Invasive Species Compendium

Detailed coverage of invasive species threatening livelihoods and the environment worldwide


Clothing, footwear and possessions (pathway vector)



Clothing, footwear and possessions (pathway vector)


  • Last modified
  • 13 July 2017
  • Datasheet Type(s)
  • Pathway Vector
  • Preferred Scientific Name
  • Clothing, footwear and possessions (pathway vector)
  • Overview
  • Being attached to an individual person’s clothing or footwear is never the only means by which a plant is dispersed, and is unlikely even to ever be the most important means. It is a secondary means at most; more commonly a minor one. It will al...

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Preferred Scientific Name

  • Clothing, footwear and possessions (pathway vector)

International Common Names

  • English: human epizoochory; human-mediated dispersal (HMD)


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Being attached to an individual person’s clothing or footwear is never the only means by which a plant is dispersed, and is unlikely even to ever be the most important means. It is a secondary means at most; more commonly a minor one. It will also be primarily involved in local spread, and only in exceptional circumstances, in international introductions. However, it has been shown to be important in specific areas where other pathways are uncommon, such as uninhabited islets, e.g. in the Galapagos and the sub-Antarctic where frequently visiting researchers are a significant risk (Whinam et al., 2005) or national parks or other protected areas with a regular inflow of (eco) tourists.


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Summary of organism types or species introduced

Many invasive plants could be inadvertently transported by individual people, and thorough research could unearth very many examples. This datasheet presents 21 examples of plant species that have been recorded as likely or possibly dispersed by attaching themselves to clothes and footwear. 

Emex australis and Emex spinosa have hard, thorny achenes that lie on the ground so that one thorn is always pointing upwards. They share the common name 'three-corner jack' and the spines are slightly reflexed so that they can hook onto passing objects, and the erect habit of the plant would encourage dissemination by this method. Attachment of the achenes to the tyres of vehicles, aircraft and machinery is the main method of spread, and allows the seeds to be transported long distances, though they are also dispersed on the soles of shoes (Lemerle, 1996). The spines of E. spinosa are shorter and less robust than those of E. australis, which may explain the slower rates of spread of E. spinosa within Australia. Although E. spinosa achenes are less likely than E. australis achenes to impale and then remain attached to broad, flat rubber surfaces such as the soles of shoes, their smaller size allows them to wedge between the treads of shoes and tyres. 

The spiny fruits of the false puncture vine (Tribulus cistoides) are well equipped for dispersal by wild and domestic animals, and also on human clothes and footwear. The large and small spines on the fruit are arranged at different angles so that, no matter how the seed falls, one of the spines always points upward to meet the unwary foot, hoof or vehicle tyre (Holm et al., 1977) which gives rise to another common name, 'caltrop', the spiked metal ball thrown under the feet of horses in mediaeval warfare. The common puncture vine (Tribulus terrestris) may have been disseminated across the world in the wool of European sheep (Holm et al., 1977) and could also be carried on clothes or shoes. 

Seed of garlic mustard (Alliaria petiolata) is transported by humans, potentially great distances, through mud on the soles of shoes. This is indicated by the observations of A. petiolata at woodland and park entrances, and its lining the edges of footpaths and woodland hiking trails in parts of North America. 

Cheatgrass or downy brome (Bromus tectorum) has barbs on the lemma, palea and awns which are very effective in aiding seed dispersal, seeding in animal fur and also human clothing, especially in socks (WSSA, 2003). 

The burs of southern sandbur (Cenchrus echinatus) seed heads can become firmly attached to clothes and the coats of animals by the barbed spines (Cardenas et al., 1972). 

Seeds of several thistles such as Cirsium arvense can be carried to new locations by sticking to the clothes and shoes of humans, and to the fur and feet of animals (Holm et al., 1991). 

The common ragwort (Senecio jacobaea) is reported to be dispersed by 'humans and their animals' (Schmidl, 1972) and S. vulgaris is also transported attaching itself to clothes, shoes, etc. (McHenry et al., 1990). 

The seeds of crofton weed (Ageratina adenophora) are known to attach themselves, often in mud, to clothes of agricultural workers as well as tourists, hikers, and especially to farm machinery. 

Two knapweeds, Centaurea diffusa and Centaurea stoebe subsp. micranthos, are considered to have been spread by attaching themselves to shoes in North America (Watson and Renney, 1974). 

Dispersal of the common or Scotch broom (Cytisus scoparius) and the Montpellier broom (Genista monspessulana) is thought to occur by the movement of seed in mud attached to all-terrain vehicles and ramblers' boots (Parsons and Cuthbertson, 1992; Peterson and Prasad, 1998). 

The leafy spurge (Euphorbia esula) can be spread by casual contact and dispersed by human activity, and soils contaminated by leafy spurge seeds may adhere to shoes, cars and farming equipment. The ripe fruits of the sun spurge (Euphorbia helioscopia) split explosively to scatter seeds around the plant, from where they may be further spread in irrigation and flood waters, in mud on vehicles, boots and animals and in plant trash, hay and straw. 

Seeds of Senna occidentalis can be spread in mud sticking to animal hooves, footwear, farm machinery and other vehicles (Parsons and Cuthbertson, 1992). 

