Table S1: Inventory of the introduced plants of Madagascar. “Introduced plants" are here defined as non-native plants presumably introduced by humans (directly or indirectly). Codes explained at end of table. Tropicos Madcat categorization (*'cultivated' usually comes from Perrier's Family notes to genus or binomial name Alien/ Known (following Genus / species (Tropicos family; not species [if blank not in Perrier's native invasive Note / comment for publication (e.g. Tropicos) or best we can determine) entry) Perrier] category status status Source issue with identification and classification) Acanthaceae indigenous non- Asystasia Juss. Asystasia gangetica T. And. endemic gangetica T. And. 4 X- P, T Acanthaceae indigenous non- Barleria prionitis Juss. Barleria prionitis L. endemic L. 3 X- P, T Acanthaceae Brachystephanus africanus In Tropicos MadCat status unsure: Juss. S. Moore possible naturalised X T 'naturalized or indigenous or introduced?' We indicate as 'N', for most sources indicate this plant as native to Asia, and Tropicos MadCat herbaria specimens include one in protected area and one on Ile Ste. Marie. Acanthaceae indigenous non- Justicia Unclear on what basis Tropicos MadCat Juss. Justicia gendarussa L. endemic gendarussa L 1 N P, T designates as indigenous. Acanthaceae indigenous non- Nelsonia Juss. Nelsonia canescens Nees. endemic canescens Nees. 4 X- P, T Confusion on Tropicos (general vs. MadCat) on whether synonym is T. convulvifolia (which is endemic). In any case T. fragrans Acanthaceae is from Asia and widely cultivated and Juss. Thunbergia fragrans Roxb. endemic N D* naturalised according to ARS-GRIN Acanthaceae Thunbergia grandiflora Thunbergia Juss. Roxb. not listed grandiflora Roxb. 2 N P Acanthaceae Thunbergia mysorensis Juss. (Wight) T. Anderson not listed C JT Aceraceae Juss. Acer negundo L. not listed C S Chose 'N' for our category due to Binggeli reference (over Decary); Samyn cites Agave rigida as spontaneous (but this name is Agavaceae ambiguous according to ARS-GRIN). Binggeli Dumort. Agave sisalana Perrine not listed N inv. B*, D, Sa cites as invasive. Synonym from Illustrated handbook of Agavaceae succulent plants: Monocotyledons by Urs Dumort. Agave vivipara L. not listed Agave ixtli Kaw. 2 N inv. P, B Eggli, p73. Binggeli cites as invasive. Tropicos MadCat: "Probably more widespread Aizoaceae Tetragonia tetragonoides that the single known specimen would Martinov (Pall.) Kuntze naturalised N T, D suggest" Aizoaceae Trianthema Martinov Trianthema monogyna L. not listed monogyna 3 N P Altingiaceae Lindl. Liquidambar styraciflua L. not listed C S, CK Amaranthaceae Achyranthe Juss. Achyranthes aspera L. naturalised aspera L. 5 N inv. P, T, D, H Invasive: H; pers. obs. JT Amaranthaceae indigenous non- Aerva javanica Juss. Aerva javanica Juss. endemic Juss. 3 X- P, T Amaranthaceae indigenous non- Aerva lanata (L.) Juss. Aerva lanata (L.) Juss. endemic Juss. 3 X- P, T Amaranthaceae Alternanthera littoralis P. Juss. Beauv. naturalised N T We've designated as 'N' for most sources consider this plant native to Asia and it is a common cultivar; Tropicos MadCat specimen sites include two protected areas as well as Amaranthaceae Alternanthera sessilis (L.) indigenous non- Alternanthera urban garden. Unclear on what basis Juss. R. Br. ex DC. endemic sessilis R. Br. 3 N