The horsetails are vascular plants, comprising 15 species of plants in the genus Equisetum. This genus is the only one in the family Equisetaceae, which in turn is the only family in the order Equisetales and the class Equisetopsida. This class is often placed as the sole member of the Division Equisetophyta (also called Arthrophyta in older works), though some recent molecular analyses place the genus within Pteridophyta, related to Marattiales. The molecular data, however, are somewhat ambiguous as of yet. Other classes and orders of Equisetophyta are known from the fossil record, where they were important members of the world flora during the Carboniferous period.

The name horsetail arose because it was thought that the stalk resembled a horse's tail; the name Equisetum is from the Latin equus, "horse", and seta, "bristle". Other names, rarely used, include candock (applied to branching species only), and scouring-rush (applied to the unbranched or sparsely branched species). The name scouring-rush refers to its rush-like appearance and because the stems are coated with abrasive silica that led them to be used for scouring cooking pots in the past.

The genus is near-cosmopolitan, being absent only from Australasia and Antarctica. They are perennial plants, either herbaceous, dying back in winter (most temperate species) or evergreen (some tropical species, and the temperate Equisetum hyemale). They mostly grow 0.2-1.5 m tall, though E. telmateia can exceptionally reach 2.5 m, and the tropical American species E. giganteum 5 m, and E. myriochaetum 8 m.

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PLoS Medicine: New Articles

PLoS Medicine Issue Image | Vol. 6(6) June 2009
Tue, 30 Jun 2009 07:00:00 -0000
Clean water should be recognized as a human right. At the March 2009 United Nations meetings coinciding with the World Water Forum, a declaration that would recognize water as a basic human right was defeated. In this month's Editorial, the PLoS Medicine Editors argue that access to clean water should be declared a basic human right for three reasons. First, access to clean water can substantially reduce the global burden of disease caused by water-borne infections. Second, the privatization of water—as witnessed in Bolivia, Ghana, and other countries—has not effectively served the poor, who suffer the most from lack of access to clean water. Third, the prospect of global water scarcity—exacerbated by climate change, industrial pollution, and population growth—means that no country is immune to a water crisis.Image Credit: Rudhach at flickr.com
Seasonal Hunger: A Neglected Problem with Proven Solutions
Bapu Vaitla et al. Tue, 30 Jun 2009 07:00:00 -0000
Clean Water Should Be Recognized as a Human Right
Tue, 30 Jun 2009 07:00:00 -0000
Can We “Hedge” against the Development of Antiviral Resistance among Pandemic Influenza Viruses?
David K. Shay et al. Tue, 30 Jun 2009 07:00:00 -0000
David K. Shay and Benjamin Ridenhour discuss a modeling study predicting that stockpiling a secondary antiviral for use early in a flu pandemic can forestall resistance to the primary stockpiled drug.
Pralidoxime in Acute Organophosphorus Insecticide Poisoning—A Randomised Controlled Trial
Michael Eddleston et al. Tue, 30 Jun 2009 07:00:00 -0000
In a randomized controlled trial of individuals who had taken organophosphorus insecticides, Michael Eddleston and colleagues find that there is no evidence that the addition of the antidote pralidoxime offers benefit over atropine and supportive care.
What Is the Optimal Therapy for Patients with H5N1 Influenza?
Nicholas J. White et al. Tue, 23 Jun 2009 07:00:00 -0000
Nicholas White discusses optimal dosing of oseltamivir, Robert Webster and Elena Govorkova discuss combination antiviral therapy, and Timothy Uyeki discusses clinical care of patients with H5N1.

EurekAlert! - Biology

Study identifies how tamoxifen stimulates uterine cell growth and cancer
Thu, 02 Jul 2009 00:00:00 -0400
(University of California - San Francisco) University of California - San Francisco researchers have identified a new "feed-forward" pathway linking estrogen receptors in the membrane of the uterus to a process that increases local estrogen levels and promotes cell growth.
'Genetic arms race' between bacteria, viruses subject of stimulus grant
Thu, 02 Jul 2009 00:00:00 -0400
(Michigan State University) The oceans teem with microscopic bacteria that produce much of Earth's oxygen as they absorb carbon dioxide greenhouse gas. But fast-mutating viruses also populate the seas, attacking marine bacteria in an ages-old evolutionary arms race. A Michigan State University researcher will probe that ancient dynamic against the backdrop of environmental and climate change, and the pivotal role played by aquatic bacteria in maintaining the Earth's biological balance.
Learning from locusts
Thu, 02 Jul 2009 00:00:00 -0400
(Queen's University) A similarity in brain disturbance between insects and people suffering from migraines, stroke and epilepsy points the way toward new drug therapies to address these conditions.

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