Weeds in Australia

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Lantana camara

Description
 

Lantana is a sprawling or scandent shrub or vine normally 1-3 m high, and on rare occassions to 6 m high in favourable conditions, often growing in dense thickets. The stems and branches are normally quadrangular in cross-section when young, often well armed with short recurved prickles and sometimes with glands or glandular hairs. The leaves are in opposite pairs on the stem, with successive pairs borne at right angles to each other. The leaves are ovate to oblong-ovate, about 4-10 cm long, 3-6 cm wide, often covered with rough coarse hairs on the upper surface and strongly aromatic due to glandular hairs. The margins are bluntly toothed. The inflorescence is a dense head of 20-40 brightly coloured flowers, ranging from yellow, orange-yellow, deep orange, deep red, pink, rose-pink to white, often with a variation of colours in each head of flowers and with the flowers having the ability to change colour as they mature. The fruit has many berries, which ripen from green to shiny purple-black and contain one or two pale seeds (CRC 2003).

Lantana is an 'aggregate species', or 'species complex'. There are several natural variants of L. camara across its presumed native range in the tropical Americas, and in addition some hundreds of horticultural colour and habit varieties have been developed around the world, with over 650 varietal names coined (DECC 2007).

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

Seed longevity in the soil is not well documented, but seeds are thought to remain viable for several years under natural conditions. Work in progress suggests an in-soil longevity of at least three and up to five years. Germination rates are reported as being increased by removal of fruit pulp, as occurs with passage through the digestive system of birds and by warm temperatures, light, and high soil moisture. Germination rates even under favourable conditions are sometimes reported as fairly low (<45% or less), but as fruits may set at rates of up to several thousand /m2 there is a considerable soil seedbank (CRC 2003; DECC 2007).

Lantana can resprout from the base if the shoot dies, extending the life of individual plants (CRC 2003).

Distribution:

Lantana is now found across four million hectares of land east of the Great Dividing Range, from Mount Dromedary in southern New South Wales to Cape Melville in northern Queensland. Isolated infestations exist in the Top End of the Northern Territory, around Perth in Western Australia, and on Lord Howe and Norfolk Islands. Although present Australia wide as a garden ornamental, it has not naturalised to any serious extent elsewhere (CRC 2003).

Habit:Shrub, Vine
Key points:
  • Lantana (Lantana camara) is a thicket-forming shrub that has spread from gardens into pastures, woodlands and rainforests on the east coast.

  • It typically invades disturbed land and river margins, extending its range in response to rainfall.

  • It threatens agriculture and pastoral production, forestry and biodiversity of conservation areas, and may be toxic to stock.

  • The highest priority for Lantana control is preventing its spread into northern Australia and west of the Great Dividing Range.

  • Integrated control should combine fire, mechanical, chemical and biological methods, and revegetation.

How it spreads:Lantana spreads in two ways. Layering is a form of vegetative reproduction where stems send roots into the soil, allowing it to quickly form very dense stands and spread short distances. Also, birds and other animals such as foxes consume and pass the seed in their droppings, potentially spreading it over quite large distances. The germination rate of fresh seed is generally low, but improves after being digested (CRC 2003).

Butterflies, bees and other insects are attracted by the nectar and pollinate Lantana flowers. About half of the flowers produce seeds, typically 1-20 seeds on each flower head. Mature plants can produce up to 12 000 seeds every year. Seeds are thought to remain viable for several years under natural conditions (CRC 2003).

Lantana is allelopathic and can release chemicals into the surrounding soil which prevent germination and competition from some other plant species (CRC 2003).

Where it grows:

Lantana can grow in high-rainfall areas with tropical, subtropical and temperate climates. It does not tolerate salty or dry soils, waterlogging or low temperatures (<5 ºC). It thrives on rich, organic soils but also grows on well-drained clay and basalt soils. Sandy soils tend to dry out too rapidly for Lantana unless soil moisture is continually replenished. It has been reported at altitudes up to 1000 m in Queensland (CRC 2003).

Lantana invades disturbed sites, especially open sunny areas, such as roadsides, cultivated pastures and fencelines. From there it can invade the edges of forests, but it does not fare as well under a heavy canopy as it is not very shade tolerant (CRC 2003).

Flower colour:Multi-colour
Distribution map: Weed Distribution Map
Impacts:

Lantana is a Weed of National Significance. It is regarded as one of the worst weeds in Australia because of its invasiveness, potential for spread, and economic and environmental impacts. Lantana forms dense, impenetrable thickets that take over native bushland and pastures on the east coast of Australia. It competes for resources with, and reduces the productivity of, pastures and forestry plantations. It adds fuel to fires, and is toxic to stock (CRC 2003).

Most variants of L. camara in Australia are toxic to domestic livestock (sheep, cattle) to some degree, with only three thought to be consistently non-toxic. There does not appear to be any documentation of palatability and toxicity to native fauna. Toxicity seems likely to be related to genetic factors, not environmental ones. Some toxic reactions have been recorded in humans, especially children (DECC 2007).

Lantana dominance appears to adversely affect the species richness of soil fauna assemblages, such as ants, and decreases the diversity of soil fungi. It can also affect flora diversity by reducing seedling germination and by increasing the chance and severity of fire in plant communities such as dry rainforest. Lantana has been identified as a potential threat to many threatened and endangered plants and animals and a number of endangered ecological communities (DECC 2007).

Origin:

Lantana occurs naturally in Mexico, the Caribbean and tropical and subtropical Central and South America. It is considered a weed in nearly 50 countries (CRC 2003).

History:

The earliest record for Australia is from 1841 in the old Botanic Gardens in Adelaide, South Australia, and cultivated plants are known to have been grown in New South Wales by John Macarthur at Camden Park in 1843. There have been multiple introductions since, mainly in New South Wales and Queensland. It was reported by 1879 as a "most troublesome weed" in Queensland and abundant around Port Jackson, New South Wales (DECC 2007).

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This database is designed to provide information, including biological and ecological, on invasive plant species that are on a national weed list, or are legislated against in a state or territory. While reasonable efforts have been made to ensure the accuracy of the information, no guarantee is given, nor responsibility taken, by the Commonwealth for its accuracy, currency or completeness. The Commonwealth does not accept any responsibility for any loss or damage that may be occasioned directly or indirectly through the use of, or reliance on, the information contained in this database. The information contained in this database does not necessarily represent the views of the Commonwealth. This database is not intended to be a complete source of information on the matters it deals with. For further information on the images contained in the database please contact the copyright owner. All images in the weed identification tool are managed by the Australian Plant Image Index (APII). Various copyright conditions apply for these images. For further information on the copyright conditions of images contained in the database please contact the APII at: photo@anbg.gov.au.