Tetragonia tetragonioides
(New Zealand spinach)

Pictures

Picture	Title	Caption	Copyright
Title Habit Caption Tetragonia tetragonioides (New Zealand spinach); habit. Mokuauia, Oahu, Hawaii, USA. February, 2005. Copyright ©Forest Starr & Kim Starr - CC BY 4.0	Habit	Tetragonia tetragonioides (New Zealand spinach); habit. Mokuauia, Oahu, Hawaii, USA. February, 2005.	©Forest Starr & Kim Starr - CC BY 4.0
Title Habit Caption Tetragonia tetragonioides (New Zealand spinach); habit. Kanaha Beach, Maui, Hawaii, USA. March, 2004. Copyright ©Forest Starr & Kim Starr - CC BY 4.0	Habit	Tetragonia tetragonioides (New Zealand spinach); habit. Kanaha Beach, Maui, Hawaii, USA. March, 2004.	©Forest Starr & Kim Starr - CC BY 4.0
Title Habit and leaves Caption Tetragonia tetragonioides (New Zealand spinach); habit and leaves. Mokuauia, Oahu, Hawaii, USA. February, 2005. Copyright ©Forest Starr & Kim Starr - CC BY 4.0	Habit and leaves	Tetragonia tetragonioides (New Zealand spinach); habit and leaves. Mokuauia, Oahu, Hawaii, USA. February, 2005.	©Forest Starr & Kim Starr - CC BY 4.0
Title Flowers and leaves Caption Tetragonia tetragonioides (New Zealand spinach); flowers and leaves. Keanae, Maui, Hawaii, USA. July, 2009. Copyright ©Forest Starr & Kim Starr - CC BY 4.0	Flowers and leaves	Tetragonia tetragonioides (New Zealand spinach); flowers and leaves. Keanae, Maui, Hawaii, USA. July, 2009.	©Forest Starr & Kim Starr - CC BY 4.0
Title Flower Caption Tetragonia tetragonioides (New Zealand spinach); close-up of single flower. Kanaha Beach, Maui, Hawaii, USA. March, 2004. Copyright ©Forest Starr & Kim Starr - CC BY 4.0	Flower	Tetragonia tetragonioides (New Zealand spinach); close-up of single flower. Kanaha Beach, Maui, Hawaii, USA. March, 2004.	©Forest Starr & Kim Starr - CC BY 4.0

Identity

Preferred Scientific Name

• Tetragonia tetragonioides (Pall.) Kuntze

Preferred Common Name

• New Zealand spinach

Other Scientific Names

• Demidovia tatragonioides Pallas, Enum. Hort. Demidof 150, t. 1. 1781.
• Tatragonia cornuta Gaertner, Fruct. Sem. Pl. 2: 483. 1791.
• Tetragonia expansa Murray, Commentat. Soc. Regiae Sci. Gott. 6: 13. 1783
• Tetragonia expansa THUNB. ex MURR.
• Tetragonia halimifolia G. Foster, Fl. Ins. Austr. 39. 1786.
• Tetragonia inermis 1852. F. Mueller, Linnaea 25: 384.
• Tetragonia japonica Thunberg, Fl. Jap. 208. 1784.
• Tetragonia quadricornis Stokes, Bot. Mat. Med. 3: 127. 1812, nom. illegit.
• Tetragonia tetragonoides

International Common Names

• English: New Zealand spinach; perpetual spinach; sea spinach
• Spanish: espinaca de Nueva Zelandia; Espinacia de Nueva Zelandica; spinaca Nuevo Zelandia
• French: epinard; Epinard de la Nouvelle-Zelande; tetragon; tetragone; tetragone cornue
• Chinese: xin xi lan bo cai; yeung poh tsoi
• Portuguese: espinafre de Nova Zelandia

