Quick Facts

Quick facts

• Originally from South Africa, Arum Lily (Zantedeschia aethiopica) is a tall fleshy herb with big, dark green, arrowhead-shaped leaves and large white funnel-shaped 'arum-type' flower structures with a central yellow spike.
• It is a common ornamental garden plant that has escaped from cultivation in temperate areas and to south-east Queensland.
• Arum Lily has become a widespread weed, invading mainly damp habitats
• A weed in in pastures, wetlands and forest, roadsides and urban areas
• All parts of the plant are toxic to humans, stock and pets.
• Control by physical and herbicides, plants has underground tubers that re-sprout and grow if not fully removed or killed.
• Follow-up and a combination of treatments are required for effective control.

What Does It Look Like?

What is it?

Arum Lily (Zantedeschia aethiopica) is a robust, clump-forming, fleshy soft perennial herb growing to 1.5 m high. It has a stout rootstock or short, thick underground stem (rhizome) with white, somewhat fleshy, finely branched roots. There is often a dense cluster of several large, knobby tuber-like rhizomes and many smaller tuber-like nodules (rhizomatous offsets). The large arrowhead-shaped leaf blades are glossy dark green to somewhat dull, leathery in texture, to 600 mm long and 300 mm wide, with a prominent midrib and a tip that is bent downwards or curls towards the underside of the leaf. Arising directly from the basal rhizome, the thick, fleshy leaf stalks are up to about 800 mm long, narrowly winged at their base, and exude a sticky sap when broken (Jessop 1986; Hay 1993; Conn 1994; Curtis & Morris 1994; Moore 1997; Parsons & Cuthbertson 2001; Sainty & Associates 2003).

The arum-type flower structure has a central spike (the spadix) to 90 mm long bearing tiny, tightly packed pale yellow to orange-yellow flowers (male flowers above, female below). This is surrounded by a white to ivory (sometimes with green shading) funnel-like bract (the spathe) to 260 mm long terminating with a pointed, recurved tip. The spathe is split to the base on one side with overlapping edges spreading in the upper part. The thick and fleshy flower stalk is as long as or slightly longer than the leaves (Jessop 1986; Hay 1993; Conn 1994; Curtis & Morris 1994; Moore 1997; Parsons & Cuthbertson 2001; Sainty & Associates 2003).

The fruits are irregularly globular berries, 5-10 mm long, clustered in the lower part of the central spike. The immature berries are green or yellowish, turning orange when ripe. They contain several to sometimes many yellowish brown or yellowish orange seeds that are about 3 mm in diameter (Jessop 1986; Hay 1993; Conn 1994; Curtis & Morris 1994; Moore 1997; Parsons & Cuthbertson 2001; Sainty & Associates 2003).

For further information and assistance with identification of Arum Lily contact the herbarium in your state or territory.

Flower colour

White and Yellow

Growth form (weed type/habit)

Herb

Where it currently grows? Preferred habitat

Arum Lily is naturalised in many parts of southern Australia. It grows in open to semi-shaded conditions in damp or marshy areas in wasteland, rubbish dumps, abandoned habitation sites, pastures, market gardens, freshwater wetlands, disturbed creeklines, waterways (commonly on stream banks), floodways, drains, gullies and irrigation ditches as well as in bushland, warm-temperate rainforest and sand dune heath (Sainty & Jacobs 1981; Scott & Wykes 1997a; Blood 2001; Parsons & Cuthbertson 2001; Sainty & Associates 2003; Richardson et al. 2006). Keighery (1997) describes in more detail the range of habitats and locations invaded by Arum Lily in Western Australia.

Arum Lily prefers subtropical to temperate climates but has a wide tolerance: tropical to cold areas, sun to shade conditions, frost to -10^oC (if less than five days of frost per year), water-logging for short periods with up to 30 cm of water over the rootstock, wind, and salt (Blood 2001). Its distribution inland may be limited by frost. It thrives in sandy soil with a periodically high watertable (Sainty & Associates 2003) but also commonly occurs on rich friable soils (Parsons & Cuthbertson 2001).

