# Flora of the Houtman Abrolhos

This is a list of the terrestrial flora of the Houtman Abrolhos. Only vascular plants are listed — there have been some collections of mosses, liverworts and lichens from the Houtman Abrolhos, but no information has been published on these non-vascular groups.
The distribution of each species within each island group is provided. A list of islands is provided for species that occur on fewer than ten islands in a group; for species that occur on ten or more islands in a group, an island count is provided. Islands without a formally gazetted name are referred to by informal names, given in quotation marks.
A grey background indicates a naturalised species.
| Scientific name | Common name | Distribution | Distribution | Distribution | Remarks | Image |
| Scientific name | Common name | Wallabi Group (45 islands) | Easter Group (34 islands) | Pelsaert Group (41 islands) | Remarks | Image |
| Aizoaceae |||||||
| Carpobrotus sp. | | | Rat I. | | | |
| Carpobrotus virescens | Coastal Pigface | 13 islands | 25 islands | 23 islands | | |
| Disphyma crassifolium subsp. clavellatum | Round-leaved Pigface | Pigeon I. | Leo I., Rat I. | | | |
| Mesembryanthemum crystallinum | Iceplant | 40 islands | 18 islands | 30 islands | Naturalised | |
| Sesuvium portulacastrum | | | Campbell I. | | | |
| Tetragonia decumbens | Sea Spinach | | Crake I., Keru I., White I., Wooded I. | | Naturalised | |
| Amaranthaceae |||||||
| Ptilotus divaricatus | Climbing Mulla Mulla | East Wallabi I. | | | | |
| Ptilotus eriotrichus | | East Wallabi I., West Wallabi I. | | | | |
| Ptilotus gaudichaudii | | East Wallabi I. | Serventy I. | | | |
| Ptilotus obovatus | Cotton Bush | East Wallabi I. | | | | |
| Ptilotus villosiflorus | | West Wallabi I. | | | | |
| Anthericaceae |||||||
| Thysanotus patersonii | | East Wallabi I., North I., Pigeon I., Seagull I., West Wallabi I. | | | | |
| Apiaceae |||||||
| Apium annuum | | East Wallabi I., West Wallabi I. | Alexander I., Campbell I., Serventy I. | | | |
| Apium prostratum | Sea Celery | Tattler I. | | Middle I. | | |
| Daucus glochidiatus | Australian Carrot | East Wallabi I., North I., Pigeon I., West Wallabi I. | Campbell I., Keru I., White I. | Middle I. | | |
| Hydrocotyle diantha | | East Wallabi I., West Wallabi I. | Rat I. | Basile I., Middle I. | | |
| Petroselinum crispum | Parsley | | Little Rat I., Rat I., Roma I. | | Naturalised | |
| Trachymene pilosa | Native Parsnip | East Wallabi I. | | | | |
| Apocynaceae |||||||
| Alyxia buxifolia | Dysentery Bush | East Wallabi I., Seagull I. and West Wallabi I. | | | | |
| Asclepiadaceae |||||||
| Sarcostemma viminale subsp. australe | | "Eagle Point Islet", East Wallabi I., Oystercatcher I., Pigeon I., Seagull I. and West Wallabi I. | | Basile I., Middle I. | | |
| Asphodelaceae |||||||
| Bulbine semibarbata | Leek Lily | "Eagle Point Islet", East Wallabi I., Little Pigeon I., North I., Pigeon I. and West Wallabi I. | Rat I. | Middle I., Pelsaert I. | | |
| Asteraceae |||||||
| Actinobole condensatum | | East Wallabi I., North I., West Wallabi I. | | | | |
| Actites megalocarpa | Dune Thistle | Little Pigeon I., Long I., Oystercatcher I., Pigeon I., Seagull I. | | Pelsaert I. | | |
| Angianthus tomentosus | Camel-grass | East Wallabi I. | | | | |
| Brachyscome ciliaris | | East Wallabi I., North I., Pigeon I. | Little Rat I. | | | |
| Brachyscome iberidifolia | | East Wallabi I. | | | | |
| Calocephalus aervoides | Woolly Beauty-heads | East Wallabi I., West Wallabi I. | | | Rated "Priority Three - Poorly Known Taxa" in the Department of Environment and Conservation's Declared Rare and Priority Flora List. | |