Local Common Names

• : Novozelandskii shipinat; tetragonia shpinatnaia
• : summer spinach
• Australia: Botany Bay greens; Sydney greens; warrigal cabbage; warrigal cabbage; warrigal greens; warrigal spinach
• Brazil: espinafre da Nova Zelandia
• Croatia: Novozealandski shpinat
• Denmark: Newzealandsk spinat
• Germany: Neuseelaender Spinat; Neuseelandischer spinat
• Greece: spanaki Neas Zilandias
• Hungary: Ujzelandi paraj
• Italy: spinacio della Nouva Zelanda; Spinacio della Nouva-Zelande
• Japan: tsuruna; Tsuruna
• Netherlands: Nieuwzeelandse spinazie; Niewzeelandse Spinazie
• New Zealand: kokihi; paraihia; rengamutu; rengarenga; tutae-ika-moana
• Norway: Ny-Zealandsk spinat
• Philippines: baguio spinach
• Poland: szpinak Nowozelandzki
• Serbia: Novozelandski spanac(h)
• Slovenia: Novozelandska schpinacha
• South Africa: Nu Zeeland spinasie
• Sweden: Ny-seelaendisk spenat; Nyzeelandsk spenat
• Switzerland: neuseelander-spinat

EPPO code

• TEATE (Tetragonia tetragonioides)

Summary of Invasiveness

T. tetragonioides is a leafy herb native to the Far East, parts of Australia, New Zealand and some Pacific Islands. It has been introduced to Africa, the Americas, Europe and parts of Asia. It is considered invasive in coastal habitats in Chile, Hawaii, Florida and California, and is one of several principal invaders in Reunion. The strongest case for its invasiveness is made in California, where it is controlled in natural areas. T. tetragonioides establishes in and competes with coastal, beach, dune, cliff and salt marsh vegetation. It is naturalized mainly in frost free coastal climates but it persists after cultivation in cold climates, such as in northern USA and Europe.

Taxonomic Tree

• Domain: Eukaryota
•     Kingdom: Plantae
•         Phylum: Spermatophyta
•             Subphylum: Angiospermae
•                 Class: Dicotyledonae
•                     Order: Caryophyllales
•                         Family: Aizoaceae
•                             Genus: Tetragonia
•                                 Species: Tetragonia tetragonioides

Notes on Taxonomy and Nomenclature

A variety of latin binomials have been used for the New Zealand spinach Tetragonia tetragonioides (currently accepted). The most frequent synonym in the literature is Tetragonia expansa, and there may be as much literature referring to the latter as to the former.

Description

From Vivrette (2004):

Stems: mat-forming, spreading to 30-140 cm. Leaves: 10-100 by 50-50 mm; petiole 10-30 mm, winged; blade pale green abaxially, dark green adaxially, midvein and lateral veins raised abaxially, ovate-rhombic to triangular, base truncate, papillate with larger papillae abaxially. Inflorescences: peduncle to 2 mm. Flowers: sometimes unisexual; calyx lobes spreading, yellow, ovate to half orbiculate, 2 mm; stamens clustered or scattered. Fruits: turbinate, 8-12 mm; horns 4-6. Seeds: smooth.

From Morris and Duretto (2009):

Annual or perennial herb, decumbent or ascending; stems to 1 m long. Leaves broadly hastate, rhomboid or lanceolate; petiole 10–45 mm long, papillose, decurrent; blade 10–80(–100?) mm long, 5–50 mm wide, dark green above, paler below with larger papillae. Flowers axillary, solitary or rarely 2 together, 8–10 mm diam.; pedicels to 5 mm long. Calyx lobes 4–5, 1 or 2 of them ovate-semiorbicular, larger than the rest, the smaller lobes ovate-triangular to lanceolate, obtuse or acute; adaxial surface yellowish, minutely papillose; abaxial surface green, papillose. Stamens 8–16, in groups alternating with the calyx lobes. Stigmas 3–8(–10?) in 2 groups, equal in number to the loculi. Fruit indehiscent, at first green, becoming dry and bony, to 13 mm long and 12 mm wide, globular or turbinate variously ridged at the summit; ridges produced into short equal or unequal horns. Seeds in 2 rows, c. 2.5 mm long, pyriform. Flowering and fruiting throughout year.

Plant Type

Distribution

T. tetragonioides has been introduced to Africa, the Americas, Europe, Indonesia, Iran, Israel and the Philippines. It is widespread in Europe. Its seeds have been on sale in London since 1835 or earlier, and it was recorded in unlikely places such as Switzerland fairly early on after its initial introduction to Europe (Déséglise, 1881). Its popularity as an easy-to-grow spinach alternative means its introduced range is most likely larger than indicated in the distribution table. 