Seed of the prostrate knotweed (Polygonum aviculare) may be dispersed in mud on footwear or tyre treads (Grime et al., 1988). 

Dog fennel (Anthemis cotula) achenes may occur in mud or soil caked onto animal hooves or hide, in the cuffs of trousers, or in animal faeces (Kay, 1971) though these are not considered common means of dispersal. 

The seeds of purple loosestrife (Lythrum salicaria) are likely to be dispersed in mud adhering to aquatic wildlife or via consumption by waterfowl, or attached to livestock, all-terrain vehicle tyres and human footwear, although there is no direct evidence to support any of these potential pathways (Thompson et al., 1987). 

Humans are also thought to be minor dispersal agents of seeds or achenes of Siam weed (Chromolaena odorata). 

Principal processes

Fruit or seed have generally evolved one of a number of specific adaptations, such as hooks on part of the fruit itself, or fruit that are covered by a persistent calyx equipped with hooks or persistent styles with hooked tips. Seeds that fall into trouser turn-ups or are stuck in mud to clothes or footwear need no such characteristics, however. Some species have a form or habit that appears well-adapted to promoting adhesion to passing animals (humans now included) such as an erect form and position of the fruits. 

The ability to stay attached is also important to guarantee the distance travelled. Wichmann et al. (2009) studied how many seeds are carried by humans on shoes of two plant species. Over half of all seeds fell off within 5 m, but some were regularly still attached to shoes after 5 km. Semi-mechanistic models suggested primary dispersal by wind and secondary dispersal by humans, and that walking humans can disperse seeds to very long distances, up to at least 10 km. 

Geographical routes and corridors

On a local scale, corridors follow footpaths, tracks, roads, etc. They also follow the 'paths' of ecologists, researchers or eco-tourists, which could be considered as a significant subset of people responsible for epihomochory. 

Human-mediated history

Humans have inadvertently carried seeds on their hair, hides, clothes and footwear since the earliest times. However, the scale of this has increased with a greater number of people travelling ever-greater distances, but it still remains only a minor means of plant introduction and spread.