| Chthonocephalus tomentellus | | West Wallabi I. | | | Rated "Priority Two - Poorly Known Taxa" in the Department of Environment and Conservation's Declared Rare and Priority Flora List. | |
| Conyza bonariensis | Flaxleaf Fleabane | Little Pigeon I., Pigeon I. | Bushby I., Little Rat I., Rat I., Roma I. | | Naturalised | |
| Conyza sumatrensis | Tall Fleabane | | Rat I. | | Naturalised. Harvey et al. (2001) lists C. albida, but this is now a taxonomic synonym of C. sumatrensis. | |
| Erigeron karvinskianus | | | | Gun I., Murray I. | Naturalised | |
| Euchiton sphaericus | | East Wallabi I., North I. | Rat I. | | | |
| Gnaphalium indutum | Tiny Cudweed | East Wallabi I. | Leo I. | | | |
| Helichrysum luteoalbum | Jersey Cudweed | East Wallabi I., North I., Turnstone I., West Wallabi I. | Little Rat I., Rat I. | | Naturalised. Harvey et al. (2001) lists Pseudognaphalium luteoalbum, but this is now a nomenclatural synonym of Helichrysum luteoalbum. | |
| Hypochaeris glabra | Smooth Catsear | | | Basile I. | Naturalised | |
| Lactuca saligna | Wild Lettuce | Pigeon I. | | | Naturalised | |
| Olearia axillaris | Coastal Daisybush | Eastern I., East Wallabi I., Long I., North I., Pigeon I., Turnstone I., West Wallabi I. | Campbell I. | | | |
| Podotheca angustifolia | Sticky Longheads | North I., West Wallabi I. | | | | |
| Reichardia tingitana | False Sowthistle | | Campbell I., Rat I. | Basile I., Middle I. | Naturalised | |
| Senecio glossanthus | Slender Groundsel | East Wallabi I., North I., West Wallabi I. | | | | |
| Senecio pinnatifolius | | 23 islands | 17 islands | 16 islands | Harvey et al. (2001) lists S. lautus but this name has been misapplied in Western Australia to S. pinnatifolius. | |
| Sonchus oleraceus | Common Sowthistle | 20 islands | 19 islands | 16 islands | Naturalised. Harvey et al. (2001) lists both S. oleraceus and S. tenerrimus on four islands, and S. tenerrimus alone on another. However, the latter name is now considered a misapplication against the former in Western Australia, so here the entries for these names have been pooled. | |
| Urospermum picroides | False Hawkbit | 10 islands | 10 islands | Burnett Rock, Burton I., Gun I., Post Office I., Uncle Margie I. | Naturalised | |
| Ursinia anthemoides | Ursinia | | Alexander I., Leo I., Serventy I., White I. | Burnett Rock, Burton I. | Naturalised. | |
| Vittadinia cuneata var. cuneata | Woolly Vittadinia | Akerstrom I., Barge Rock, East Wallabi I., Marinula I., Seagull I., Turnstone I. | | | | |
| Vittadinia sp. | | East Wallabi I. | | | | |
| Avicenniaceae |||||||
| Avicennia marina | White Mangrove | Akerstrom I., "East Mangrove I.", Marinula I., Oystercatcher I., Seagull I., Tattler I., Turnstone I., West Wallabi I. | Alexander I., Campbell I., Keru I., Little Rat I., "Little Stokes I.", Morley I., Serventy I., Suomi I., Wooded I. | 14 islands | | |
| Boraginaceae |||||||
| Cynoglossum australe | Australian Hound's-tongue | East Wallabi I., West Wallabi I. | | | Harvey et al. (2001) lists this species, but according to FloraBase it does not occur in Western Australia. | |
| Echium plantagineum | Paterson's Curse | East Wallabi I. | | | Naturalised; classed as a noxious weed. | |
| Trichodesma zeylanicum | Camel Bush | North I. | | | | |
| Brassicaceae |||||||
| Brassica rapa | | Beacon I. | | | Naturalised | |
| Cakile maritima | Sea Rocket | 10 islands | 13 islands | 12 islands | Naturalised | |
| Hornungia procumbens | Oval Purse | 14 islands | Bynoe I., Leo I., Morley I., Serventy I. | Burton I., Pelsaert I. | Naturalised. Harvey et al. (2001) lists Hornungia procumbens on 13 islands, and Hymenolobus procumbens on another, but the latter name is now considered a synonym of the former. | |
| Lepidium lyratogynum | | Eastern I. | Bynoe I., Leo I., Little North I., White I. | | | |