Are there similar species?

'Arum Lily' is used loosely as the common name for both the true arum lilies (Arum species) and the calla lilies, Zantedeschia species (Parsons & Cuthbertson 2001). Although commonly known as the Arum Lily or Calla Lily, it is not a lily at all but an Aroid (plants in the  family Araceae) with its brilliant white spathe (floral bract) surrounding the central pale yellow spadix (floral spike) bearing tiny flowers (POWO 2019).

One look-a-like is the he garden plant and escapee Arum italicum (Italian Arum or Aaron's Rod), from southern Europe. This  can be distinguished from Arum Lily by its smaller size, its whitish to yellowish leaf veins, a yellowish green hooded spathe (which is mainly white in Arum Lily) and orange-red to scarlet berries (Conn 1994; Shepherd 2004). There are several other species of Zantedeschia grown in home gardens, but these are not known to have escaped from cultivation (see Keighery 1997), apart from the widely sold, popular Zantedeschia aethiopica cultivar 'Green Goddess' that has been recorded from a few sites around the Adelaide HIls (AVH 2021).

When not flowering, Arum Lily could be mistaken for similarly leaved plants such as the cultivated Elephant's Ear (Caladium bicolor) and Native Cunjevoi (Alocasia brisbanensis); Italian Arum or Aaron's Rod (Arum italicum); Taro (Colocasia esculenta);  Philodendron; and other pants in the Ariod (same) family as Zantedeschia.

Why Is It A Weed?

What are its impacts?

Arum Lily (Zantedeschia aethiopica) was included in the list of 71 species that were nominated by state and territory governments for assessment as Weeds of National Significance (WONS). Following an assessment process, Arum Lily was not included as one of the 20 WONS. However, it remains a weed of potential national significance. It is a weed of agriculture, and is increasingly being recognised as a significant environmental weed, especially of damp and riparian areas, and of degraded seasonal wet natural  and urban areas, especially in peri-urban areas along creek lines, drains and seasonal damp areas. Found in gardens, sometimes originally planted. Dense infestations can completely eliminate pasture species or displace native species in bushland.  Infestations are generally confined to areas along rivers, creeks or swampy sites. Arum lily forms dense stands that may displace all species within the understorey layer. These infestations can block the flow of small streams, creaks and drains. Arum Lily is a problem for agriculture where it competes with pasture and is a health hazard for stock, being especially toxic to cattle. It is also poisonous to pets, and humans causing eczema and irritant dermatitis and is especially toxic to children causing fatalities.

Agriculture: Arum Lily can form large spreading clumps. It is a problem for agriculture where it competes with pasture – dense infestations can completely replace pasture species (Parsons & Cuthbertson 2001) – and is a health hazard for stock, being especially toxic to cattle (Groves et al. 2005). The tuber-like roots and rhizomes, leaves, flowers (especially the yellow spike), fruit and seeds are poisonous, as well as being a skin and eye irritant to humans, livestock and pets (Shepherd 2004; Lloyd & Dodd 2006; Richardson et al. 2006).

Native ecosystems: However, it is increasingly being recognised as a significant environmental weed, which invades native vegetation and achieves dominance along watercourses and swampy habitats (Scott & Wykes 1997a). Dense clumps of Arum Lily crowd out native species affecting the biodiversity of natural areas, especially by replacing the native understorey. In wet, swampy habitats it can be extremely troublesome as it impedes water flow (Hussey et al. 1997).