Species Transported by Vector

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SpeciesNotesLong DistanceLocalReferences
Acacia saligna (coojong)Seeds mostly fall directly to the ground and may be transported further by water or people Yes Yes Cronk and Fuller (1995)
Acanthiophilus helianthi (fly, capsule)Cut flowers. Yes
Acanthospermum australe (spiny-bur) Yes Yes
Acanthospermum hispidum (bristly starbur)Achenes adhere to clothing and baggage Yes
Achatina fulica (giant African land snail) Yes
Achlysiella williamsiCarrying sugarcanes Yes
Achyranthes aspera (devil's horsewhip) Yes Yes Lange et al. (2004)
Aculops fuchsiae (Fuchsia gall mite)Possible Yes Koehler et al. (1985)
Adelges tsugae (hemlock woolly adelgid) Yes
Adiantum raddianum (delta maidenhair fern) Yes Yes
Aegilops cylindrica Yes Yes
Aeginetia indica (forest ghost flower)Not mentioned in references but could be a possible way of seed movement Yes
Ageratina adenophora (Croftonweed)Attached to clothing Yes
Ageratum conyzoides (billy goat weed)Dispersed by attaching to clothes. Yes BioNET-EAFRINET (2016)
Ageratum houstonianum (Blue billygoatweed)Seeds attach easily to clothes. Yes Yes Johnson (1971)
Aleurodicus dispersus (whitefly)Air travel with viable plant material Yes Asiwe et al. (2002)
Alternanthera philoxeroides (alligator weed) Yes Yes
Amaranthus palmeri (Palmer amaranth)Possible from agriculture fields Yes Yes CropLife (2019)
Ambrosia confertiflora Yes
Anastrepha fraterculus (South American fruit fly)Fruit in case or handbag. Yes
Anastrepha obliqua (West Indian fruit fly)Fruit in case or handbag. Yes
Anastrepha striata (guava fruit fly)Fruit in case or handbag. Yes
Anastrepha suspensa (Caribbean fruit fly)Fruit in case or handbag. Yes
Aphanomyces astaci Yes Oidtmann et al. (2005)
Aphelenchoides fragariae (strawberry crimp nematode)With ornamentals Yes
Aphelenchoides ritzemabosi (Chrysanthemum foliar eelworm)With flowers and cuttings Yes
Apiognomonia errabunda (anthracnose) Yes
Argemone mexicana (Mexican poppy)Seeds dispersed in mud adhering to footwear Yes Mankeleja et al. (2014)
Austrocylindropuntia cylindrica (cane cactus) Yes
Austrocylindropuntia subulata (Eve’s needle cactus) Yes
Austropuccinia psidii (myrtle rust)Spores Yes Yes Carnegie and Cooper (2011); Langrell et al. (2003)
Avipoxvirus Yes
Avocado sunblotch viroid (avocado sun blotch) Yes
Bactrocera carambolae (carambola fruit fly)Fruit in case or handbag. Yes
Bactrocera correcta (guava fruit fly)Air baggage Yes
Bactrocera cucumis (cucumber fruit fly)Fruit in cases or bags Yes
Bactrocera cucurbitae (melon fly)Fruit in case or handbag Yes
Bactrocera facialisFruit in case or handbag. Yes
Bactrocera frauenfeldi (mango fruit fly)Fruit in case or handbag. Yes
Bactrocera jarvisi (Jarvis' fruit fly)Fruit in case or handbag. Yes
Bactrocera kirkiFruit in case or handbag. Yes
Bactrocera latifrons (Solanum fruit fly)Fruit in case or handbag. Yes
Bactrocera melanotusFruit in case or handbag. Yes
Bactrocera minax (Chinese citrus fly)Fruit in cases or bags Yes
Bactrocera neohumeralisFruit in case or handbag. Yes
Bactrocera occipitalisFruit in case or handbag. Yes
Bactrocera oleae (olive fruit fly)Fruit in case or handbag. Yes
Bactrocera passiflorae (Fijian fruit fly)Fruit in case or handbag. Yes
Bactrocera psidii (South Sea guava fruit fly)Fruit in case or handbag. Yes
Bactrocera tauFruit in case or handbag. Yes
Bactrocera tryoni (Queensland fruit fly)Fruit in case or handbag. Yes
Bactrocera tsuneonis (Japanese orange fly)Fruit in cases or bags Yes
Bactrocera umbrosaFruit in case or handbag. Yes
Bactrocera xanthodes (Pacific fruit fly)Fruit in cases or bags Yes
Berberis thunbergii (Japanese barberry)Intentional/unintentional transport of seeds Yes
Bergia capensis (white water fire)Possible on clothes and shoes used in rice fields. Yes
Bidens pilosa (blackjack)Seed attached to human clothes Yes Yes Sankaran and Suresh (2013)
blood disease bacterium (blood disease bacterium of banana)Transfer of vegetative germplasm. No documented cases, but very likely that the disease is spread by Yes
Boerhavia coccinea (scarlet spiderling)sticky seeds attach to clothing Yes Jurado et al. (1991)
Boerhavia diffusa (red spiderling)Sticky fruits adhere to clothing Yes PIER (2015)
Bothriochloa ischaemum (yellow bluestem)Seeds Yes Yes Hilty (2014)
Brachypodium sylvaticum (slender false brome)Possible anytime Yes Yes Heinken and Raudnitschka (2002)
Brassica juncea (mustard) Yes Office of the Gene Technology Regulator (2008)
Brassica nigra (black mustard)Via seed, soiled footwear, accidental Yes Yes Cal-IPC (California Invasive Plant Council) (2004)
Brassica tournefortii (African mustard)Seeds Yes Minnich and Sanders (2000)
Bromus secalinus (rye brome) Yes Hilty (2015)
Bromus tectorum (downy brome)Socks Yes
Buddleja davidii (butterfly bush) Yes
Bunias orientalis (Turkish warty-cabbage) Yes
Cactodera cacti (cactus cyst eelworm)Carrying cactus Yes