| Lepidium pseudoruderale | | Beacon I., Dakin I., Dick I., Eastern I., Saville-Kent I., Seal I. | | Burnett Rock, Burton I., Coronation I., Jackson I., "Little Jackson I.", Newman I., Pelsaert I., Post Office I., Square I. | | |
| Lepidium puberulum | | Eastern I., "First Sister Islet" | 10 islands | | Rated "Priority Four — Rare Taxa" in the Department of Environment and Conservation's system of Declared Rare and Priority Flora List. | |
| Raphanus raphanistrum | Wild radish | Pigeon I. | Alexander I., Little Rat I., Rat I., Serventy I. | Basile I., Gun I., Murray I., Pelsaert I., Post Office I. | Naturalised | |
| Raphanus sativus | Radish | | Alexander I. | Basile I., Burnett Rock | Naturalised | |
| Sisymbrium irio | London Rocket | | Suomi I. | | Naturalised | |
| Sisymbrium orientale | Indian Hedge Mustard | Beacon I. | Little Rat I., Rat I. | Burnett Rock | Naturalised | |
| Cactaceae |||||||
| Opuntia stricta | Common Prickly Pear | | Rat I. | Basile I. | Naturalised | |
| Campanulaceae |||||||
| Wahlenbergia gracilis | | | Rat I. | | | |
| Wahlenbergia multicaulis | | | Rat I. | | | |
| Capparaceae |||||||
| Capparis spinosa | Coastal Caper | "Eagle Point Islet", East Wallabi I., Little Pigeon I., Oystercatcher I., Pigeon I., Seagull I., Tattler I., Turnstone I., West Wallabi I. | | | | |
| Caryophyllaceae |||||||
| Cerastium glomeratum | Mouse Ear Chickweed | | | Eight I., Three I. | Naturalised | |
| Petrorhagia dubia | Velvet Pink | | Rat I. | | Naturalised. Harvey et al. (2001) lists P. velutina, but this is now a taxonomic synonym of P. dubia. | |
| Polycarpon tetraphyllum | Fourleaf Allseed | East Wallabi I., Little Pigeon I., Pigeon I. | Little Roma I. | Basile I., Jackson I. | Naturalised | |
| Sagina apetala | Annual Pearlwort | East Wallabi I. | | | Naturalised | |
| Silene gallica | French Catchfly | | White I. | | Naturalised | |
| Silene nocturna | Mediterranean Catchfly | | Alexander I., Bynoe I., Little Rat I., Morley I., Serventy I. | | Naturalised | |
| Spergularia diandra | Lesser Sand Spurry | | | Gun I. | Naturalised | |
| Spergularia rubra | Sand Spurry | 12 islands | Little Rat I., Roma I. | Pelsaert I., Three I. | Naturalised | |
| Spergularia sp. 5 Leeman | | | Rat I. | | Harvey et al. (2001) lists S. nesophila, but this is an unpublished manuscript name, which is considered a nomenclatural synonym of the above. | |
| Stellaria media | Chickweed | West Wallabi I. | | | Naturalised | |
| Celastraceae |||||||
| Stackhousia sp. | | West Wallabi I. | | | Harvey et al. (2001) lists this under Stackhousiaceae, but it is now generally treated under Celastraceae. | |
| Stackhousia sp. | | East Wallabi I., North I., West Wallabi I. | | | Harvey et al. (2001) lists this as Stackhousia viminea, but this name has been misapplied in Western Australia against three species: S. clementii, S. muricata and S. intermedia. Harvey et al. (2001) treats Stackhousia under Stackhousiaceae, but it is now generally treated under Celastraceae. | |
| Tripterococcus brunonis | | East Wallabi I. | | | Harvey et al. (2001) lists this under Stackhousiaceae, but it is now generally treated under Celastraceae. | |
| Chenopodiaceae |||||||
| Atriplex amnicola | Swamp Saltbush | | | Gun I., Murray I., Pelsaert I. | | |
| Atriplex bunburyana | Silver Saltbush | | Rat I. | | | |
| Atriplex cinerea | Grey Saltbush | 27 islands | 21 islands | 22 islands | | |
| Atriplex paludosa | Marsh Saltbush | Little Pigeon I., Long I., Mangrove I., North I., Pelican I., Pigeon I., Tattler I., West Wallabi I. | | | | |
| Atriplex paludosa subsp. baudinii | | | Rat I. | | | |
| Atriplex vesicaria subsp. variabilis | Bladder Saltbush | Seagull I. | | | | |
| Atriplex sp. | Saltbush | 17 islands | 10 islands | 18 islands | | |
