Indian plant Ricinus communis among invasive threats to world’s second largest lake

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According to a new report published by the Invasive Species Initiative under the International Union for Conservation of Nature (IUCN) , the Caster oil plant which is native to India is one of the invasive plants that raise a major threat to the second largest and second deepest lake in the world – Lake Tanganyika - shared by  Burundi,Zambia,Tanzania and Democratic Republic of the Congo (DRC) .

Dense Growth of Ricinus communis

The report says that Ricinus communis, commonly known as Castor oil plant in English and Kadalavanakku in Malayalam, is a usual plant found in India. The plant, according to IUCN report, has shown invasive nature in other habitats and is a major invasive threat to Lake Tanganyika.

Lake Tanganyika has at least 250 species of endemic cichlid fish and many endemic water plants. But the presence of invasive plants around the lake is threatening the natural habitat of the lake as well as the existence of native fauna and flora.

The invasive zeal of Ricinus communis

Biological invasion is a wide phenomenon seen across the globe. It happens when a non-native species is introduced to a new environment, and it spreads virulently to cause damage to native organisms. Ricinus communis, due to its invasive nature, now has spread across all the tropical regions, says the report.

According to the study, the invasive nature of the plant makes it capable of displacing native plant species from a habitat. The impact will be more visible in the case of riparian areas and drainages. The seeds of the castor oil plant also give the plant some upper hand among native plants, shows the report.

The Castor oil seeds have a worthy appendage known as caruncle which attracts ants as the major seed dispersal agents for the plant.  Moreover, the seeds are among the first to germinate after a fire season, allowing the plant to have a competitive advantage over other native plants over the fight for resources.

Lake Tanganyika
Image courtesy : Google Maps

The plant is a fast growing suckering perennial shrub and often attains the size of a small tree. Due to this nature, when they colonize in already disturbed habitats, they grow faster, often shade over the native plants and seedlings, gradually weakening the strength of the native plant species.

Major reasons for the spread of the plant

According to the study, the ornamental plant trade is a major source through which the plant has got its grip around Lake Tanganyika . The practice of cultivation for extracting Castor oil is also a reason, points out the study. Apart from these, road building machinery, earth moving equipment and dumped garden waste also spreads the seeds of the plant.

The study which is preliminary in nature is the first of its kind to take place at Lake Tanganyika. It has listed 31 invasive plants which are raising serious threat to the water body.