Calotropis procera (apple of sodom) Yes
Cardamine flexuosa (wavy bittercress)Seeds sticky when wet, adheres to clothes and footwear Yes Yes ISSG (2019)
Cenchrus biflorus (Indian sandbur) Yes Yes
Centaurea solstitialis (yellow starthistle) Yes
Ceratitis capitata (Mediterranean fruit fly)Fruit in case or handbag. Yes
Ceratitis cosyra (mango fruit fly)Cases or bags Yes
Ceratitis punctata (cacao fruit fly)Fruit in cases or bags Yes
Ceratocephala testiculata (bur buttercup)associated with camping activities Yes Yes
Chloris gayana (Rhodes grass)Seeds attached to clothingWeeds of Australia (2020)
Chromatomyia horticola (pea leaf miner)Air/road. Yes
Chromolaena odorata (Siam weed)Shoes, in pockets and bags Yes
Chrysomphalus dictyospermi (dictyospermum scale)With passengers Yes
Citrus leprosis virus C (leprosis of citrus)Infected mite vector is frequently transported in clothes. Yes
Citrus yellow mosaic virus (mosaic of citrus)Budwood Yes
Clavibacter michiganensis (bacterial canker of tomato)Transfer of seeds or seedlings. Yes Yes
Clavibacter nebraskensis (Goss's bacterial wilt and leaf blight)Transfer of seeds. Yes
Clavibacter sepedonicus (potato ring rot)Transfer of tubers. Yes
Cleome viscosa (Asian spiderflower)Sticky seeds Yes Yes
Clerodendrum indicum (Turk's turban) Yes
Clerodendrum speciosissimum (Java glory bower)Rhizome fragments may be accidentally transported in soil stuck to machinery, vehicles, etc Yes Yes
Clidemia hirta (Koster's curse)In mud on boots Yes Yes Peters (2001)
Coniothyrium glycines (red leaf blotch) Yes Hartman et al. (1987)
Cornu aspersum (common garden snail) Yes Yes
Cosmos caudatus (wild cosmos) Yes Yes
Cosmos sulphureus (sulphur cosmos)Seeds are adapted for external attachment and animal dispersal Yes Jansen (2005); PlantPono (2014)
Crassula helmsii (Australian swamp stonecrop) Yes Leach and Dawson (1999); OEPP/EPPO (2007)
Cronartium ribicola (white pine blister rust)Aeciospores Yes
Cryptostegia madagascariensis (Madagascar rubbervine)Seeds Yes Yes PIER (2012)
Curtobacterium flaccumfaciens pv. flaccumfaciens (bacterial wilt of dry beans)Transfer of seeds. Yes Yes Osdaghi et al. (2020)
Cyclosorus parasiticus (parasitic maiden fern)Presumed vector. Often along trails Yes Yes Lindsay and Middleton (2013); Wagner (1950)
Cylindropuntia rosea (hudson pear) Yes Deltoro et al. (2014)
Cynodon dactylon (Bermuda grass) Yes
Cynoglossum amabile (Chinese forget-me-not)Seeds Yes Dave’s Garden (2017)
Cyrtomium falcatum (Japanese holly fern) Yes
Cytisus scoparius (Scotch broom)Seeds Yes Peterson and Raj Prasad (1998)
Dacus ciliatus (lesser pumpkin fly)fruit in cases or bags Yes
Daphnia lumholtziEphippia have structures that act as hooks allowing for easy attachment to clothing and other items Yes Yes Benzie (1988); Dzialowski et al. (2000); Fryer (1996); Havel and Hebert (1993)
Datura metel (Hindu datura) Yes Yes PIER (2014)
Daucus carota (carrot) Yes
Deanolis albizonalis (mango seed borer)Wood material through edible fruits carriage. Yes
Deilephila elpenor (large elephant hawkmoth)Intentionally transported Yes
Dendroctonus valens (red turpentine beetle) Yes
Deparia petersenii subsp. petersenii (Petersen’s lady fern)Spores may contaminate gear Yes
Dichanthium aristatum (angelton bluestem)Possible due to its cultivation for pasture and hay Yes
Didymosphenia geminata (didymo)Potential form of introduction Yes Yes
Digitaria bicornis (Asian crabgrass)Might be carried unintentionally in clothes, shoes, etc., due to small size of seeds Yes Yes Catasús Guerra (2015)
Digitaria fuscescens (yellow crab grass)Possibly carried unintentionally in clothes, shoes, etc. Yes
Dinoderus minutus (bamboo borer) Yes
Diplazium esculentum (vegetable fern)Although no information available, it is possible as it is used as an ornamental Yes
Diprion similis (white pine sawfly) Yes
Ditylenchus africanus (peanut pod nematode)Carrying peanuts Yes
Ditylenchus angustus (rice stem nematode)Carrying rice seeds Yes
Ditylenchus dipsaci (stem and bulb nematode)Carrying bulbs, tubers, etc Yes
Echium plantagineum (Paterson's curse) Yes
Elephantopus mollis (elephant's foot) Yes
Emex australis (Doublegee)Soles of shoes Yes
Emex spinosa (spiny emex)Early explorers Yes
Erigeron bellioides (bellorita)Seeds as contaminant: hitchhiker on footwear Yes Yes Nagata (1995)
Erwinia amylovora (fireblight)Transfer of germplasm. Yes
Foeniculum vulgare (fennel) Yes
Funtumia elastica (West African rubber tree)It is possible that seeds could be carried unintentionally in clothes and other Yes
Fusarium oxysporum f.sp. niveum (Fusarium wilt of watermelon)possible, chlamydospores Yes
Galinsoga parviflora (gallant soldier) Yes Yes Damalas (2008)
Geoffroea decorticans (Chilean palo verde)Sweet pods could be carried by curious travellers. Yes
Gilpinia hercyniae (spruce sawfly) Yes
Globodera pallida (white potato cyst nematode)cysts Yes Yes