| Chenopodium album | Fat Hen | | Rat I. | | Naturalised | |
| Chenopodium melanocarpum | Black Crumbweed | East Wallabi I. | | | | |
| Chenopodium murale | Nettle-leaf Goosefoot | Beacon I., North I., Pelican I., West Wallabi I. | Alexander I., Joe Smith I., "Landscope I.", "Nitraria I.", Rat I., Wooded I. | Burton I., Gun I., "Little Jackson I.", Pelsaert I., Square I., Uncle Margie I. | Naturalised | |
| Chenopodium nitrariaceum | Nitre Goosefoot | East Wallabi I., West Wallabi I. | | | | |
| Dysphania plantaginella | | East Wallabi I. | | | | |
| Enchylaena tomentosa | Barrier Saltbush | 26 islands | 11 islands | 17 islands | | |
| Rhagodia baccata | Berry Saltbush | Akerstrom I., East Wallabi I., North I., Oystercatcher I., Pigeon I., Seagull I., Tattler I., Turnstone I., West Wallabi I. | | | | |
| Rhagodia latifolia | | Akerstrom I., "Eagle Point Islet", Little Pigeon I., North I., Pigeon I. | | | | |
| Rhagodia preissii subsp. obovata | | | Little Rat I., Rat I. | | | |
| Rhagodia sp. | | | Rat I. | | | |
| Salsola kali | Prickly Saltwort | Dick I., Eastern I., East Wallabi I., Long I., North I., Seal I., Third Sister, West Wallabi I. | Bynoe I., Campbell I., Crake I., Leo I., Morley I., Rat I. | Basile I., Coronation I., Pelsaert I., Stick I. | Naturalised | |
| Sarcocornia quinqueflora | Beaded Samphire | 17 islands | 19 islands | 15 islands | | |
| Suaeda australis | Seablite | 11 islands | "Nitraria I.", Tapani I., Wooded I. | Newman I., Pelsaert I. | | |
| Tecticornia arbuscula | | East Wallabi I., North I., Pigeon I., West Wallabi I. | | Gun I., Middle I., Murray I., Pelsaert I. | Harvey et al. (2001) listed Sclerostegia arbuscula, but all Sclerostegia were transferred into Tecticornia in 2007. | |
| Tecticornia halocnemoides | Shrubby Samphire | Akerstrom I., Alcatraz I., Barge Rock, East Wallabi I., North I., Pigeon I., Shag Rock, West Wallabi I. | 13 islands | 25 islands | Harvey et al. (2001) listed Halosarcia halocnemoides, but all Halosarcia were transferred into Tecticornia in 2007. | |
| Tecticornia lepidosperma subsp. bidens | | Akerstrom I. | Little Rat I., Rat I. | Lagoon I., Pelsaert I. | Harvey et al. (2001) listed Halosarcia indica subsp. bidens, but all Halosarcia were transferred into Tecticornia in 2007. | |
| Tecticornia sp. | Samphire | West Wallabi I. | | | Harvey et al. (2001) listed Halosarcia sp., but all Halosarcia were transferred to Tecticornia in 2007. | |
| Threlkeldia diffusa | Coast Bonefruit | 33 islands | 19 islands | 20 islands | | |
| Colchicaceae |||||||
| Wurmbea monantha | | East Wallabi I., North I., West Wallabi I. | Alexander I., Serventy I. | | | |
| Convolvulaceae |||||||
| Ipomoea cairica | | | Little Rat I. | | Naturalised | |
| Crassulaceae |||||||
| Bryophyllum delagoense | Mother of Millions | Pigeon I. | Rat I. | | Naturalised. In 2000 this poisonous weed was found to have colonised over half of Rat and Pigeon Islands. | |
| Crassula colorata | Dense Stonecrop | Dick I., Eastern I., East Wallabi I., Long I., North I., Tattler I., West Wallabi I. | 10 islands | Basile I., Burton I., Middle I., Pelsaert I., Stick I. | | |
| Crassula exserta | | | Bynoe I., Campbell I., Leo I., White I. | | | |
| Cotyledon orbiculata | | Dick I., Eastern I., Pigeon I., West Wallabi I. | | | | |
| Cucurbitaceae |||||||
| Cucurbita pepo | | | Rat I. | | | |
| Cunoniaceae |||||||
| Aphanopetalum clematideum | | East Wallabi I. | | | | |
| Cyperaceae |||||||
| Ficinia nodosa | Knotted Club Rush | North I. | | | Harvey et al. (2001) listed Isolepis nodosa, but this species has since been transferred into Ficinia. | |
| Isolepis marginata | Coarse Clubrush | East Wallabi I., West Wallabi I. | | | Naturalised | |
| Dasypogonaceae |||||||
