Equisetaceae (Horsetail Family)
General - Green, bottlebrush-like perennial, from spreading rhizomes; stems annual, erect, hollow, slender, 10 - 50 cm tall, 1 - 4 mm thick, die back each year; fertile and sterile stems dissimilar; fertile stems unbranched at first, later develop many whorls of branches; sterile stems mostly single, whitish green, with 10 - 18 minutely roughened ridges, many whorled branches, fine, 3 - sided; first branch segment not longer than adjacent stem sheath.
Leaves - small scales fused into pale sheaths; sheaths 2 - 6 mm long, with 8 - 10 brown, white- edged teeth.
Spore Clusters - in 1 - 2 cm long cone, on long talk at tip of bottlebrush-like shoot (whorled branches may be absent at first), soon fall off.
Moist woods, thickets and meadows; widespread across Northwestern Ontario; circumpolar.
Meadow horsetail is often confused with common horsetail; however, all of meadow horsetail's shoots are green and have whorls of branches. Only common horsetail has small, brown, unbranched, fertile stems. The sterile stems of meadow horsetail are generally more slender and fragile looking than those of the lengthy of the first branch segment relative to the length of the adjacent stem sheath. The branch segment is shorter than or equal to the stem sheath in meadow horsetail, but longer in common horsetail. Horsetails contain an enzyme (thiaminase) that destroys vitamin B1 (thiamine). In large quantities, they have caused deaths in livestock, though poisoning is quickly reversed by removing horsetails from the diet. Their effect on humans is not completely understood, but raw horsetails can act as a poison. Cooking destroys the thiaminase. Only very small quantities should be taken internally, and people with high blood pressure or other cardiovascular problems are warned against using horsetail.
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