Urban areas: A weed in urban gardens, seasonal damp urban areas and abandoned sites, creek lines and drains, and disturbed areas such as roadsides. The tuber-like roots and rhizomes, leaves, flowers (especially the yellow spike), fruit and seeds are poisonous, as well as being a skin and eye irritant to humans, livestock and pets (Shepherd 2004; Lloyd & Dodd 2006; Richardson et al. 2006).  Arum lily can also be toxic to dogs, cats and birds. If you think you have affected animals contact your vet. In humans causes eczema and irritant dermatitis (Shepherd 2004). The plant has caused fatalities in humans and stock and is especially toxic to children (Parsons & Cuthbertson 2001; Sainty & Associates 2003). Symptoms of poisoning include swelling and burning of the lips, mouth, throat and tongue, acute gastritis (stomach pain) and diarrhoea, causing exhaustion, shock and death (Lamp & Collet 1989; Parsons & Cuthbertson 2001; Shepherd 2004; Lloyd & Dodd 2006). Toxicity is due to calcium oxalate and the alkaloid coniine (Shepherd 2004). Further information on poison properties and poisoning is provided by Aplin (1966), Everist (1964, 1974), Covacevich et al. (1987), the Child Accident Prevention Foundation of Australia and the U.S. Food & Drug Administration Poisonous Plant Database. 

If poisoning occurs and:

• the patient is unconscious, unresponsive or having difficulty breathing dial 000 or get to the emergency section of a hospital immediately.
• the patient is conscious and responsive call the Poisons Information Centre on 13 11 26 or your doctor.
• If going to a hospital take a piece of the plant for identification.

How does it spread?

Arum Lily spreads by both seed and root fragments (Weeds Australia undated).

There may be 50-500 seeds per flower head and up to 5 000 seeds per square metre in a dense stand of plants. The seeds germinate readily, though they do not usually remain viable for more than about 4 months. The seeds are spread by water, birds, foxes, livestock, contaminated soil, machinery, and in dumped garden waste (Panetta 1988; Moore 1997; Plummer 1997; Uren 2000; Blood 2001; Parsons & Cuthbertson 2001; Sainty & Associates 2003 WEEDeck H10).

Natural spread by rhizome growth or expansion is usually localised and less than 30 cm per year (Moore 1997). However, the plant can be spread rapidly from initial sites of introduction by rhizome fragments, which can travel long distances through garden refuse disposal, cultivation and earthworks.

What is its history in Australia?

Arum Lily was introduced to Australia as an ornamental plant for horticulture and was widely promoted in nursery catalogues in Victoria from the 1850s to 1880s.  Arum lily was grown at the Adelaide Botanic Gardens by 1858 and was first recorded as naturalised in South Australia in 1903, at Waterfall Gully (Government of South Australia 2015). It was introduced into Western Australia by immigrants and floriculturists who were looking for plants suited to the Mediterranean climate of the area. Despite its potential as a significant weed, Arum Lily is still available from nurseries in many states as a garden plant, and is still popular in the florist trade, being traditionally associated with funerals (Groves et al. 2005).

How To Manage It?

Best practice management

Arum Lily (Zantedeschia aethiopica) can be hard to control because of its large, hardy root system. Efforts should be repeated over several years to run down the plant’s root system. Successful weed control requires follow up after the initial efforts. This means looking for and killing regrowth or new seedlings. Using a combination of control methods is usually more successful (DPI NSW 2019).  Scattered plants of Arum Lily are best removed physically, but it is important to remove all roots and tubers. Larger infestations may be treated with chemically.

Chemical control: Larger infestations may be treated with herbicide chemically. Leaves and stem are shiny  Seed production can be prevented by spraying plants before fruits ripen (Weber 2003). Herbicides should be applied when the plants are growing actively, usually in August or September before flowering has finished (Parsons & Cuthbertson 2001). Herbicide is effective when applied between June and September or October, but this can depend on the chemical and time of flowering. Follow-up application programs may be necessary after a year or two to treat regrowth and seedlings (Weber 2003; Lloyd & Dodd 2006; Department of Agriculture and Food Western Australia). Also see (DPIRD 2021; DPI NSW 2019;  Invasive Species Unit, Biosecurity SA 2018) Please see the Australian Pesticides and Veterinary Medicines Authority (APVMA) for chemical information http://www.apvma.gov.au .

Please see the Australian Pesticides and Veterinary Medicines Authority for chemical information http://www.apvma.gov.au 

Non-chemical control: Physical control:  Scattered plants of Arum Lily are best removed physically, but it is important to remove all parts of the plant to stop or reduce regrowth. Seedlings are relatively inconspicuous and make control difficult (Uren 2000). Mechanical control: Mechanical removal is only effective if all the root fragments are removed. Multiple rotary hoeing over a few years provides control. 