| Acanthocarpus preissii | | "Eagle Point Islet", East Wallabi I., Little Pigeon I., North I., Oystercatcher I., Pigeon I., Seagull I., Tattler I., West Wallabi I. | | | | |
| Dilleniaceae |||||||
| Hibbertia racemosa | Stalked Guinea Flower | East Wallabi I., West Wallabi I. | | | | |
| Epacridaceae |||||||
| Leucopogon insularis | | East Wallabi I., West Wallabi I. | | | | |
| Euphorbiaceae |||||||
| Beyeria viscosa | Pinkwood | East Wallabi I., Oystercatcher I., West Wallabi I. | | | | |
| Euphorbia boophthona | Gascoyne Spurge | Pigeon I. | | | | |
| Euphorbia drummondii | Caustic Weed | East Wallabi I., West Wallabi I. | Little Rat I., Rat I. | Middle I. | | |
| Euphorbia tannensis | | "Eagle Point Islet", Little Pigeon I., North I., Oystercatcher I., Pigeon I., Seagull I., Turnstone I. | | Middle I. | | |
| Euphorbia terracina | Geraldton Carnation Weed | Pigeon I. | Little Rat I., Rat I. | | Naturalised | |
| Phyllanthus calycinus | False Boronia | East Wallabi I., West Wallabi I. | | | | |
| Frankeniaceae |||||||
| Frankenia pauciflora | Seaheath | 11 islands | Bushby I., Campbell I., Little Rat I., Rat I. | Davis I., Gun I., Middle I., Murray I., Pelsaert I., Sweet I. | | |
| Gentianaceae |||||||
| Centaurium erythraea | Common Centaury | | Bushby I., Little Rat I. | | Naturalised | |
| Schenkia australis | | East Wallabi I., North I., Pigeon I., Tattler I., Turnstone I., West Wallabi I. | | Basile I., Gun I., Pelsaert I. | Naturalised. Harvey et al. (2001) lists this as Centaurium spicatum, but this species has been transferred into Schenkia, and the Australian specimens segregated into a new species as S. australis. Harvey et al. (2001) also lists C. maritimum on East Wallabi Island, but this name has been misapplied for C. spicatum in Australia. | |
| Geraniaceae |||||||
| Erodium cicutarium | Common Storksbill | Barge Rock, East Wallabi I., Long I., North I., Pigeon I., West Wallabi I. | Little Rat I., Rat I. | Middle I., Pelsaert I., Square I. | Naturalised | |
| Erodium cygnorum | Blue Heronsbill | East Wallabi I., North I., Pigeon I. | | | | |
| Pelargonium littorale | | East Wallabi I. | | | | |
| Pelargonium zonale | | | Rat I. | | Naturalised. Harvey et al. (2001) lists this species, but FloraBase has no record of it occurring in Western Australia. | |
| Goodeniaceae |||||||
| Scaevola crassifolia | Thick-leaved Fan-flower | East Wallabi I., North I., Seagull I., West Wallabi I. | Campbell I., Rat I., Suomi I. | Pelsaert I. | | |
| Haloragaceae |||||||
| Haloragis trigonocarpa | | East Wallabi I., Pigeon I. | | | | |
| Juncaceae |||||||
| Juncus bufonius | Toad Rush | East Wallabi I., North I., Pigeon I., West Wallabi I. | | | Naturalised | |
| Juncaginaceae |||||||
| Triglochin centrocarpa | | Dick I., Pigeon I., West Wallabi I. | | Gun I., Middle I., Pelsaert I., Three I. | | |
| Triglochin mucronata | | North I., West Wallabi I. | | | | |
| Triglochin muelleri | | East Wallabi I. | | | | |
| Triglochin trichophora | | Barge Rock, East Wallabi I., North I. | Keru I., Rat I., Serventy I. | | | |
| Lamiaceae |||||||
| Westringia dampieri | | East Wallabi I., First Sister, West Wallabi I. | | | | |
| Liliaceae |||||||
| Aloe sp. | | Little Pigeon I. | | | Naturalised | |
| Loganiaceae |||||||
| Phyllangium paradoxum | | West Wallabi I. | | | | |
| Malvaceae |||||||
| Lavatera sp. | | | "Shearwater Islet" | | | |
| Malva preissiana | Australian Hollyhock | 21 islands | 15 islands | 12 islands | Harvey et al. (2001) lists this as Lavatera plebeia, but this is now a synonym of M. preissiana. | |
| Malva linnaei | Cretan Mallow | | Little North I., White I. | | Naturalised according to FloraBase, though not according to Harvey et al. (2001). The latter source lists this as Lavatera cretica, but this is now a synonym of M. linnaei. | |
