Scouring Rush, Rough Horsetail and Winter Scouring Rush.
Description:
Equisetum hyemale is a non-flowering, rhizomatous evergreen perennial. It has rush-like aerial unbranached stems that persist more than one year. The stems range from 18 to 220 cm in height. Modified leaf Sheaths separate the stems; they are dark at the base and brown to grey above. Fruiting cones have a pointed apex and green spherical spores. The cones mature in summer. Often old stems develop branches with cones in the spring.
The common name scouring rush was earned because the plant was used to scrub and polish dishes, silverware and to sand wood. It was also used as homeopathic treatments for several illnesses from cystitis to urethritis. The method was to take the fruiting cones boil or fry and eat. Ingestion of Equisetum hyemale is no longer recommended because it disrupts the thiamine metabolic cycle and is toxic.
Equisetum is a very invasive plant with branched creeping rhizomes. After establishment it is extremely difficult to remove. If a small piece of rhizome is left in soil it will sprout a new plant. If using in gardens use barriers to restrict growth zone or plant in pots.
Climate:
They thrive in riparian zones and bog gardens, but can tolerate several soil varieties. A Bog garden is an area of saturated soil that is never allowed to dry out. Equisetum hyemale prefers wet feet and dry ankles.
Geographic distribution:
Equisetum hyemale is native to the United States and Eurasia. It grows in Alaska including the Aleutian Islands, all other North American states, Mexico and Central America in Guatemala. It grows as an invasive pest in New Zealand and Australia.
Links:
Pest in New Zealand
Photos
Equisetum grove
Structure
Reference:
Equisetum hyemale subsp. affine (Engelmann) Calder & Roy L. Taylor, Canad. J. Bot. 43: 1387. 1965.
Equisetum robustum A.Braun var. affine Engelmann, Amer. J. Sci. Arts 46: 88. 1844;
Flora of N. America http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=111897