Globodera rostochiensis (yellow potato cyst nematode)Cysts Yes Been and Schomaker (2006)
Glyceria maxima (reed sweet-grass)Potential to move seed Yes Yes Parsons and Cuthbertson (1992)
Grapevine leafroll-associated viruses (leafroll disease) Yes
Halyomorpha halys (brown marmorated stink bug)Wintering adults are often found in clothing and other possessions that may be transported. Yes Yes
Helicotylenchus dihystera (common spiral nematode)With plants and soil Yes
Helicotylenchus multicinctus (banana spiral nematode)With banana rhizones Yes
Helicotylenchus pseudorobustus (spiral nematode)With soil Yes
Helminthotheca echioides (bristly oxtongue) Yes New Zealand Plant Conservation Network (2016)
Heracleum sosnowskyi (Sosnowskyi's hogweed)Seeds can get attached to clothing and/or shoes Yes Yes Kabuce (2006)
Heterodera avenae (cereal cyst eelworm)Cysts in soil. Yes
Heterodera glycines (soybean cyst nematode)Cysts in soil. Yes
Heterodera goettingiana (pea cyst eelworm)Cysts as contaminants. Yes
Heterodera oryzae (rice cyst nematode)Cysts in soil Yes
Heterodera oryzicola (rice cyst nematode)Cysts in soil. Yes
Heterodera sacchari (sugarcane cyst nematode)Cysts in soil. Yes
Heterodera zeae (corn cyst nematode)Cysts as contaminants. Yes
Heteropogon contortus (spear grass) Yes University of Hawaii (2009)
Heterotheca grandiflora (telegraph weed)Pappus allows seeds to adhere to clothing Yes Csurhes (2009)
Hiptage benghalensis (hiptage)Ornamental and medicinal uses Yes
Hymenachne amplexicaulis (hymenachne)Seeds potential contaminant on water gear Yes Yes Australian Weeds Committee (2012)
Hypothenemus hampei (coffee berry borer)Adults Yes
Hyptis spicigera (black sesame) Yes Le Bourgeois et al. (2019)
Indigofera spicata (creeping indigo)Shoes Yes Yes Morton (1989)
Ips confusus (pinyon ips) Yes
Isatis tinctoria (dyer's woad)Fruits, probably uncommon form of dissemination Yes Zouhar (2009)
Japanagromyza tristella (soyabean black leaf-miner)Air/road. Yes
Jatropha gossypiifolia (bellyache bush)Seed Yes
Kalanchoe pinnata (cathedral bells) Yes
Lactuca floridana (woodland lettuce) Yes Yes
Launaea intybacea (bitter lettuce)Seeds as contaminants Yes Yes PROTA (2018)
Leifsonia xyli subsp. xyli (sugarcane ratoon stunting disease)Transfer of cuttings. Yes
Leptinotarsa decemlineata (Colorado potato beetle)Possible, but difficult in practice to differentiate from the means of transport. Travellers do not Yes
Leptocybe invasa (blue gum chalcid) Yes
Liriomyza bryoniae (tomato leaf miner)Road/air. Yes
Liriomyza sativae (vegetable leaf miner)Land/sea/air. Yes
Liriomyza trifolii (American serpentine leafminer)Land/sea/air. Yes
Lonicera japonica (Japanese honeysuckle) Yes
Lopholeucaspis japonica (Japanese baton shaped scale) Yes
Ludwigia grandiflora (water primrose) Yes Yes Ruaux et al. (2009)
Ludwigia peploides (water primrose) Yes Yes Ruaux et al. (2009)
Lymantria dispar (gypsy moth) Yes Yes
Lymantria mathura (pink gypsy moth) Yes
Lythrum maritimum (pukamole)Seeds can attach to clothing Yes Anderson et al. (1992)
Lythrum salicaria (purple loosestrife)Boots Yes Thompson et al. (1987)
Maconellicoccus hirsutus (pink hibiscus mealybug)eggs, larvae, nymphs, pupae and adults on infested live plant material; and larvae on people
Marisa cornuarietis (giant ramshorn)Eggs and snails potentially transported on clothing and equipment used in aquatic sports Yes
Martynia annua (tiger's claw)Seeds/“clawed” fruit Yes Yes Weeds of Australia (2016)
Meloidogyne acronea (African cotton root nematode)Eggs and galls in soil. Yes
Meloidogyne arenaria (peanut root-knot nematode)Eggs and galls in soil. Yes
Meloidogyne chitwoodi (columbia root-knot nematode)Eggs in soil. Yes
Meloidogyne decalineata (African coffee root-knot nematode)Eggs and juveniles in soil. Yes
Meloidogyne exigua (coffee root-knot nematode)Eggs and juveniles in soil. Yes
Meloidogyne fallax (false Columbia root-knot nematode)Eggs and juveniles in soil. Yes
Meloidogyne graminicola (rice root knot nematode)Eggs and juveniles in soil. Yes
Meloidogyne hapla (root knot nematode)Eggs and juveniles in soil. Yes
Meloidogyne incognita (root-knot nematode)Eggs and galls in soil. Infested soil on footwear. Yes Yes
Meloidogyne javanica (sugarcane eelworm)Eggs and galls in soil. Yes
Meloidogyne mayaguensisEggs and galls in soil. Yes
Mesembryanthemum crystallinum (crystalline iceplant)Seeds may attach to clothing Yes The Arizona Wildland Invasive Plant Working Group (AZ-WIPWG) (2005)
Mesosphaerum pectinatum (comb bushmint)Seed, frequent Yes Yes
Miconia calvescens (miconia) Yes
Mikania micrantha (bitter vine) Yes Yes
Mimosa casta (graceful mimosa)Spiny fruits Yes USDA-ARS (2012)
Mimosa ceratonia (climbing mimosa)Spiny fruits Yes Yes USDA-ARS (2012)
Mimosa diplotricha (giant sensitive plant)clothing Yes DAF (2016); Parsons and Cuthbertson (1992)
Monochoria hastata (hastate-leaved pondweed)No information available, but possible from rice cultivation practices Yes
