Equisetum arvense
Mare's tail
Primitive perennials with tough, creeping roots. Stems die down every year. Cone like fruiting bodies are on separate stems (30cm) to the “leaves” (50cm).
There is only supposed to be one sp. in NZ, but I have seen a related sp. growing on the Coromandel coast. Several other species. are grown in gardens.
Locally common on river banks and lake edges. It has become a problem in some places because it spreads rapidly by its creeping roots and is resistant to most weedkillers.
High silicate content can cause mechanical damage; poisoning probably caused by thiaminase.
Not reported in NZ; horses cattle and sheep overseas (usually from eating contaminated hay).
Rare.
Wasting, weakness, incoordination, diarrhoea.
No specific findings, but can include jaundice, degenerative changes in brain, liver and kidney, lung congestion, gut inflammation and meningitis.
History, evidence of ingestion.
Large doses of thiamine.
Recovery good if treated, slow if not. Rarely fatal.
Conner H.E. The Poisonous Plants In New Zealand. 1992. GP Publications Ltd, Wellington
Cooper M R, Johnson A W. Poisonous Plants and Fungi in Britan: Animals and Human Poisoning. Her Majesty’s Stationary Office. London. 1998