There are disagreements over its native range. It seems that most agree that it is native from the Far East south to Australia (e.g. Harris, 1998; Hara et al., 2008; Morris and Duretto, 2009). Most accounts now regard it as non-native and naturalized in South America, including Chile (Reiche and Philippi, 1898; Zuloaga and Morrone, 1996; Ugarte et al., 2011; Missouri Botanical Garden, 2013; Zappi, 2014). However, older accounts still hold some influence in the literature, and its nativity in Chile and Argentina is still frequently claimed (Sturtevant, 1919; Roskruge, 2011). Occasionally the plant is claimed as native to Africa (e.g. Ugarte et al., 2011), but probably more because of the prevalence of the genus and the family in South Africa than due to a knowledge of the phylogeography of the species itself. In Australia, T. tetragonioides has established in New South Wales and Tasmania, the two states it is not native to (Randall, 2007).

Distribution Table

The distribution in this summary table is based on all the information available. When several references are cited, they may give conflicting information on the status. Further details may be available for individual references in the Distribution Table Details section which can be selected by going to Generate Report.

History of Introduction and Spread

T. tetragonioides is regarded as native in from China and Korea to Japan, Australia and New Zealand (Allan et al., 1961; Ohwi, 1965; Kim, 2005; Morris and Duretto, 2009; eFloras, 2013). It is probably native in other sites in between these countries as it can spread naturally via ocean currents (Abe, 2006). However, this ability to spread by ocean currents is shared by others in the genus, which could potentially lead to an overestimation of its native range.

It was collected in South America in 1847 (Ugarte et al., 2011); by some accounts, T. tetragonioides may be native in South America (Morong and Britton, 1893; Sturtevant, 1919; Roskruge, 2011), but now most authors now class it as a cultivated, adventive or naturalized plant there (Macbride and Dahlgren, 1937; Zuloaga and Morrone, 1996; Ugarte et al., 2011; Zappi, 2014).

T. tetragonioides was reported by Captain Cook and eaten by his crew in 1770. Joseph Banks is credited with giving seeds to Kew Botanic Gardens, UK, in 1772, and by 1824 it was on sale in London. It then probably spread throughout Europe rather quickly (Sturtevant, 1919). Wild populations were established in France in the 1920s (Tempére, 1920).

T. tetragonioides was on sale in New York in seed catalogues in 1828 after initially being spread by members of a horticultural society (Sturtevant, 1919; Roskruge, 2011). It was recorded wild in California in 1891 and Hawaii in 1909. It was already known in South America by the mid to late 1800s (Morong and Britton, 1893; Reiche and Philippi, 1898; Sturtevant, 1919; Ugarte et al., 2011).

The timing of the spread is harder to pinpoint in Africa, but it is clearly widely planted there (Grubben, 2004). Its suitability as a vegetable in coastal habitats means that it has been introduced to many oceanic islands for human consumption (PIER, 2014). By all accounts the plant is probably more widely distributed than is documented here. 

Introductions

Risk of Introduction

T. tetragonioides is most likely to be introduced to new sites by gardeners wishing to grow it, and its seeds are available via internet and catalogue mail-order. The seeds are easily transported and remain viable for long periods in storage. Spread from one river flood plain or coastal site to another is also possible since the seeds are known to disperse via fresh and salt water currents (Abe, 2006; Nicol et al., 2009); though not strictly a halophyte, T. tetragonioides is reasonably salt tolerant (Roskruge, 2011).

Habitat

T. tetragonioides is generally associated with coastal habitats in its native and introduced invasive range. It grows well on dunes, beaches, salt marshes, coastal cliffs and other coastal locations (Abe, 2006; Robbins, 1940; Roskruge, 2011). It is naturalized mainly in frost free coastal climates but it persists after cultivation in cold climates, such as in northern USA and Europe. It may also persist unassisted in abandoned gardens, or spread slowly from any place it is planted.