Does it have a biological control agent?

NO

When does it grow? (lifecycle/growth calendar)

The seeds of Arum Lily germinate in late autumn to winter. Seedling growth is slow at first as the fleshy rootstock and rhizome take time to develop. Young plants continue to grow during summer if moisture is available but become dormant in early winter. New leaves appear in late winter or early spring. Seedling plants may not flower until the third or fourth year, while established plants with mature rhizomes flower at about the same time or soon after the new leaves appear (Moore 1997; Uren 2000; Parsons & Cuthbertson 2001).

Flowering can be between June and February but is mainly from August to November. Some blooms may be found at most times of the year (Hussey et al. 1997).

After flowering, the flower stems collapse and the developing seeds ripen as the spathe dries out. Top growth often dies off by late summer. The rhizomes continue developing until the plant becomes dormant in early winter (Parsons & Cuthbertson 2001).

Plants grown from seed take several years to develop large rhizomes. In dense infestations there can be up to 100 t/ha of rhizomes (Moore 1997). The thick hardy rhizomes allow the plant to avoid unfavourable conditions of heat, cold, drought, and even chemical sprays by becoming dormant (Plummer 1997; Scott & Wykes 1997a).

Where Is It Found?

Which states and territories is it found?

NSW, QLD, SA, TAS, VIC, WA

What areas within states and territories is it found?

Arum Lily is widely naturalised in temperate regions of Australia.

In New South Wales it is mainly found in coastal eastern areas (mainly south from Gosford),

In Queensland it has also been reported as a garden escape near urban areas of Brisbane in south-eastern Queensland (Hay 1993; Keighery 1997; Scott 1997a; Parsons & Cuthbertson 2001; Groves et al. 2005).

In South Australia it is common in temperate areas, especially so in and around Adelaide to the Adelaide Hills area, the Fleurieu Peninsula , and also found in the south-east of the State near coastal and damp areas, on the southern Eyre Peninsula, and on Kangaroo Island.

In Tasmania it is a weed around the south-west of the island in and around Hobart, and in some other near coastal areas norther of the island.

Victoria is is widespread around Melbourne and surrounding areas, and coastal areas of southern Victoria.

In Western Australia, Arum Lily is found from Northampton to Esperance in south-western Western Australia. Arum Lily is well adapted to the Mediterranean climate of south-western Australia, where it grows and spreads vigorously. It is a particularly serious weed along creek lines and in wet areas, pastures and natural bushland (Keighery 1997; Plummer 1997; Scott 1997a; Sainty & Associates 2003).

Arum Lily has not become widely naturalised in any other region of the world, despite being grown around the world as an ornamental (Scott 1997a). It is a localised weed in New Zealand, Norfolk Island, China, Africa, Mascarenes, Europe, Azores, Canary Islands, Madeira, and the United States (Scott 1997a, Blood 2001, Weber 2003).

Where does it originate?

Arum Lily is native to Natal and Cape Province in South Africa (Scott & Wykes 1997a).

National And State Weed Listings

Is it a Weed of National Significance (WONS)?

NO

Where is it a declared weed?

SA, WA

Government weed strategies and lists – Weeds Australia

Is it on the National Alert List for Environmental Weeds?

NO

Government weed strategies and lists – Weeds Australia

Is it on the Agricultural Sleeper List?

NO

Government weed strategies and lists – Weeds Australia

Names And Taxonomy

Main scientific name

Zantedeschia aethiopica

Other scientific names (synonyms)?

• Calla aethiopica L.
• Richardia africana Kunth

Does it have other known common name(s)?

Calla Lily, White Arum Lily, Lily of the Nile, Egyptian Lily, Lily, Jack in the Pulpit, Florist's Calla, Garden Calla, Pig Lily, Trumpet Lily, St Joseph's Arum Lily, Funeral Flower, Death Lily, Varkblom (South Africa)