June 2011 Water Soldier aloides

WHAT IS IT? A vigorous submerged and emergent aquatic that forms dense stands of vegetation Native to Europe and northwest Asia but not yet recorded in Australia. A common ornamental water garden and aquarium species globally, that can become a serious weed when it escapes or is recklessly dumped in waterways Known also as: water aloe, pineapple plant, and crabs claw Stratiotes aloides L. Credit Photo by Jerzy Opiola. http://commons.wikimedia.org/wiki/Stratiotes_aloides

WHY IS IT A PROBLEM? Forms dense stands of floating vegetation and excludes submerged and other floating riparian flora Destroys aquatic fauna habitat Clogs waterways, drains and irrigation systems Believed to have allelopathic (toxic) effects on plankton Dense mats hinder recreational activities such as boating and fishing Sharp sawtooth-edged can cause injury to swimmers or people who handle this plant S. aloides L. Credit Photo by Velela. http://commons.wikimedia.org/wiki/Stratiotes_aloides

What are State Alert Weeds? These are invasive weeds that are not known to be in South Australia, or if present, occur in low numbers in a restricted area, and are still capable of being eradicated. An Alert Weed would pose a serious threat to the State’s primary industries, natural environments or human health if it became established here. All Alert Weeds are declared under the Natural Resources Management Act 2004: their transport and sale are prohibited (Sect. 175 and 177), must be destroyed (Sect. 182), and if found on your land their presence must be notified to NRM authorities (Sect. 180) – refer overleaf.

DESCRIPTION A perennial, that is free floating in summer, and submerged in winter. The 40 cm long leaves are sword-shaped and very brittle with spines along the margins, and form a rosette. White 3-petalled emerge from the centre of the rosette, and develop into pulpy berries. Plants become buoyant in summer during flowering because new leaves contain air pockets, but as the leaves mature, they become waterlogged and the plant sinks below the water in autumn where it will remain for most of the year. Roots are either attached or floating freely and can grow to a depth of 5 m. S. aloides L. . Credit Photo by Velela http://commons.wikimedia.org/wiki/Stratiotes_aloides HOW IT SPREADS Reproduces mainly by vegetative means, as mature plants produce plantlets which detach and are carried downstream to take root in other locations. Plants also produce seed encased in a berry-like fruit, so that when the plant submerges again the seeds float downstream, but is this method of spread is less common.

HABITAT Widely grown as an ornamental so the native range is now obscure. In Seed: S.Hurst @ USDA-NRCS PLANTS Database Europe it is found in sheltered backwaters, ponds, ditches and nutrient rich water bodies.

ORIGIN Native to Central Europe and northwest Asia, it was introduced and has established into Western Europe.

DISTRIBUTION IN AUSTRALIA Current: Not yet naturalised or cultivated in Australia.

Potential: Has the potential to invade freshwater ponds, lakes and dams in Australia. Its potential in South Australia is unknown.

HOW IT MAY ARRIVE DISTRIBUTION Illegal importation as an aquarium ornamental. Current distribution based on herbarium records

Potential distribution based WHAT CAN YOU DO? on climate modelling Be on the alert for this plant using this Fact Sheet as a guide. If you see a suspicious plant that may be this State Alert Weed, please report it to your local Natural Resources Management (NRM) Board (contact details at www.nrm.sa.gov.au). For more information on weeds, including Alerts, contact your local NRM Board or visit either www.pir.sa.gov.au/biosecurity (phone 08 8303 9620) or www.weeds.org.au.

Disclaimer: This publication is provided for the purpose of disseminating information relating to scientific and technical matters. The Government of South Australia does not accept liability for any loss and/or damage, including financial loss, resulting from the reliance upon any information, advice or recommendations contained in this publication. The contents of this publication should not necessarily be taken to represent the views of the participating organisations.