| Malva parviflora | Marshmallow | East Wallabi I., North I., Pigeon I., West Wallabi I. | Rat I. | Newman I., Sid Liddon I. | Naturalised | |
| Sida spodochroma | | East Wallabi I. | | | | |
| Mimosaceae |||||||
| Acacia didyma | | East Wallabi I. | | | | |
| Myoporaceae |||||||
| Eremophila glabra | Tar Bush | East Wallabi I., West Wallabi I. | | Basile I., Middle I. | | |
| Eremophila deserti | | East Wallabi I. | | | | |
| Myoporum insulare | Blueberry Tree | 27 islands | 22 islands | 17 islands | | |
| Myrtaceae |||||||
| Eucalyptus oraria | Ooragmandee | East Wallabi I. | | | | |
| Onagraceae |||||||
| Epilobium billardiereanum | Glabrous Willow Herb | East Wallabi I. | | | | |
| Orobanchaceae |||||||
| Orobanche minor | Lesser Broomrape | East Wallabi I. | | | Naturalised | |
| Orchidaceae |||||||
| Microtis media | Tall Mignonette Orchid | East Wallabi I. | | | | |
| Microtis sp. | | East Wallabi I. | | | | |
| Oxalidaceae |||||||
| Oxalis corniculata | Yellow Wood Sorrel | East Wallabi I., West Wallabi I. | | | Naturalised | |
| Papilionaceae |||||||
| Bossiaea spinescens | | East Wallabi I. | | | | |
| Medicago polymorpha | Burr Medic | Little Pigeon I., Pigeon I. | Little Rat I., Rat I., Suomi I. | Pelsaert I. | Naturalised | |
| Medicago sp. | | | Rat I. | | Naturalised | |
| Melilotus indicus | | Beacon I., North I. | Bushby I., Little Rat I., Rat I. | Basile I., Gun I., Pelsaert I., Post Office I. | Naturalised | |
| Mirbelia ramulosa | | East Wallabi I. | | | | |
| Phormiaceae |||||||
| Dianella revoluta | Blueberry Lily | "Eagle Point Islet", East Wallabi I., Oystercatcher I., Pigeon I., Seagull I., Tattler I., West Wallabi I. | | | | |
| Pittosporaceae |||||||
| Pittosporum phillyreoides | Weeping Pittosporum | 10 islands | | Middle I. | | |
| Plantaginaceae |||||||
| Plantago coronopus | Buckshorn Plantain | | Little Rat I. | | | |
| Plantago debilis | | East Wallabi I., North I., Pigeon I., West Wallabi I. | | Middle I. | | |
| Plumbaginaceae |||||||
| Muellerolimon salicorniaceum | | 10 islands | Little Rat I., Rat I. | Middle I. | | |
| Poaceae |||||||
| Austrodanthonia caespitosa | | East Wallabi I., North I. | | | | |
| Austrostipa crinita | | North I. | | | | |
| Austrostipa elegantissima | | East Wallabi I., Long I., Oystercatcher I., Pigeon I., Seagull I., Turnstone I., West Wallabi I. | | Middle I. | | |
| Austrostipa flavescens | | Akerstrom I., Oystercatcher I., Seagull I., Tattler I. | | | | |
| Austrostipa variabilis | | East Wallabi I., North I., Tattler I., West Wallabi I. | Rat I. | | | |
| Avena barbata | Bearded Oat | Little Pigeon I., Pigeon I. | Roma I., Wooded I. | Basile I., Pelsaert I. | Naturalised | |
| Avena fatua | Wild Oat | North I. | Alexander I., Little Rat I., Rat I., Serventy I., Suomi I., Wooded I. | Basile I., Burnett Rock, Burton I., Pelsaert I., Uncle Margie I. | Naturalised | |
| Avena sp. | | Beacon I., Tattler I. | Bushby I. | | Naturalised | |
| Bromus arenarius | Sand Brome | 13 islands | 13 islands | Burnett Rock, Burton I., Coronation I. Newman I., Pelsaert I., Post Office I., Stick I. | | |
| Bromus diandrus | Great Brome | Beacon I., Little Pigeon I., Long I., North I., Pigeon I., Seagull I., Turnstone I. | Alexander I., Campbell I., Gilbert I., Leo I., Wooded I. | Basile I., Burton I., Eight I., Three I. | Naturalised | |
| Bromus hordeaceus | Soft Brome | 11 islands | | Middle I., Pelsaert I., Square I. | Naturalised | |
| Bromus japonicus var. vestitus | | Seal I. | | | Naturalised | |
| Bromus madritensis | Madrid Brome | North I. | | | Naturalised | |
| Bromus rubens | Red Brome | | | Basile I., Burnett Rock, Uncle Margie I. | Naturalised | |
| Bromus sp. | | | Campbell I. | Gun I., Murray I., One I., Sweet I. | Naturalised | |
