Iris spp.
flag
A shade loving perennial herb up to 1m high with thickened red brown rhizomes or bulb like rootstocks. Flowers various colours, usually yellow or blue, up to 10 cm in diameter, in 2 to 4 flowered, unbranched scapes. They have a perianth and are divided into 6 segments, the outer 3 are reflexed and the inner 3 usually small erect and narrowed to a distinct claw. Flowers from Nov - Dec. Leaves dark green, pointed, sword shaped, leathery, up to 25 mm wide and smell unpleasant when bruised (I. foetidissima). Fruit green, 3 sided capsules about 6 cm long, which split to reveal 3 rows of rounded brown (I. pseudacorus) or bright red (I. foetidissima) seeds each 5 mm in diameter. The capsules persist for several weeks.
The various irises found in New Zealand include stinking iris (I. foetidissima), bearded iris (I. germanica), I. orientalis and the aquatic yellow flag (I. pseudacorus). Other species are grown in gardens. The shape of the flowers is distinctive. Gladiolus are superficially similar.
Grown mainly as garden ornamentals, however I. foetidissima is frequently found around old homestead sites and in farm paddocks. Except in Westland, Fiordland and Southland it is both common and widespread thoughout the North and South Islands. I. germanica and I. pseudacorus are rarer. They all prefer damp spots and will actually grow in waterways.
The toxin is possibly a phenol glycoside - iridin, however the mechanism of action is not known. Some cytotoxic activity has been shown to occur. All parts of the plant (particularly the rhizome) are poisonous, even when dry. The sap of the plant is thought to be irritating to the skin and may occasionally cause blistering.
Pigs, cattle, sheep
Mouth irritation, severe haemorrhagic gastroenteritis.
Cattle: severe purging and high temperatures.
Pigs: bloody diarrhoea, abortion and possible death.
Humans: nausea, violent diarrhoea, and abdominal burning.
Inflammation of the stomach and intestines
History of observed eating of the plant or identifiable plant remains in the gastrointestinal tract post mortem.
Homeria, Moraea, Diplarrhena moraea (Australian native lily) Sisyrinchium micranthum (yellow rush lily)
Prevent further ingestion of the plant and treat symptomatically.
Depends on the quantity ingested and the time prior to treatment. Not usually 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
Parton K, Bruere A.N. and Chambers J.P. Veterinary Clinical Toxicology, 3rd ed. 2006. Veterinary Continuing Education Publication No. 249
12 October, 2007