Habitat List

Biology and Ecology

Genetics

Chromosome number 2n = 32

Reproductive biology

T. tetragonioides is predominantly self-pollinated but cross-pollination may occur (Grubben, 2004). The fruits fall to the ground on ripening so it can reseed itself. Germination can be irregular but generally takes less than 20 days, and may occur naturally in spring in either temperate or cold climates (Roskruge, 2011). Under cultivation plants reached harvestable size 50-55 days after planting (Roskruge, 2011).

Physiology and phenology

Germination takes up to 20 days and first flowers 59-63 days after planting. Late maturing plants can produce an abundance of seeds (Roskruge, 2011).

Associations

T. tetragonioides is associated with coastal plants such as beach morning glory, Ipomoea imperati.

Environmental requirements

T. tetragonioides prefers mesic conditions but there is evidence that it is drought tolerant (Hara et al., 2008). It grows well on dunes, beaches, salt marshes and other coastal locations (Abe, 2006; Robbins, 1940; Roskruge, 2011). Plants are reasonably salt-tolerant, though seedlings may not withstand as much salt as mature plants. T. tetragonioides is also tolerant of a variety of soil types, preferring pH 5.8-7.5 (Roskruge, 2011). It is reported to prefer frost-free sites (Grubben, 2004; Roskruge, 2011), although it may encounter frost in parts of its native range, and can persist after cultivation in much colder sites (such as Wisconsin, Connecticut, Oregon and Washington, USA, and Suffolk, UK), suggesting that as long as it can flower and fruit in a single growing season, the seeds will not be killed by freezing temperatures.

Climate

Soil Tolerances

Soil reaction

• acid
• neutral

Soil texture

• light
• medium

Special soil tolerances

• infertile
• saline
• shallow

Natural enemies

Notes on Natural Enemies

None of the pests in the Natural Enemies table are described as serious pests of T. tetragonioides (Roskruge, 2011). Some of the natural enemies can carry pathogens of potatoes; specifically, Helminthosporium sp. is commonly known as silver scurf in potatoes, and Verticillium alboatrum is a wilt disease found on potatoes (APHIS, 2004; Roskruge, 2011).

Means of Movement and Dispersal

Natural dispersal (non-biotic)

The floating horned seeds of T. tetragonioides can be transported by water, including rivers and oceans (Abe, 2006; Nicol et al., 2009). Plants have established on a recently formed volcanic island in the Pacific Ocean, near Japan, apparently from seed transported naturally on ocean currents (Abe, 2006).

Vector transmission (biotic)

T. tetragonioides has not been associated with animal dispersal in the literature, but transport of plants for bird nesting materials could be possible, as could ingestion by tortoises.

Accidental introduction

Plants have been dispersed in bird seed in Britain (Hanson and Mason, 1985).

Intentional introduction

This plant has been deliberately introduced around the world as an easy-to-grow spinach alternative (Sturtevant, 1919; Cambie and Ferguson, 2003; Roskruge, 2011).

Pathway Causes

Pathway Vectors

Plant Trade

Impact Summary

Economic Impact

There are no reports of T. tetragonioides impacting crops. Costs of control in terms of labour and herbicide costs are not recorded. It is grown as a crop in Israel, and as a common garden plant around the world (APHIS, 2004; Grubben, 2004; Roskruge, 2011).

Environmental Impact

Impact on habitats

T. tetragonioides is known to establish significant populations in coastal habitats outside of its native range, including dunes, salt marshes and coastal cliffs in Hawaii, Florida, California and Reunion (Robbins, 1940; Starr and Starr, 2006; Zomlefer et al., 2007; Soubeyran, 2008).

Impact on biodiversity

The spread of T. tetragonioides outside of its native range in coastal habitats is not associated with many accounts of its negative impacts on individual species. The spreading habit (almost vine-like) and abundant fleshy leaves of T. tetragonioides give it significant competitive ability. It competes with common native plants like Ipomoea imperati on white sand beaches in Hawaii (Rick Warshauer USGS-Biological Resources Division, Kilauea, Hawaii). It is one of several dominant species in Korean dunes (Kim, 2005).

Social Impact

T. tetragonioides is a common garden plant around the world and has potential medicinal applications (Okuyama and Yamazaki, 1983; Cambie and Ferguson, 2003; APHIS, 2004; Grubben, 2004; Roskruge, 2011).

