Invasive alien species represent a grave threat to India's globally significant biodiversity, agricultural productivity, and public health. These are non-native organisms—encompassing plants, animals, and microbes—that, once introduced, establish themselves and proliferate rapidly, causing devastating ecological and economic consequences. These species disrupt native plant communities, alter ecological processes, and affect sectors such as agriculture, forestry, and protected area management. An assessment report, compiled by the National Biodiversity Authority for the Ministry of Environment, Forests and Climate Change, Government of India, is crucial for framing the national management strategies, identifying species based on their known impacts (such as biodiversity loss, economic loss, and health hazards), and tracking their continued range extension across various Indian ecosystems. With globalization, climate change, and anthropogenic disturbances, the risk and spread of invasive plant species have accelerated, making monitoring and management critical for conservation.

Diversity and distribution of invasive plants in India

India hosts a rich diversity of invasive alien plant species across ecosystems. An inventory documented 1059 invasive species, belonging to 587 genera and 142 families, with most species originating from South America, North America and Europe. Protected areas and forest reserves are particularly affected, with studies documenting 41 major invasive plant species across 54 protected areas. Grasslands, coastal wetlands, and tropical deciduous forests are also vulnerable to invasions. Field surveys have also identified first records of species like Hypoestes phyllostachya in North India, indicating that invasions continue to spread into new regions. To map species distribution and identify invasion hotspots, tools such as MaxEnt modelling and remote sensing have been used. Another powerful tool called DNA barcoding has emerged for rapid identification of invasive plants, allowing faster and more reliable detection compared to traditional morphology based approaches.

Drivers and mechanisms of invasion

The spread of invasive plants is driven by climatic conditions, anthropogenic factors, and biological traits. Climate anomalies in temperature and precipitation strongly correlate with invasive species distribution. Human activities such as road construction, fires, and habitat modification create dispersal pathways and disturbances that favour invasive plant species. Biological traits, including high reproductive rates, dispersal abilities, and fungal endophyte associations, contribute to the successful establishment and expansion of invasive plants. Future climate scenarios predict further expansion of species such as Ageratum conyzoides, Ipomoea carnea, and Mikania micrantha, underscoring the need for predictive modelling to guide conservation planning.

Ecological impacts

Invasive plant species have profound ecological impacts that alter both the composition and function of ecosystems. In Manas National Park, the invasion by Chromolaena odorata and Mikania micrantha has been linked to a decrease in native plant diversity. Similarly, understorey invasive plant species in Palamau Tiger Reserve suppress tree seedlings and saplings, which poses a significant threat to forest regeneration and overall forest structure. Invasive shrubs such as Ageratina adenophora and Lantana camara exhibit advanced functional traits, including higher specific leaf area, chlorophyll content, nutrient uptake and leaf litter decomposition compared to native shrubs, which facilitates rapid spread and ecosystem alteration. In addition to the ecological effects, these invasions affect herbivore food sources and the livelihood of rural communities dependent on natural resources.

Terrestrial ecosystems This table lists 54 terrestrial plant species (flora) that are invasive in India.

+ Terrestrial Plant Invasive Alien Species (54 Species) S.No. Scientific name Common name 1. Abutilon crispum (L.) Brizicky Bladder Mallow 2. Acacia auriculiformis L. Northern black wattle 3. Acacia dealbata Link Silver wattle 4. Acacia mearnsii De Willd. Black wattle 5. Ageratina adenophora (Spreng.) King & H. Rob. Crofton weed or sticky snakeroot 6. Ageratina riparia (Regel)R. M.King & H. Rob. Creeping crofton weed 7. Alternanthera bettzickiana (Regel) G. Nichols Red Calico plant 8. Alternanthera brasiliana (L.) Kuntze Brazilian joy weed 9. Alternanthera ficoidea P. Beauv. Joseph's coat 10. Alternanthera paronychioides St. Hil. Smooth joy weed 11. Alternanthera pungens Kunth. Khaki weed 12. Alternanthera tenella Colla Calico plant 13. Antigonon leptopus Hook. & Arn. Coral vine 14. Argemone mexicana L. Mexican poppy 15. Bidens pilosa L. Black Jack 16. Cabomba caroliniana A. Gray Carolina fanwort 17. Cannabis sativa L. Hemp/ Marijuana 18. Centrosema molle Benth. Butterfly-pea 19. Cestrum aurantiacum Lindl Orange cestrum 20. Chromolaena odorata (L.) King & Robin. Siam weed 21. Cirsium arvense (L.) Scop. Canada thistle 22. Lepidium didymum L. Lesser swinecress 23. Cryptostegia grandiflora R. Br. Rubber vine 24. Cuscuta chinensis Lam. Dodder 25. Cytisus scoparius (L.) Link Scotch broom 26. Dactylandra welwitschii Hook. f. Badi Aankh 27. Evolvulus nummularius (L.) L. Round leaf Bindweed 28. Dinebra retroflexa (Vahl) Panz. Viper grass 29. Diplachne fusca (L.) P.Beauv. Brown flowered swamp grass 30. Dysphania ambrosioides Mosyakin & Clemants Mexican tea 31. Erigeron bonariensis L. Horseweed/ Butterweed 32. Erigeron canadensis L. Canadian horseweed 33. Mesosphaerum suaveolens (L.) Kuntze Pig nut 34. Ipomoea eriocarpa R. Br. Purple morning glory 35. Ipomoea carnea Jacq. Bush Morning Glory/Shrub Ipomoea 36. Lantana camara L. Lantana 37. Muntingia calabura L. Jamaican cherry 38. Leucaena leucocephala (Lam.) de Wit False/Horse tamarind 39. Maesopsis eminii Engl. Umbrella-tree 40. Mikania micrantha Kunth Mile-a-minute 41. Mimosa diplotricha C. Wight ex Sauvalle var. Giant sensitive plant 42. Mimosa pigra L. Cat claw mimosa 43. Opuntia dillenii Haw. Prickly pear 44. Opuntia elatior Miller Prickly pear 45. Parthenium hysterophorus L. Congress weed 46. Cenchrus purpureus (Schumach.) Morrone Elephant grass 47. Neltuma juliflora (Sw.) Raf. Mesquite 48. Pueraria montana var. lobata (Willd.) Sanjappa & Pradeep Kudzu 49. Senna spectabilis (DC.) Irwin & Barneby Calceolaria shower 50. Solanum elaeagnifolium Cavanilles Silverleaf nightshade 51. Solanum mauritianum Scop. Bugweed 52. Sphagneticola trilobata (L.) Pruski Singapore daisy 53. Typha angustifolia L. Lesser bulrush 54. Ulex europaeus L. Common gorse