| Cynodon dactylon | Couch | East Wallabi I., North I., Pigeon I. | Rat I., Wooded I. | | Naturalised | |
| Cynodon sp. | | | Rat I. | | | |
| Ehrharta brevifolia | Annual Veldt Grass | East Wallabi I. | | Pelsaert I. | Naturalised | |
| Ehrharta longiflora | Annual Veldt Grass | Barge Rock, Beacon I., Little Pigeon I., Pigeon I., Seagull I., Tattler I. | 12 islands | Basile Rock, Burton I., Eight I., Gun I., Jackson I., Newman I., Pelsaert I., Uncle Margie I. | Naturalised | |
| Eragrostis dielsii | Mallee Lovegrass | Akerstrom I., East Wallabi I., Little Pigeon I., North I., Pigeon I., Turnstone I. | Little Rat I., Rat I. | Pelsaert I. | | |
| Hordeum murinum subsp. leporinum | Barley Grass | Little Pigeon I., North I., Pigeon I. | Alexander Island | Basile I. | Naturalised; in Western Australia this is treated at species rank as Hordeum leporinum. | |
| Lachnagrostis filiformis | Blown Grass | East Wallabi I., West Wallabi I. | | | Harvey et al. (2001) lists this as Agrostis avenacea, but this is now a synonym of L. filiformis. | |
| Lolium multiflorum | Italian Ryegrass | West Wallabi I. | | | Naturalised | |
| Lolium perenne | Perennial Ryegrass | West Wallabi I. | | Basile I. | Naturalised | |
| Lolium rigidum | Wimmera Ryegrass | Alcatraz I., Little Pigeon I. | | Pelsaert I. | Naturalised | |
| Lolium temulentum | Drake | | Campbell I., Leo I., Rat I. | Stick I. | Naturalised | |
| Parapholis incurva | Coast Barbgrass | North I. | Bynoe I., Campbell I., Keru I., Leo I., Morley I., Roma I. | Uncle Margie I. | Naturalised | |
| Pennisetum clandestinum | Kikuyu Grass | | Little Rat I. | | Naturalised | |
| Phalaris canariensis | Canary Grass | | | Post Office I. | Naturalised | |
| Phalaris minor | Lesser Canary Grass | North I., Pigeon I., East Wallabi I. | Alexander I., Morley I., Serventy I., Suomi I. | Basile I., Burnett Rock, Burton I., Post Office I., Uncle Margie I. | Naturalised | |
| Phleum pratense | Timothy | | | "Gun Islet" | Naturalised | |
| Poa annua | Winter Grass | Beacon I., East Wallabi I. | | | Naturalised | |
| Poa poiformis | Coastal Poa | East Wallabi I. | | | | |
| Polypogon monspeliensis | Annual Beardgrass | Little Pigeon I., Long I., West Wallabi I. | | | Naturalised | |
| Polypogon tenellus | | East Wallabi I., Pigeon I., West Wallabi I. | | | | |
| Rostraria cristata | | Little Pigeon I., North I., Pigeon I. | Bynoe I., Serventy I. | | Naturalised | |
| Setaria dielsii | Diels' Pigeon Grass | 16 islands | 11 islands | Burnett Rock, Burton I., Gun I., Middle I., Newman I., Pelsaert I., Square I., Three I. | | |
| Setaria sp. | | Dick I. | | | | |
| Spinifex longifolius | Beach Spinifex | 15 islands | 13 islands | Burton I., Coronation I., Hummock I., Middle I., Pelsaert I., Post Office I., Stick I., Uncle Margie I. | | |
| Sporobolus virginicus | Marine Couch | North I., Oystercatcher I., Pigeon I., Seagull I., Turnstone I., West Wallabi I. | | Middle I. | | |
| Triticum aestivum | Wheat | North I. | | | Naturalised | |
| Vulpia myuros | Rat's Tail Fescue | Akerstrom I., East Wallabi I., Little Pigeon I., North I., Pigeon I., Turnstone I., West Wallabi I. | Little Rat I., Rat I., Serventy I. | | Naturalised | |
| Polygonaceae |||||||
| Emex australis | Doublegee | Little Pigeon I., Pigeon I. | Rat I. | | Naturalised | |
| Portulacaceae |||||||
| Calandrinia calyptrata | Pink Purslane | North I. | | Rotondella I., Uncle Margie I. | | |
| Primulaceae |||||||
| Anagallis arvensis | Pimpernel | Pigeon I., West Wallabi I. | Alexander I., Bushby I., Little Rat I., Rat I., Serventy I. | Gun I., Middle I., Pelsaert I. | Naturalised | |
| Proteaceae |||||||
| Grevillea argyrophylla | Silvery-leaved Grevillea | East Wallabi I., North I., Pelican I., Saville-Kent I., West Wallabi I. | | Basile I., Middle I., Murray I. | | |
