Lantana camara/ Spanish Flag is a hardy, tropical bush with red-yellow (the colours of the flag of Spain) flowers. It is native to tropical America and was introduced as an ornamental garden hedge in India and other parts of the world. Lantana camara is today considered by the International Union for Conservation of Nature (IUCN) as one of world’s 100 most invasive species and is among 10 worst weeds!! It grows well on well drained soils and is drought resistant. It grows in dense thickets and resists all attempts to defeat it by cutting and burning. In India, Lantana has invaded forests and open spaces all over the country. It typically occupies the edges of forests and parts where natural forest cover has been disturbed. It is rarely successful in undisturbed forest areas covered by tree canopies. Thus, the weed often gets the initial foothold by colonizing the narrow-belt of forest that is cleared along the roads and forest tracks in order to improve access.
Lantana produces huge volume of seeds that germinate quickly on being dispersed by the bush birds. It can completely blanket the ground cover and suppress the native species in the understorey, not allowing natural regeneration thereby reducing biodiversity. Some smaller shrubs and grasses do, however, manage to thrive under the thickets and are in fact saved from foraging by the overlying lantana!
Lantana is toxic to grazing animals thus reducing availability of food to the ungulates that reduces availability of prey for the carnivores. Lantan poisoning leads to the animal getting depressed and losing appetite as the jaundice sets in. The animal gets highly photosensitive.
The flower heads are dome-shaped and consist of several, four-petalled, tiny tubular-shaped brightly coloured flowers. The ‘fragrant’ flowers attract butterflies in abundance (most humans dislike the pugent, citrus smell of the flowers!). The flowers also attract hummingbirds. Lantana produces berries that are juicy and a glossy, blue-black when ripe. Birds like the bulbul and the robin feed on the lantana berries, unharmed by the plant chemicals.
The lantana bush is woody and dry in summers and burns fiercly during forest fires of summer season. The forest fires in lantana infested Morni hills have over the years diminished the population of pheasants like jungle fowls, patridges, francolins, hares, porcupines, monitor lizards and other forms of life that lay eggs in the scrub or are unable to flee in time. The lantana fed forest fires are more severe and cause destruction of trees, especially those with thin barks. The fires also reduce soil-moisture content and cause premature leaf fall thereby leading to indirect tree-deaths. Lantana quickly regenerates with the advent of the monsoons and covers the area laid waste by the fire.
Ayesha E. Prasad has estimated the extent and severity of Lantana camara infestation in the 5000 sq.km moist deciduous forest area of the Bandipur Tiger Reserve in the foothills of Western Ghats in Karnatka using satellite imagery and field studies. As per her findings, nearly half of the forest reserve is infested with moderate levels of Lantana with only a small area being completely free of infestation. The story would be very similar for the entire Shivalik hill range in the north including the Morni hills.
- Impact of Lantana camara, a major invasive plant, on wildlife habitat in Bandipur Tiger Reserve, southern India; Ayesha E. Prasad, Nature Conservation Foundation