross section, stems show vallecular canals about the same size as a central hollow region. The central hollow is much less than half the diameter of the stem. Fertile and sterile stems look pretty much identical, except for the presence of a spore-bearing conelike structure at the tip of the fertile stems, vs. a stem that tapers to a point in sterile stems. The first sheath on the branch has 5 or 6 narrow teeth, and the first branch internode is shorter than the stem sheath. Fertile and sterile stems also emerge at about the same time.
See Equisetum for comparison charts.
Leaves: Sheaths appearing at nodes along the stem contain 8-10 tiny, non-photosynthetic leaves, shaped like sharp dark spears.
Fruits: A conelike structure, the strobilus, about ¾-1" (2-3 cm) long appears at the tip of each fertile stem. The strobilus contains numerous tiny spores 35-45 µm in size.
Edibility: Not edible, but not toxic to humans except in large quantities. However, it is toxic to horses, due to palustrin; and piperidine causes lameness in cattle.
Equisetum palustre on warbletoncouncil.org
Equisetum palustre on www.delta-intkey.com
Equisetum palustre on CalPhotos
Equisetum palustre at the Lady Bird Johnson Wildflower Center
Equisetum palustre at the Central Yukon Species Inventory Project
Equisetum palustre on Wikipedia
Equisetum palustre at the University of Wisconsin-Green Bay Cofrin Center for Biodiversity
Equisetum palustre on Plants for a Future, a resource and information centre for edible and otherwise useful plants
Equisetum palustre on eFloras
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. 348.
Equisetum palustre description by Thomas H. Kent, last updated 1 Dec 2020.