P, T, D, S a Tropicos MadCat designated as indigenous. Note that Tropicos MadCat has inconsistent treatment of A. viridis L. which it considers synonym of A. blitum subsp. emarginatus (which it designates as indig non endem) but A. blitum is designated naturalised. GRIN Amaranthaceae Amaranthus accepts A. viridis L. and has a synonym with Juss. Amaranthus blitum L. naturalised viridis Moq 3 N P, T Moq. as author. Amaranthaceae Amaranthus dubius Mart. Juss. ex Thell. naturalised N T Amaranthus Amaranthaceae Amaranthus hypochondriacus Juss. hypochondriacus L. not listed L. 3 N P Amaranthaceae Amaranthus Juss. Amaranthus spinosus L. naturalised spinosus L. 3 N inv. P, T, D Invasive: pers. obs. JT A. tristis L. is "not in project" Tropicos MadCat, but A. tristis Wild. is synonym A. Amaranthaceae Amaranthus tricolor L. GRIN has no A. tristis. Assume Juss. Amaranthus tricolor L. naturalised tristis L. 3 N P, T, D that Perrier had wrong authority. Amaranthaceae Juss. Celosia argentea L. naturalised N T Amaranthaceae Juss. Celosia trigyna L. naturalised Celosia trignya L. 4 4 N P, T, D Amaranthaceae Centrostachys aquatica (R. Juss. Br.) Wall. naturalised N T Amaranthaceae Chenopodium Juss. Chenopodium album L. naturalised album L. 3 N P, T, D Amaranthaceae Chenopodium ambrosioides Chenopodium Juss. L. naturalised ambrosioides L. 3 N P, T, D Chenopodium Amaranthaceae Chenopodium giganteum amaranticolor Juss. D. Don naturalised Cost & Reyn 3 N P, T, D Amaranthaceae Chenopodium Juss. Chenopodium murale L. naturalised murale L. 3 N P, T, D Amaranthaceae indigenous non- Cyathula Juss. Cyathula cylindrica Moq. endemic cylindrica Moq. 5 X- P, T Amaranthaceae Cyathula prostrata (L.) Cyathula Juss. Blume naturalised prostrata Blume 5 N P, T Amaranthaceae Cyathula uncinulata Juss. (Schrad.) Schinz naturalised N T Amaranthaceae Digera arvensis Juss. Digera muricata Mart. naturalised Forsk 4 N P*, T Amaranthaceae Juss. Spinacia oleracea L. not listed C Boiteau Amaryllidaceae J. St.-Hil. Allium cepa L. not listed Allium cepa L. 1 C P, D Amaryllidaceae J. Allium St.-Hil. Allium escalonicum L. not listed escalonicum L. 1 C P, D Amaryllidaceae J. Allium sativum St.-Hil. Allium sativum Linn not listed Linn 1 C P, D Amaryllidaceae J. St.-Hil. Furcraea foetida (L.) Haw. naturalised N T Amaryllidaceae J. Fourcroya St.-Hil. Furcraea gigantea Vent not listed gigantea Vent 2 N P, D, S a Anacardiaceae R. Anacardium P*, C, D, Br. Anacardium occidentale L. not listed occidentale L 5 N M Tropicos MadCat: "This sp is endemic to NW Madagascar. It was planted by the Water and Forestry Department at forestry stations and elsewhere along the E coast, where it has Anacardiaceae R. now become naturalized. Its presence in Br. Gluta tourtour Marchand endemic E T Toliara Prov. requires confirmation" Anacardiaceae R. Br. Juglans nigra L. not listed C G Anacardiaceae R. Br. Juglans regia L. not listed C F Anacardiaceae R. Mangifera indica Br. Mangifera indica L. not listed L 5 N P*, D, M Anacardiaceae R. Schinus terebinthifolia Br. Raddi not listed N inv. JT, Sa Invasive: pers. obs. JT Sclerocarya birrea (A. Anacardiaceae R. Rich.) Hochst. subsp. caffra Br. (Sond.) Kokwaro not listed C F, D Anacardiaceae R. Searsia pentaphylla (Jacq.) Br. F. A . B a r k l e y not listed C S Anacardiaceae R. Spondias dulcis Sol. ex Spondias dulcis