Review article on <em>Alternanthera philoxeroides</em> (Mart.) Griseb (alligator weed); an invasive plant species in Sri Lanka and its control measures

Abstract

Alligator weed (Alternanthera philoxeroides (Mart.) Griseb) is an invasive weed in different countries of South America, North America, Australia and Asia. It can grow in range of habitats from aquatic to terrestrial environments. It is one of the non-native plants which was invading natural and agricultural eco systems in Sri Lanka and has recorded as a threat to the native species and thereby to the plant bio diversity. It was an accidental introduction to Sri Lanka due to misidentification as a commonly cultivated leafy vegetable A. sessilis (Mukunuwenna). So it is highly possible to include A. philoxeroides in the market samples of leafy vegetables due to this similarity. A. philoxeroides can propagate through vegetative fragmentation and these vegetative propagules can be dispersed by water in aquatic habitats. An over view of all aspects of A. philoxeroides including its geographical distribution and spread in the world, morphology and ecological aspects, environmental impacts, success of the management options used and present status of this weed in Sri Lanka is presented by this article. Management of alligator weed through chemical, biological, and mechanical means are effective up to some extent in Sri Lanka but it is still a problem in many areas Therefore well-planned, long-term mechanism to evaluate the role of different factors which is responsible for rapid infestation is essential to control the weed. Future research should be focused more on integration weed management approaches in both natural and agricultural ecosystems and to identify the weed from its congener, A. sessilis.

Neutral interactions between native Alternanthera sessilis and exotic Alternanthera philoxeroides along a light gradient under tropical climatic conditions

“…It is suspected to been introduced to Sri Lanka unintentionally and rapidly spread via human intervention due to misidentification with the commonly consumed leafy vegetable Alternanthera sessilis (L.) R.Br. ex DC (Dissanayake, 2020). Alternanthera philoxorides was initially encountered in the Southern province of Sri Lanka in 1998 (Dissanayake, 2020).…”

“…ex DC (Dissanayake, 2020). Alternanthera philoxorides was initially encountered in the Southern province of Sri Lanka in 1998 (Dissanayake, 2020). Later, A. philoxeroides has observed to propagate in the Western and Central provinces of the country (EPPO, 2016).…”

“…Furthermore, invasiveness, control, and management of A. philoxeroides have been studied in Australia, New Zealand, and North America where A. philoxeroides endangers the biodiversity of aquatic ecosystems (Tanveer et al, 2018). However, relatively few studies have investigated interactions between these two species in tropical climatic conditions prevalent in countries like Sri Lanka (Dissanayake, 2020). It is necessary to investigate their interactions under tropical climatic conditions because previous studies suggest that A. philoxeroides is less invasive in hot tropical climates than in temperate regions (Julien et al, 1995).…”

“…It naturally proliferates in lowlands, semi‐aquatic areas, and riparian ecosystems, and is also commercially cultivated, primarily in waterlogged low‐lying lands adjacent to water bodies. It was suggested that commercial cultivation due to misidentification as A. sessilis accelerated the spreading of A. philoxorides in Sri Lanka (Dissanayake, 2020). Although, the commercial cultivation has been hindered following identification, A. philoxeroides , which was mistakenly cultivated still exists as patches in cultivated lands and is widespread in abandoned muddy areas near commerical A. sessilis cultivations (Dissanayake, 2020).…”

“…It was suggested that commercial cultivation due to misidentification as A. sessilis accelerated the spreading of A. philoxorides in Sri Lanka (Dissanayake, 2020). Although, the commercial cultivation has been hindered following identification, A. philoxeroides , which was mistakenly cultivated still exists as patches in cultivated lands and is widespread in abandoned muddy areas near commerical A. sessilis cultivations (Dissanayake, 2020). Further, it has escaped into natural ecosystems (wetlands, riparian eco systems and other low lying areas), and monocultural colonies are often observed in roadside ditches (Dissanayake, 2020).…”