Mononychellus tanajoa (cassava green mite)Eggs, crawlers/adults. Common pathway Yes
Mycosphaerella citri (greasy spot)Dead leaves. Yes
Myxobolus cerebralis (whirling disease agent)Myxospores in sediment can be moved on anglers' waders Yes Gates et al. (2008)
Nacobbus aberrans (false root-knot nematode)Eggs and adults as contaminants. Yes
Nemorimyza maculosa (chrysanthemum leaf miner)Cut flowers. Yes
Neodiprion sertifer (European pine sawfly) Yes
Nephrolepis hirsutula (sword fern)Possible, as its used for leis and head protection Yes Bodner and Gereu (1988); Whistler (1988)
Nicotiana tabacum (tobacco)Tiny seeds can be transported in soil, on vehicle tyres, on footwear, etc Yes Yes PIER (2014)
Oplismenus hirtellus subsp. undulatifolius (wavyleaf basketgrass) Yes
Opuntia stricta (erect prickly pear)Any vegetative part and seeds Yes
Oxalis corniculata (creeping woodsorrel) Yes
Paracoccus marginatus (papaya mealybug) Yes Yes Tanwar et al. (2010)
Parentucellia viscosa (yellow glandweed) Yes
Parthenium hysterophorus (parthenium weed) Yes PAG (2000)
Paspalum conjugatum (buffalo grass)Seeds Yes Yes PIER (2018)
Paspalum urvillei (Vasey grass)Possibly from agricultural practices Yes Hitchcock (1936); FAO (2012b)
Passiflora tripartita var. mollissima (banana passionfruit) Yes
Pectinophora scutigera (pink spotted bollworm)In baggage and cotton bolls from Hawaii Yes
Pennisetum pedicellatum (deenanath grass) Yes
Pennisetum polystachion (mission grass) Yes
Phakopsora meibomiae (soybean rust)Urediniospores Yes Yes Hartman and Haudenshield (2009)
Pheidole megacephala (big-headed ant) Yes
Phenacoccus solenopsis (cotton mealybug) Yes Arif et al. (2012)
Phyllophaga smithi (white grub) Yes
Physalis angulata (cutleaf groundcherry)Very often with their seeds Yes Travlos et al. (2010)
Phytophthora alni species complex (alder Phytophthora)Movement of infected soil on shoes (not specifically demonstrated for the alder Phytophthora but known to be important for root phytophthoras) Yes Webber and Rose (2008)
Phytophthora cambivora (root rot of forest trees)Soil on clothing and equipment Yes
Phytophthora kernoviaeSoil on footwear Yes EPPO (2013)
Phytophthora ramorum (Sudden Oak Death (SOD))Soil on clothing and equipment
Phytoplasma aurantifolia (lime witches' broom phytoplasma) Yes
Pilosella aurantiaca (orange hawkweed)Introduction of ornamental plants Yes
Pilosella officinarum (mouse-ear hawkweed)Ornamental Yes
Pineus pini (pine woolly aphid)Air Yes
Piper aduncum (spiked pepper) Yes ISSG (2016)
Plasmodiophora brassicae (club root)Infested soil can be moved on footwear Yes Wallenhammar et al. (2016)
Plutella xylostella (diamondback moth) Yes
Poa annua (annual meadowgrass)Seeds can be dispersed adhered to clothes Yes Yes Holm et al. (1997)
Poa nemoralis (wood bluegrass) Yes
Pomacea canaliculata (golden apple snail) Yes
Pratylenchus brachyurus (root-lesion nematode)With plant material Yes
Pratylenchus coffeae (banana root nematode)With host plants Yes
Pratylenchus goodeyi (banana lesion nematode)Carrying banana for planting. Yes
Pratylenchus loosi (root lesion nematode)With plant material. Yes
Pratylenchus penetrans (nematode, northern root lesion)Carrying planting material. Yes
Pratylenchus thornei Yes
Pratylenchus vulnus (walnut root lesion nematode)With plant material e.g. rose cuttings. Yes
Pratylenchus zeae (root lesion nematode)With planting material. Yes
Prays citri (citrus flower moth) Yes
Pseudelephantopus spicatus (false elephant’s foot) Yes Yes Ward (1975)
Pseudococcus viburni (obscure mealybug)Harvest time, crawlers, on clothes of vineyard workers Yes
Pseudogymnoascus destructans (white-nose syndrome fungus)Movement on clothing, footwear, or equipment (particularly caving equipment) is possible Yes Yes Ballmann et al. (2017); Shelley et al. (2013); Sleeman (2011)
Pseudomonas corrugata (pith necrosis of tomato)Transfer of seeds. Yes
Pseudomonas fuscovaginae (sheath brown rot)Transfer of seeds. Yes
Pteris multifida (spider brake)Although not reported it is a possibility as a result of its cultivation Yes
Pteris tripartita (giant brake)Not mentioned in literature, but a possibility from its cultivation Yes
Pteris vittata (Chinese ladder brake fern)Spores can be transported via clothing and equipment Yes UF/IFAS Center for Aquatic and Invasive Plants (2019)
Puccinia asparagi (asparagus rust) Yes
Puccinia kuehnii (orange rust)Clothes Yes
Punctodera chalcoensisCarrying host plants. Yes
Punctodera punctata (grass cyst nematode)Carrying host plants. Yes
Quadrastichus erythrinae (Erythrina gall wasp) Yes
Rabdophaga saliciperda (shot-hole gall midge) Yes
Radopholus similis (burrowing nematode)With plants Yes
Ralstonia solanacearum (bacterial wilt of potato)Transfer of vegetative germplasm. Yes
Rastrococcus invadens (fruit tree mealybug)Possible transmission on clothes or body. Probably very minor. Yes
Rhagoletis cerasi (European cherry fruit fly)Fruit in case or handbag. Yes
