Variable shrub native to tropical America introduced to most of the tropical and sub-tropical regions. Forms extensive impenetrable thickets in disturbed areas but is also found in the understorey of open forests.
Two to five meter tall shrub. Erect in the open and scrambling in scrubland.
L. camara is a highly variable species. It has been cultivated for over 300 years and now has hundred of cultivars and hybrids. These belong mostly to the Lantana camara complex. Cultivars can be distinguished morphologically (variation in: flower size, shape and colour; leaf size, hairiness and colour; stem thorniness), physiologically (variation in: growth rates, toxicity to livestock) and by their chromosome number and DNA content.
Flowers are yellow, later turning orange then red and remain on the axillary inflorescence for three days. The flowers, when yellow, produce nectar and are pollinated by butterflies. The species is an obligate outcrosser. It is unclear whether apomixis occur. The fleshy drupe is 3-6 mm in diameter containing 1-2 seeds (1.5 mm long). Fruits mature rapidly and change colour from dark green to black. A number of bird species and sometimes sheep and goats disperse the seeds. Flowering and fruiting throughout the year with a peak during the first two months of the rainy season. Heavy fruit production produced yearly.
The alkaloid rich leaves are virtually immune to herbivory. It can spread vegetatively. Stems and roots coppice freely following herbicidal treatment. Slashing and burning stimulate suckering. Allelopathic effect induced by L. camara inhibits growth of other vegetation as well as seed germination. It has low tolerance for boggy soils, saline soils and is susceptible to frost.
Thrives in open and disturbed areas as well as in open natural vegetation. Being somewhat shade-tolerant and it can become the dominant understorey shrub in open forests.
Ornamental plant which was often used for hedges and erosion control. Twigs are used as fuel. A number of minor uses include seeds as lamb food, biogas production when its straw is mixed with dung, and medicinal purposes.
Native to Central and South America. Original distribution unclear due to the introduction of a number of ornamental varieties. Species poorly investigated.
In the West Indies it is found in dry thickets.
In Central America L. camara is a weed in a number of crops and is common in pastures, waste areas and roadsides.
Many insect species attack flowers, flower stalks, leaves, stems, shoots and roots. Their impact on shrub vigour and seed set is not known.
L. camara has been introduced throughout the tropics and subtropics as an ornamental, often used as a hedge plant. It is regarded as a cosmopolitan weed and in many countries it has been declared a noxious weed. Mostly introduced during the late 19th century but a number of cultivars and forms were subsequently introduced.
L. camara forms extensive, dense and impenetrable thickets in forestry plantations, orchards, pasture land, waste land and in natural areas. The rapid spread of L. camara is associated with human induced disturbance. Fruits are widely dispersed by many birds including introduced species. On the Galapagos L. camara started to spread soon after its introduction. In scrub areas of New Caledonia the plant scrambles through the vegetation not unlike climbers. However in taller forests it is absent and is rarely found in large treefall gaps. In areas where natural fires occur they stimulate thicker regrowth.
Tolerates a wide range of climates. In Australia L. camara tolerates a mean annual rainfall from 4000 mm to less than 1000 mm. Found between sea level and nearly 1000 m on Hawaii and higher in East Africa. Its distribution is affected by soil type, but grows well on poor soils.
A wide array of regions and vegetation types at the exception of closed forests and wet communities.
No reports of important pests and diseases.
The spread of L. camara on the Galapagos islands is seen as a threat to bird breeding populations and plant communities containing rare endemics. Its extensive seed production favours rat populations. In New Caledonia, by increasing fire intensity as a result of its large dry biomass as well as its smothering effect, it displaces natural scrub communities.
L. camara poisoning in cattle and sheep have often been recorded. Children have died after eating unripe berries. The dense thickets, particularly those of the thorny variety, deter human access. In forestry it tends to over-run young plantations and prevents access to older plantations. In Indian sandalwood forests the shrub competes with the tree crop as well as favours the spread of the sandal spike disease. In some mountainous areas (Tanzania, India) the presence of L. camara was once considered as a good erosion preventing ground cover. It encroaches agricultural land, reduces the carrying capacity of pastures and is a weed in many agricultural crops. In New Caledonia following reproduction the climbing stems dry out and the dead material falls to the ground increasing fire susceptibility. In Tanzania L. camara can be considered as a serious health threat, as its thickets provide breeding grounds for Tsetse flies infected with trypanosomes of domestic animals.
Since the turn of the century, biological control has been attempted in many parts of the tropics with varying degrees of success as different cultivars display differences in susceptibility to insect herbivores. Greater success appears to have been achieved in drier areas. In Uganda the introduction of Teleonemia scrupulosa Stal, used harmlessly in Australia and Fiji, was less successful as it attacked the crop Sesamum indicum L. Chemical control is expensive and cleared areas are rapidly reinfected by seedlings and stem and roots freely coppice. Mechanical control can be effective , particularly where land is cleared, but is labour intensive and requires continual follow-up treatment to remove roots and seedlings.
Differs from native plants by a combination of fast growth rates, allelopathy, fire tolerance, and great variability (i.e. numerous cultivars).
There are no indications that any major differences exist between the invaded and native ranges.
Pierre Binggeli
October 1999