# Endemic flora of the Chatham Islands

Although over 650 km (400 mi) from the main islands, the flora of the Chatham Islands is largely similar to the rest of New Zealand. About 400 of the 875 taxa (including hybrids) attested in the Chatham Islands are indigenous to them; of these, only 47 are endemic to the islands. The endemic plants of the islands are divided between taxa related to those on the North Island and those with stronger links to the South Island and the subantarctic islands of New Zealand. The flora of the Chatham Islands were described from samples in the mid-1800s by botanists Joseph Hooker and Ferdinand von Mueller, neither of whom ever visited the islands, while Leonard Cockayne provided the first comprehensive Chatham Islands Flora in the early 1900s. The islands have become highly noted for their flora and fauna, attracting ecotourists. One endemic, the Chatham Islands forget-me-not (Myosotidium hortensia), has become a botanical symbol of the islands due to its widespread cultivation in and outside New Zealand.
The Chatham archipelago comprises 40 islands and rocks. In addition to the larger islands of Chatham and Pitt Island, both endemic and introduced plants are found on various smaller islets. Coastal forests on the islands are dominated by indigenous and endemic trees such as Olearia traversiorum and Coprosma chatamica, with trees such as Dracophyllum arboreum further inland. In the wettest areas on the islands grow swamp forests of Coprosma propinqua and Olearia telmatica. Shore plants have a higher portion of naturalized species, often to the detriment of endemic flora. Although many of the endemic taxa are threatened from naturalized flora and grazing by livestock, the populations of many species have rebounded since the 1980s due to widespread environmental regeneration practices. However, many taxa continue to be at risk, including three taxa listed as Nationally Critical by the New Zealand Threat Classification System (NZTCS).