Risk and Impact Factors

• Invasive in its native range
• Proved invasive outside its native range
• Has a broad native range
• Abundant in its native range
• Is a habitat generalist
• Pioneering in disturbed areas
• Fast growing
• Has high reproductive potential
• Has propagules that can remain viable for more than one year
• Reproduces asexually

• Ecosystem change/ habitat alteration
• Modification of successional patterns
• Monoculture formation
• Threat to/ loss of native species

• Competition - monopolizing resources
• Competition - shading
• Competition - smothering
• Competition - strangling
• Pest and disease transmission
• Interaction with other invasive species
• Rapid growth

• Highly likely to be transported internationally accidentally
• Highly likely to be transported internationally deliberately
• Highly likely to be transported internationally illegally
• Difficult to identify/detect as a commodity contaminant

Uses

Economic value

T. tetragonoides is rarely cultivated as a crop for sale in large quantities, though it appears to have been imported into the United States from Israel for sale (APHIS, 2004), and may occasionally be sold in markets in Africa (Grubben, 2004). It is cultivated worldwide by gardeners as an easy to grow leafy green.

Social benefit

The fresh shoots of T. tetragonoides can be eaten raw, but leaves are generally cooked. 100 grams of T. tetragonoides is 94 g water, protein 1.5 g, fat 0.2 g, carbohydrate 2.5 g, Ca 58 mg, P 28 mg, Fe 0.8 mg, vitamin A 4400 IU, thiamin 0.04 mg, riboflavin 0.13 mg, niacin 0.5 mg, folate 15 µg and ascorbic acid 30 mg; it provides 59 kJ or 14 calories (Grubben, 2004). However, much of the calcium is present as oxalates and not available to the human body. Eating it raw has been discouraged because of the high saponin content (Grubben, 2004).

Uses List

Environmental

• Wildlife habitat

General

• Sociocultural value

Human food and beverage

• Vegetable

Medicinal, pharmaceutical

• Traditional/folklore

Detection and Inspection

A number of floras describe T. tetragonioides (Allan et al., 1961; Ohwi, 1965; Morris and Duretto, 2009; eFloras, 2013). It has been described in a dichotomous key for agricultural seeds available in German and translated into English (Brouwen and Stahlin, 1980).The distinctive horned 4-chambered seeds could be relatively easy to spot for someone familiar with the species.

Similarities to Other Species/Conditions

The climbing New Zealand spinach, Tetragoniatrigyna Banks and Sol. ex Hook.f., has smaller leaves and stems than T. tetragonioides (Roskruge, 2011).

Prevention and Control

Rapid response

Small populations have been controlled manually on Midway and Farrolon Islands, in the Northwest Hawaiian Islands (Forest Starr, pers. comm. Starr Environmental, Maui Hawaii, 2013)

Public awareness

T. tetragonioides is included in some websites documenting invasive species, such as PIER (2014).

Physical/mechanical control

Plants can be pulled up, although the effectiveness of this has not been reported.

Chemical control

Control with glyphosate may be effective based on other plants in Aizoaceae (DiTomaso, 2013).

Control by utilization

Not likely to be effective considering that growers of T. tetragonioides are most likely to harvest leaves and shoots for food rather than pulling whole plants.

Ecosystem restoration

Removal of T. tetragonioides coupled with planting of desirable plants and shrubs may prevent it establishing in the seedbank.

Gaps in Knowledge/Research Needs

The natural and human mediated spread of T. tetragonioides is not well documented: it was claimed as native in South America by some authors but it appears that botanists in South America now regard it as non-native. Genetic sequencing of wild populations and cultivated plants throughout its range could give insights into the spread of the plant. The claim that the plants in Europe were sourced via seeds that were brought back to England by Sir Joseph Banks could be investigated.

References

Abe T, 2006. Colonization of Nishino-shima Island by plants and arthropods 31 years after eruption. Pacific Science, 60(3):355-365. http://www.uhpress.hawaii.edu/journals

Acevedo-Rodríguez P, Strong MT, 2012. Catalogue of Seed Plants of the West Indies. Washington, D.C., USA: Smithsonian Institution Scholarly Press, 1192 pp. [Smithsonian Contributions to Botany 98.]