Rhagoletis cingulata (cherry fruit fly)Fruit in case or handbag. Yes
Rhagoletis completa (walnut husk fly)Fruit in case or handbag. Yes
Rhagoletis fausta (black cherry fruit fly)Fruit in case or handbag. Yes
Rhagoletis indifferens (western cherry fruit fly)Fruit in case or handbag. Yes
Rhagoletis mendax (blueberry fruit fly)Fruit in case or handbag. Yes
Rhagoletis pomonella (apple maggot)Fruit in case or handbag. Yes
Rhagoletis ribicola (American currant fruit fly)Fruit in case or handbag. Yes
Rubus fruticosus (blackberry)Intentional/unintentional transport of seeds Yes
Rudbeckia laciniata (cutleaf coneflower) Yes Akasaka et al. (2015)
Salvia occidentalis (West Indian sage) Yes Fern (2014)
Salvia splendens (scarlet sage) Yes Yes Floridata (2014)
Salvinia auriculata (giant salvinia) Yes Yes ISSG (2009)
Scapanes australis (rhinoceros beetle) Yes
Senecio jacobaea (common ragwort)Fruits attached to clothes, shoes, etc. Yes
Senecio vulgarisFruits attached to clothes, shoes, etc. Yes
Senna occidentalis (coffee senna)In mud sticking to footwear Yes Parsons and Cuthbertson (1992)
Senna septemtrionalis (smooth senna)Carried by mud stuck to shoes Yes Yes Weeds of Australia (2014)
Sesbania punicea (red sesbania) Yes
Setaria verticillata (bristly foxtail) Yes Yes
Sida acuta (sida) Yes Smith (2002)
Sida repens (Javanese fanpetals) Yes Yes
Solanum capsicoides (cockroach berry) Yes
Solanum elaeagnifolium (silverleaf nightshade)Ballast and bedding used in railroad cattle cars; easily carried by shoe soles, hooves, machinery Yes Yes
Solanum rostratum (prickly nightshade)Seed-bearing fruit possesses prickly thorns. easily sticks to wool Yes Yes DEPI-AU (2014)
Solidago nemoralis (grey goldenrod)Hypothetical Yes
Soliva sessilis Yes Yes Castro (2006)
Sonchus asper (spiny sow-thistle)Seeds as contaminant Yes Yes GISD (2018)
Sonchus oleraceus (common sowthistle)Contaminant Yes Yes Holm et al. (1977)
Spongospora subterranea f.sp. subterranea (powdery scab)Baggage. Yes
Sporobolus africanus (rat’s tail grass) Yes
Sporobolus pyramidalis (giant rat’s tail grass) Yes
Striga asiatica (witch weed) Yes Yes
Taeniatherum caput-medusae (medusahead wildrye)Seeds get trapped in clothing/footwear Yes Kyser et al. (2014)
Tamarix aphylla (athel)Smuggled flowers, cuttings Yes
Tamarix canariensis (Canary Island tamarisk)Smuggled flowers, cuttings Yes
Tamarix chinensis (five-stamen tamarisk)Smuggled flowers, cuttings Yes
Tamarix gallica (French tamarisk)Smuggled flowers, cuttings Yes
Tamarix parviflora (small-flower tamarisk)Smuggled flowers, cuttings Yes
Tamarix ramosissima (saltcedar)Smuggled flowers, cuttings Yes
Tapinoma melanocephalum (ghost ant)Observed associated in the personal luggage of people entering New Zealand Yes Yes
Taraxacum officinale complex (dandelion)People deliberately importing seeds for own use. Yes
Tecoma stans (yellow bells)Travellers carrying seeds for home cultivation Yes
Tetranychus urticae (two-spotted spider mite) Yes
Thecaphora frezii (peanut smut)Not frequent Yes Yes Marinelli et al. (2010)
Themeda quadrivalvis (grader grass)Contaminant Yes Yes Keir and Vogler (2006)
Tibouchina herbacea (cane tibouchina)Frequent along trails Yes Yes Almasi (2000)
Tomato brown rugose fruit virus (Tomato brown rugose fruit virus) Yes
Toxotrypana curvicauda (papaya fruit fly)Fruit in case or handbag. Yes
Tragus racemosus (stalker bur grass)No information available but possible as the seeds have hooked spines that could attach easily to clothes and footwear Yes PROTA (2020)
Triumfetta bogotensis (parquet bur)Burs attach to clothing Yes Standley and Steyermark (1949)
Triumfetta rhomboidea (diamond burbark)Burs attach to clothing Yes Yes Valkenburg and Bunyapraphatsara (2001)
Triumfetta semitriloba (burweed) Yes
Tylenchorhynchus claytoni (stunt nematode) Yes
Tylenchulus semipenetrans (citrus root nematode)With citrus plants. Yes
Typha domingensis (southern cattail)Achenes with hairs. Yes Parsons and Cuthbertson (1992)
Typha x glauca (hybrid cattail)Fruits with hairs Yes Parsons and Cuthbertson (1992)
Urena lobata (caesar weed)Spiny fruits and barbed seed Yes Yes Langeland et al. (2008)
Urochloa distachya (signal grass)Footwear Yes
Urtica dioica (stinging nettle) Yes Taylor (2009)
Varanus niloticus (Nile monitor)Tanned skin trade Yes Enge et al. (2004)
Ventenata dubia (North Africa grass)When seeds are present Yes Yes
Vincetoxicum rossicum (European swallowwort)Craft items Yes
Vulpia myuros (annual fescue)Seeds Yes Wallace (1997)
Xanthium spinosum (bathurst burr) Yes PIER (2013)
Xiphinema rivesi (dagger nematode) Yes
Xylella fastidiosa (Pierce's disease of grapevines)Bacteria in living vector insects or plants (dormant or non-dormant) Yes
Zeuxine strateumatica (soldier’s orchid)Unintentionally moved in footwear Yes Yes Proctor (1982)
Zinnia peruviana (Peruvian zinnia)Seeds have awns that attach to fur and clothing Yes Yes Torres (1963)