Aquatic ecosystems This table includes all 56 species across aquatic plants, inland fishes, marine species, and microbes found in freshwater/brackish water environments.

+ Invasive Alien Species in Aquatic Ecosystems (56 Species) S.No. Group Scientific name Common name Aquatic Plants (8 Species) 1. Aquatic Plant Alternanthera philoxeroides (Mart.) Griseb. Alligator weed 2. Aquatic Plant Pontederia crassipes Mart. Water hyacinth 3. Aquatic Plant Ipomoea carnea Jacq. Pink morning glory 4. Aquatic Plant Lemna perpusilla Torr. Minute duckweed 5. Aquatic Plant Lythrum salicaria L. Purple loosestrife 6. Aquatic Plant Marsilea quadrifolia Common Water Clover 7. Aquatic Plant Myriophyllum aquaticum (Vell.) Verdc. Parrot's feather 8. Aquatic Plant Salvinia auriculata Aubl (syn. S. molesta) Butterfly fern Inland Fishes (14 Species) 9. Inland Fish Clarias gariepinus African catfish 10. Inland Fish Cyprinus carpio Common carp 11. Inland Fish Gambusia affinis Western Mosquito fish/ Topminnow 12. Inland Fish Gambusia holbrooki Eastern Mosquito fish 13. Inland Fish Mylopharyngodon piceus Black carp 14. Inland Fish Oreochromis mossambicus Mozambique tilapia 15. Inland Fish Oreochromis niloticus Nile tilapia 16. Inland Fish Poecillia reticulata Guppy 17. Inland Fish Pterygoplichthys disjunctivus Vermiculated sailfin catfish 18. Inland Fish Pterygoplichthys multiradiatus Sucker mouth armored cat fish 19. Inland Fish Pterygoplichthys pardalis Amazon sailfin catfish 20. Inland Fish Pterygoplichthys anisitsi Paraná Sailfin Catfish 21. Inland Fish Pygocentrus nattereri Red Piranha 22. Inland Fish Aristichthys nobilis Bighead Marine Species (19 Species) 23. Marine Algae Kappaphycus alvarezii Elkhorn sea moss 24. Marine Algae Monostorma oxyspermum Seaweed 25. Marine Scyphozoa Phyllorhiza punctata (Lendenfield 1884) Phyllorhiza puncta Lendenfield, 1884 26. Marine Scyphozoa Pelagia noctiluca (Forsskal, 1775) Pelagia noctiluca Forsskal, 1775 27. Marine Anthozoa Carijoa riisei Snowflake coral / Branched pipe coral 28. Marine Anthozoa Tubastrea coccinea (Lesson, 1829) Orange soft coral 29. Marine Ctenophora Beroe ovata (Bruguiere, 1789) 30. Marine Ctenophora Beroe cucumis (Fabricius, 1780) 31. Marine Ctenophora Vallicula multiformis (Rankin, 1956) 32. Marine Bivalve Mytilopsis sallei (Recluz, 1849) Caribbean false mussel 33. Marine Bivalve Perna perna (Linnaeus, 1758) 34. Marine Hydrozoa Ectopleura crocea (Agassiz, 1862) Pink-mouth hydroid 35. Marine Polycheates Ficopomatus enigmaticus (Fauvel, 1923) Australian tube worm 36. Marine Polycheates Lumrineris japonica (Marenzeller, 1879) 37. Marine Amphipods Jassa marmorata Holemes, 1905 38. Marine Decapods Penaeus vannamei Boone, 1931 39. Marine Bryozoa Membranipora membranacea (Linnaeus, 1767) Coffin box 40. Marine Ascidian Microcosmus curvus (Tokioka, 1954) Scaly tunicate 41. Marine Ascidian Didemnum candidum Savigny, 1816 Aquatic Microbes (Freshwater/Brackish) (15 Species) 42. Microbe (Fungus) Aphanomyces invadans 43. Microbe (Fungus) Enterocytozoon hepatopenaei 44. Microbe (Bacteria) Edwardsiella tarda 45. Microbe (Bacteria) Flavobacterium Sp 46. Microbe (Virus) White spot syndrome Virus (WSSV) 47. Microbe (Virus) Infectious Hypodermal and Haematopoietic Necrosis Virus (IHHNV) 48. Microbe (Virus) Yellow head virus (YHV) 49. Microbe (Virus) Infectious myonecrosis virus (IMNV) 50. Microbe (Virus) Monodon Baculovirus (MBV) 51. Microbe (Virus) Hepatopancreatic parvovirus (HPV) 52. Microbe (Virus) Laem Singh Virus 53. Microbe (Virus) Carp edema virus 54. Microbe (Virus) Cyvirus cyprinidallo2 55. Microbe (Virus) Ranavirus 56. Microbe (Virus) Tilapia Lake virus

Agriculture ecosystems