Allan HH, 1961. Flora of New Zealand, I. Indigenous Tracheophyta. Wellington, New Zealand: Government Printer.

Alonso Paz EA, Bassagoda MJ, 2003. Survey of the flora and plant communities of Cerro Verde, Rocha, Uruguay. (Relevamiento de la flora y comunidades vegetales del Cerro Verde, Rocha, Uruguay.) Comunicaciones Botánicas, 127:1-20.

APHIS, 2004. Importation of New Zealand Spinach (Tetragonia tetragonioides) Palas. from Israel into the United States (A Qualitative, Pathway-initiated Risk Assessment). United States Department of Agriculture.

Arévalo JR, Delgado JD, Otto R, Naranjo A, Salas M, Fernández-Palacios JM, 2005. Distribution of alien vs. native plant species in roadside communities along an altitudinal gradient in Tenerife and Gran Canaria (Canary Islands). Perspectives in Plant Ecology, Evolution and Systematics, 7(3):185-202. http://www.sciencedirect.com/science/journal/14338319

Barker S, 1970. Quondong Station, South Australia: a field context for applied rangeland research. Transactions of the Royal Society of South Australia, 94:179-190.

Brouwer W, Stahlin A, 1955. The seed handbook (Handbuch der Samenkunde). Frankfurt/ Main; DLG-Verlags-GmbH, 664 pp.

Bullock DJ, North SG, Dulloo ME, Thorsen M, 2003. The impact of rabbit and goat eradication on the ecology of Round Island, Mauritius. In: Turning the tide: the eradication of invasive species: Proceedings of the International Conference on eradication of island invasives [ed. by Veitch, C. R.\Clout, M. N.]. Gland, Switzerland: IUCN-The World Conservation Union, 53-63.

Cambie RC, Ferguson LR, 2003. Potential functional foods in the traditional Maori diet. Mutation Research, Fundamental and Molecular Mechanisms of Mutagenesis, 523/524:109-117.

Campos JA, Herrera M, 2010. Analysis of the allochthonous flora of Bizkaia (Basque Country, Spain. (Análisis de la flora alóctona de Bizkaia (País Vasco, España).) Lazaroa, 30:7-33.

Coyne P, 2010. Ecological rebound on Phillip Island, South Pacific. Ecological Management & Restoration, 11(1):4-15. http://www.blackwell-synergy.com/loi/emr

Cronk Q, 1983. Tetragonia tetragonoides (Pall.) Kuntze (Herbarium specimen). Royal Botanic Garden Edinburgh, Edinburgh. Edinburgh, UK: Royal Botanic Garden Edinburgh.

Déséglise A, 1881. Florula genevensis advena.

DiTomaso JM, Kyser GB, Oneto SR, Wilson RG, Orloff SB, Anderson LW, Wright SD, Roncoroni JA, Miller TL, Prather TS, Ransom C, Beck KG, Duncan C, Wilson KA, Mann JJ, 2013. Weed Control in Natural Areas in the Western United States. Davis, California, USA: Weed Research and Information Center, University of California, 544 pp.

Downey PO, Scanlon TJ, Hosking JR, 2010. Prioritizing weed species based on their threat and ability to impact on biodiversity: a case study from New South Wales. Plant Protection Quarterly, 25(3):111-126.

eFloras, 2013. Flora of China. St. Louis, Missouri and Cambridge, Massachusetts, USA: Missouri Botanical Garden and Harvard University Herbaria. http://www.efloras.org/flora_page.aspx?flora_id=2

GBIF, 2013. Global Biodiversity Information Facility. Global Biodiversity Information Facility (GBIF). http://data.gbif.org/species/

Grubben GJH, Denton OA, 2004. Plant resources of tropical Africa 2. Vegetables [ed. by Grubben, G. J. H.\Denton, O. A.]. Wageningen, Netherlands: PROTA Foundation, 667 pp.