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The accidental spread of plants within an area by people may be unavoidable. However, impacts can be made to reduce the risk of introduction to new areas. Inspection surveys need to be made to assess the level of risk, such as were carried out on people travelling to remote sub-Antarctic locations by Whinam et al. (2005). Following this work, changes were implemented regarding management and logistical arrangement to reduce the risks, which have proved effective. 

Other studies have made similar recommendations regarding simple checks and hygiene, such as Venner (2007) who suggested that road workers carefully remove any plant material from their clothes and footwear to avoid the risk of introduction of invasive species to new areas. Awareness raising is one of the most common means, by educating visitors about the risks and how they can reduce them. Many national parks and protected areas include such warnings on their websites and brochures, asking people to ensure that they have cleaned the mud off their walking boots or shoes, and to check their clothes for the presence of attached seeds, etc. Instituting more checks on individuals at key entry points would be more costly, but more effective. These could be airports, ports, the gates to national parks, etc.


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Ansong M; Pickering C, 2014. Weed seeds on clothing: a global review. Journal of Environmental Management, 144:203-211.

Cardenas J; Reyes CE; Doll JD, 1972. Tropical weeds Vol. 1. Bogota, Colombia: Instituto Colombiano Agropecuario.

Grime JP; Hodgson JG; Hunt R, 1988. Comparative plant ecology. A functional approach to common British species. London, UK: Unwin Hyman Ltd., 679 pp.

Holm LG; Pancho JV; Herberger JP; Plucknett DL, 1991. A Geographical Atlas of World Weeds. New York, USA: John Wiley and Sons.

Holm LG; Plucknett DL; Pancho JV; Herberger JP, 1977. The World's Worst Weeds. Distribution and Biology. Honolulu, Hawaii, USA: University Press of Hawaii.

Kay QON, 1971. Biological flora of the British Isles. Anthemis cotula L. Journal of Ecology, 59:623-636.

Kerr S; Cardenas S; Hendy J, 2004. Migration and the environment in the galapagos: an analysis of economic and policy incentives driving migration, potential impacts from migration control, and potential policies to reduce migration pressure. Motu Working Paper Series, No. 03-17. Wellington, New Zealand: Motu (Economic Research and Public Policy), 188pp.

Lemerle D, 1996. Spiny emex (Emex australis) in the cropping zone of New South Wales. Plant Protection Quarterly, 11(4):154; 6 ref.

McHenry WB; Bushnell RB; Oliver MN and Norris RF, 1990. Three poisonous plants common in pasture and hay: fiddleneck, common groundsel, yellow starthistle. University of California Cooperative Extension Publ. 21483, Berkeley, CA.

Parsons WT; Cuthbertson EG, 1992. Noxious Weeds of Australia. Melbourne, Australia: Inkata Press, 692 pp.

Peterson DJ; Raj Prasad, 1998. The biology of Canadian weeds. 109. Cytisus scoparius (L.) Link. Canadian Journal of Plant Science, 78(3):497-504.

Schmidl L, 1972. Biology and control of ragwort, Senecio jacobaea L., in Victoria, Australia. Weed Research, 12:37-45.

Thompson DQ; Stuckey RL; Thompson EB, 1987. Spread, impact, and control of purple loosestrife (Lythrum salicaria) in North American wetlands. United States Fish and Wildlife Service, Fish and Wildlife Research No.2. Washington DC, USA: United States Department of the Interior.

Venner M, 2007. Control of Invasive Species. Synthesis 363, Synthesis 363., USA: Federal Highway Administration.

Watson AK; Renney AJ, 1974. The biology of Canadian weeds. 6. Centaurea diffusa and C. maculosa. Canadian Journal of Plant Science, 54(4):687-701

Whinam J; Chilcott N; Bergstrom DM, 2005. Subantarctic hitchhikers: expeditioners as vectors for the introduction of alien organisms. Biological Conservation, 121(2):207-219.

Wichmann MC; Alexander MJ; Soons MB; Galsworthy S; Dunne L; Gould R; Fairfax C; Niggemann M; Hails RS; Bullock JM, 2009. Human-mediated dispersal of seeds over long distances. Proceedings of the Royal Society of London. Series B, Biological Sciences, No.1656:523-532.

WSSA, 2003. 1,000 weeds of North America: an identification guide. Lawrence, USA: Weed Science Society of America.


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6/30/2009 Original text by:

Nick Pasiecznik, Consultant, France