Br. Parkinson not listed Forsk 1 C P, F, D, M Anacardiaceae R. Br. Spondias mombin L. not listed N Inv. F, M Invasive at Ivoloina according to M Anacardiaceae R. Toxicodendron Br. succedaneum (L.) Kuntze not listed C S Annonaceae Juss Annona cherimola Mill. not listed C M Annonaceae Juss Annona glabra L. not listed C F, M Annonaceae Juss Annona mucosa Jacq. not listed C F, M Annonaceae Juss Annona muricata L. not listed C F, M Anona reticulata Annonaceae Juss Annona reticulata L. not listed L. 5 N P, D, M Anona senegalensis Annonaceae Juss Annona senegalensis Pers. naturalised Poiret. 5 N P, T, D Anona squamosa Annonaceae Juss Annona squamosa L. not listed L. 5 N P, D, M Cananga odorata (Lam.) Annonaceae Juss Hook.f. & Thomson not listed Cananga odorata 1 C P, D Monodora myristica Annonaceae Juss (Gaertn.) Dunal not listed C S Apiaceae Lindl. Centella asiatica (L.) Urb. naturalised N inv. T, S a , H invasive: H Known to naturalize widely elsewhere (ARS- Apiaceae Lindl. Daucus carota L. not listed C CK GRIN) Tropicos MadCat: 'widely cultivated and Apocynaceae probably more widely naturalized than the Juss. Allamanda cathartica L. naturalised N T single record would suggest' Apocynaceae indigenous non- Aselepias Juss. Asclepias curassavica L. endemic curassavica L 5 X- P, T Apocynaceae Calotropis procera (Aiton) indigenous non- Calotropis Juss. W.T. Aiton endemic procera R.Br 2 X+ P, T, D Apocynaceae Catharanthus pusillus Juss. (Murray) G. Don naturalised N T Perrier surprisingly considered the rosy periwinkle introduced. P. Phillipson notes (pers. comm. 2010): This species "is essentially native to a quite restricted area in SE Madagascar, but is widely distributed throughout as a weed – probably from re- Apocynaceae Catharanthus roseus (L.) introduced cultivated material". Invasive Juss. G. Don Endemic Vinca rosea L. 3 I&I inv. P, T, S a , H behaviour: H Apocynaceae Funtumia elastica (P. Juss. Preuss) Stapf not listed C S Apocynaceae Gomphocarpus fruticosus Gomphocarpus Juss. (L.) W.T. Aiton naturalised fruticosus R Br 5 N P, T, D, S a Apocynaceae Gymnema sylvestre (Retz.) Juss. R. Br. ex Schult. naturalised N T Apocynaceae Holarrhena pubescens Wall. Juss. ex G. Don not listed C G Apocynaceae Juss. Microloma incanum Decne. naturalised N T Apocynaceae Juss. Nerium oleander L. not listed C G Apocynaceae Juss. Plumeria rubra L. naturalised Plumeria rubra L. 1 N P, T Tropicos MadCat: "the introduced Asian sp T. cordata has been grown in Madagascar as an Apocynaceae Telosma cordata (Burm.f.) ornamental, but it is not known whether it Juss. Merr. cultivated C T has persisted" No species listed is marked as naturalized in Apocynaceae Tylophora R. Br. un-named Tropicos MadCat, but one naturalized on Juss. species naturalised N T accepted tally at genus level Apocynaceae Juss. Wrightia pubescens R. Br. not listed C S Alocasia macrorrhizos (L.) Colocasia indica Araceae Juss. G. Don not listed Sum. 1 C P*, D Colocasia Colocasia esculenta (L.) antiquorum Araceae Juss. Schott naturalised Schott. 2 N P*, T, D Araucariaceae Henkel & W. Agathis dammara (Lamb.) Hochstetter Rich. not listed C S Araucariaceae Henkel & W. Agathis robusta (C. Moore Hochstetter ex F. Muell.) F. M. Bailey not listed C S Araucariaceae Henkel & W. Araucaria angustifolia Hochstetter (Bertol.) Kuntze not listed C S Araucariaceae Henkel & W.