| Ranunculaceae |||||||
| Ranunculus sessiliflorus | Smallflower Buttercup | East Wallabi I. | | | | |
| Rhamnaceae |||||||
| Spyridium globulosum | Basket Bush | East Wallabi I., North I., West Wallabi I. | | | | |
| Rubiaceae |||||||
| Galium sp. | | East Wallabi I. | | | Harvey et al. (2001) list this as "Galium migrans" but, according to FloraBase, that species is not present in Western Australia. | |
| Opercularia vaginata | Dog Weed | East Wallabi I. | | | | |
| Rutaceae |||||||
| Diplolaena grandiflora | Wild Rose | "Eagle Point Islet", East Wallabi I., Little Pigeon I., Oystercatcher I., Pigeon I., Seagull I., Tattler I., Turnstone I., West Wallabi I. | Little Rat I., Rat I. | Gun I. | | |
| Santalaceae |||||||
| Exocarpos aphyllus | Leafless Ballart | East Wallabi I., Little Pigeon I., Long I., Oystercatcher I., Pigeon I., Seagull I., Tattler I., West Wallabi I. | | | | |
| Exocarpos sparteus | Broom Ballart | North I., West Wallabi I. | | | | |
| Sapindaceae |||||||
| Dodonaea aptera | Coast Hop-bush | East Wallabi I., North I., Oystercatcher I., West Wallabi I. | | | | |
| Dodonaea inaequifolia | | East Wallabi I., Oystercatcher I., West Wallabi I. | | | | |
| Dodonaea viscosa | Sticky Hopbush | Seagull I. | | | | |
| Scrophulariaceae |||||||
| Dischisma arenarium | | West Wallabi I. | | | Naturalised | |
| Solanaceae |||||||
| Lycium ferocissimum | African Boxthorn | | Wooded I. | Arthur I., Davis I., Eight I., Gun I., Pelsaert I., Seven I., Sid Liddon I., Sweet I., Three I. | Naturalised. This has been declared a noxious weed, and an eradication program is in place. Harvey et al. (2001) record the plant on only these ten islands, but in 2007 the Department of Environment and Conservation reported that it had been eradicated from 14 out of 18 islands on which it had previously occurred. | |
| Lycopersicon esculentum | Tomato | | Rat I., Roma I. | Jackson I., Middle I. | Naturalised | |
| Nicotiana glauca | Tree Tobacco | Pigeon I. | | | Naturalised | |
| Nicotiana occidentalis subsp. hesperis | Native Tobacco | 14 islands | Alexander I., Morley I., White I., Wooded I. | Middle I., Pelsaert I. | | |
| Solanum laciniatum | Kangaroo Apple | East Wallabi I. | | | Naturalised | |
| Solanum nigrum | Black Berry Nightshade | Beacon I., East Wallabi I., Little Pigeon I., Pigeon I., West Wallabi I. | Bushby I., Little Rat I., Rat I., Roma I. | Eight I., Gun I. | Naturalised | |
| Solanum symonii | | Alcatraz I., Beacon I., East Wallabi I., Oystercatcher I., Seagull I. | | | | |
| Sterculiaceae |||||||
| Lasiopetalum angustifolium | Narrow Leaved Lasiopetalum | East Wallabi I. | | | | |
| Tamaricaceae |||||||
| Tamarix aphylla | Athel Tree | Pigeon I., West Wallabi I. | | | Naturalised. Harvey et al. (2001) list this as "Tamarix sp.", but T. aphylla is the only Tamarix species naturalised in Western Australia. | |
| Thymelaeaceae |||||||
| Pimelea microcephala | Shrubby Riceflower | 11 islands | | | | |
| Urticaceae |||||||
| Parietaria cardiostegia | | Dakin I., Saville-Kent I. | Bynoe I., Keru I. | Burton I. | | |
| Parietaria debilis | Pellitory | Beacon I., Dakin I., Dick I., Eastern I., East Wallabi I., Long I., North I., Saville-Kent I., West Wallabi I. | Alexander I., Bynoe I., Keru I., Leo I., Little North I., Morley I., Rat I., White I. | 13 islands | | |
| Urtica urens | Small Nettle | East Wallabi I., West Wallabi I. | | | Naturalised | |
| Zygophyllaceae |||||||
| Nitraria billardierei | Nitre Bush | 43 islands | 30 islands | 34 islands | This is the most widespread plant species in the Houtman Abrolhos. | |
| Zygophyllum simile | | Beacon I., Dakin I., Dick I., East Wallabi I., Long I., North I., Saville-Kent I., West Wallabi I. | | | | |