## Vascular plants

Endemic vascular plants of the Chatham Islands :
| Scientific name | Common name(s) | Family | NZTCS | Distribution |
| Aciphylla dieffenbachii (F.Muell.) Kirk, 1899 | Dieffenbach's speargrass, soft speargrass, coxella | Apiaceae | Declining | Chatham, Pitt, Mangere, South East, small islets |
| Aciphylla traversii (F.Muell.) Hook.f., 1867 | Chatham Island speargrass, taramea karupuru | Apiaceae | Declining | Chatham, Pitt |
| Asplenium chathamense Brownsey, 1985 | Chatham Island spleenwort | Aspleniaceae | Naturally Uncommon | Chatham, Pitt, Mangere, South East, small islets |
| Astelia chathamica (Skottsb.) L.B.Moore, 1966 | Chatham Islands kakaha, Moriori flax | Asteliaceae | Declining | Chatham, Pitt |
| Austroderia turbaria (Connor) N.P.Barker & H.P.Linder, 2010 | Chatham Island toetoe | Poaceae | Nationally Critical | Chatham, Pitt |
| Brachyglottis huntii (F. Muell.) B.Nord., 1978 | Chatham Island Christmas tree, rautini | Asteraceae | Nationally Vulnerable | Chatham, Pitt |
| Callitriche chathamensis (R.Mason) Lansdown, 2022 | Chatham Island starwort | Plantaginaceae | Naturally Uncommon | Chatham, Pitt |
| Carex chathamica Petrie, 1915 | Chatham sedge | Cyperaceae | Naturally Uncommon | Chatham, Pitt, South East |
| Carex ventosa C.B.Clarke, 1906 | Chatham Islands forest sedge | Cyperaceae | Naturally Uncommon | Chatham, Pitt, Mangere, South East, small islets |
| Coprosma chathamica Cockayne, 1901 | Chatham Island karamū | Rubiaceae | Naturally Uncommon | Chatham, Pitt, South East |
| Copromosa propinqua var. martini W.R.B.Oliv., 1935 | Tāpātāpā | Rubiaceae | Naturally Uncommon | Chatham, Pitt, South East |
| Corokia macrocarpa Kirk, 1899 | Hokotaka, whakataka | Argophyllaceae | Naturally uncommon | Chatham, Pitt, Mangere, South East |
| Disphyma papillatum Chinnock, 1971 | Chatham Island ice plant | Aizoaceae | Naturally uncommon | Chatham, Pitt, Mangere, South East, small islets |
| Dracophyllum arboreum Cockayne, 1901 | Chatham Island grass tree, tarahinau | Ericaceae | Naturally Uncommon | Chatham, Pitt, South East |
| Festuca coxii (Petrie) Hack., 1906 | Cox's fescue | Poaceae | Naturally Uncommon | Chatham, Pitt, Mangere, South East, small islets |
| Geranium traversii Hook.f., 1867 | Chatham Island geranium | Geraniaceae | Naturally Uncommon | Chatham, Pitt, Mangere, South East, small islets |
| Gentianella chathamica subsp. chathamica (Cheeseman) T.N.Ho & S.W.Liu, 1993 | Chatham Island gentian | Gentianaceae | Naturally Uncommon | Chatham, Pitt |
| Leptecophylla robusta (Hook.f.) C.M.Weiller, 1999 | Pouteretere | Ericaceae | Naturally Uncommon | Chatham, Pitt |
| Leptinella featherstonii F.Muell., 1864 | Chatham Island button daisy, mutton bird plant | Asteraceae | Naturally Uncommon | Chatham, Pitt, Mangere, South East, small islets |
| Linum monogynum var. chathamicum Cockayne, 1902 | Chatham Island linen flax | Linaceae | Nationally Critical | Chatham, Pitt, Mangere, South East |
| Macrolearia chathamica (Kirk) Saldivia, 2022 | Keketerehe | Asteraceae | Declining | Chatham, Pitt, Mangere, South East, Little Mangere |
| Macrolearia semidentata (Decne. ex Hook.) Saldivia, 2022 | Hangatere, Chatham Island aster, swamp aster | Asteraceae | Declining | (Chatham Islands) |
| Melicytus chathamicus (F.Muell.) Garn.-Jones, 1987 | Inihina, hakina, hinahina, Chatham Island mahoe | Violaceae | Naturally Uncommon | Chatham, Pitt, Mangere, South East, small islets |
| Myosotidium hortensia (Decne.) Baill., 1890 | Kopakopa, Chatham Island forget-me-not, kopukapuka | Boraginaceae | Declining | Chatham, Pitt, Mangere, South East, small islets |
| Myoporum semotum Heenan & de Lange, 2011 | Chatham Islands myoporum | Scrophulariaceae | Declining | Chatham, Pitt, Mangere, South East |
| Myrsine coxii Cockayne, 1902 | Swamp matipo, swamp mapou, Cox's matipo | Primulaceae | Declining | Chatham, Pitt, South East |
| Olearia telmatica Heenan & de Lange, 2008 | Shell akeake, swamp akeake | Asteraceae | Declining | Chatham, Pitt, South East |
| Olearia traversiorum (F.Muell.) Hook.f., 1867 | Hakapiri, Chatham Island akeake | Asteraceae | Declining | Chatham, Pitt, South East, Mangere, small islets |
| Plagianthus regius subsp. chathamicus (Cockayne) de Lange, 2008 | Chatham Island ribbonwood | Malvaceae | Declining | Chatham, Pitt, South East, Mangere, Little Mangere |
| Poa chathamica Petrie, 1902 | Chatham Islands poa | Poaceae | Naturally Uncommon | Chatham, Pitt, South East, Mangere, small islets |
| Pseudopanax chathamicus Kirk, 1899 | Hoho, Chatham Island lancewood | Araliaceae | Naturally Uncommon | (Chatham Islands) |
| Pterostylis silvicultrix (F.Muell.) D.L.Jones & M.A.Clem., 2002 | Tutukiwi, Chatham Island greenhood | Orchidaceae | Naturally Uncommon | Chatham, Pitt, Mangere (possible) |
| Senecio radiolatus subsp. radiolatus F.Muell., 1864 | | Asteraceae | Naturally Uncommon | (Chatham Islands) |
| Sonchus grandifolius Kirk, 1894 | Pūhā pārākau rahi, embergeria, Chatham Island sow thistle | Asteraceae | Recovering | Chatham, Pitt, Mangere, South East, small islets |
| Sporadanthus traversii (F.Muell.) Buchanan, 1875 | Chatham Island bamboo rush | Restionaceae | Naturally Uncommon | Chatham |
| Veronica barkeri Cockayne, 1899 | Barker's koromiko, Chatham Island tree hebe | Plantaginaceae | Nationally Critical | Chatham, Pitt, South East |
| Veronica chathamica Buchanan, 1875 | Chatham Island koromiko | Plantaginaceae | Naturally Uncommon | Chatham, Pitt, Mangere, South East, small islets |
| Veronica dieffenbachii Benth., 1846 | Dieffenbach's koromiko | Plantaginaceae | Naturally Uncommon | Chatham, Pitt, Mangere, South East |

## Non-vascular plants

Endemic non-vascular flora of the Chatham Islands :
| Scientific name | Family | NZTCS | Distribution |
| Macromitrium longirostre var. ramsayae (Vitt) Fife, 2017 | Orthotrichaceae | Naturally Uncommon | Chatham, Pitt |
| Sarcodia linearis (J.Agardh) Kylin, 1932 | Sarcodiaceae | Data Deficient | (Chatham Islands) |
| Ceramium chathamense G.Feldmann, 1950 | Ceramiaceae | Data Deficient | (Chatham Islands) |
| Durvillaea chathamensis C.H.Hay, 1979 | Durvillaeaceae | Naturally Uncommon | (Chatham Islands) |
| Gigartina grandifida J.Agardh, 1876 | Gigartinaceae | Naturally Uncommon | (Chatham Islands) |
| Lessonia tholiformis C.H.Hay, 1989 | Lessoniaceae | Naturally Uncommon | (Chatham Islands) |
| Landsburgia myricifolia J.Agardh, 1870 | Sargassaceae | Naturally Uncommon | (Chatham Islands) |
| Pyrophyllon cameronii (W.A.Nelson) W.A.Nelson, 2003 | Erythrotrichiaceae | Naturally Uncommon | (Chatham Islands) |