Guézou A, Pozo P, Buddenhagen C, 2007. Preventing establishment: an inventory of introduced plants in Puerto Villamil, Isabela Island, Galapagos. PLos One, No.October:e1042. http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0001042

Guézou A, Trueman M, Buddenhagen CE, Chamorro S, Mireya Guerrero A, Pozo P, Atkinson R, 2010. An extensive alien plant inventory from the inhabited areas of Galapagos. PLoS ONE, No.April:e10276. http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0010276

Halvorson WL, 1992. Alien Plants at Channel Islands National Park. Alien Plant Invasions in Native Ecosystems of Hawaii: Management and Research. Honolulu, Hawaii, USA: University of Hawaii Cooperative National Park Resources Studies Unit, 64-96.

Hanson CG, Mason JL, 1985. Bird seed aliens in Britain. Watsonia, 15:237-252.

Hara M, Tokunaga K, Kuboi T, 2008. Isolation of a drought-responsive alkaline a-galactosidase gene from New Zealand spinach. Plant Biotechnology, 25:497-501.

Harris G, 1998. Invasive New Zealand weeds: our native plant invaders. CalEPPC News, 6:8-9.

Harris MR, Facelli JM, 2003. Competition and resource availability in an annual plant community dominated by an invasive species, Carrichtera annua (L. Aschers.), in South Australia. Plant Ecology, 167(1):19-29.

Herbst DR, Wagner WL, 1992. Alien plants on the northwestern Hawaiian Islands. Alien plant invasions in native ecosystems of Hawaii: management and research. Honolulu, Hawaii, USA: University of Hawaii Cooperative National Park Resources Studies Unit, 189-224.

Hosseini S, Habibi MK, Mosahebi G, Motamedi M, Winter S, 2012. First report on the occurrence of Tobacco streak virus in sunflower in Iran. Journal of Plant Pathology, 94(3):585-589. http://sipav.org/main/jpp/index.php/jpp/issue/view/124

Imada CT, 2012. Hawaiian Native and Naturalized Vascular Plants Checklist. Bishop Musem Technical Report. Honolulu, Hawaii, USA: Bishop Museum.

Kartesz JT, 2013. The biota of North America program (BONAP). North American Plant Atlas.

Kim KD, 2005. Invasive plants on disturbed Korean sand dunes. Estuarine, Coastal & Shelf Science, 62(1/2):353-364. http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6WDV-4DSW9XS-1&_user=3891418&_handle=V-WA-A-W-BA-MsSAYWA-UUW-U-AABBEBDVBV-AABACAYWBV-VCZZVDCCW-BA-U&_fmt=full&_coverDate=01%2F01%2F2005&_rdoc=28&_orig=browse&_srch=%23toc%236776%232005%23999379998%23535048!&_cdi=6776&view=c&_acct=C000028398&_version=1&_urlVersion=0&_userid=3891418&md5=675e53cfb2dcabd57f017ce8f3e95677

Kress WJ, Lace JH, Farr E, Daw Yin YK, 2003. A checklist of the trees, shrubs, herbs, and climbers of Myanmar. Washington, DC, USA: Department of Systematic Biology, Botany, National Museum of Natural History.

Macbride JF, 1937. Flora of Peru [ed. by Dahlgren, B. E.]. Chicago, USA: Field Museum of Natural History.

Meyer J-Y, 2009. Strategic Action Plan to Fight Against Invasive Introduced Plantes in Rapa Nui (Easter Island). (Plan de Accion Estratégico para Luchar Contra las Plantes Introducidas Invasoras en Rapa Nui (Isla De Pascua).) Ministry of Education, Higher Education and Research, Government of French Polynesia.

Missouri Botanical Garden, 2013. Tropicos database. St Louis, USA: Missouri Botanical Garden. http://www.tropicos.org/

Morong T, Britton NL, 1893. II - An Enumeration of the Plants Collected by Dr. Thomas Morong in Paraguay, 1888-1890. Annals of the New York Academy of Sciences, 7:45-280.

Morris DI, 2009. 101 Aizoacea. Flora of Tasmania [ed. by Duretto, M. F.]. Hobart, Australia: Tasmanian Herbarium, Tasmanian Museum and Art Gallery, 10. http://demo1.tmag.tas.gov.au/

Nicol J, Weedon J, Marsland K, 2009. Understorey vegetation monitoring of the Chowilla river red gum watering sites. South Australian Research and Development Institute (Aquatic Sciences). Adelaide, Australia: South Australian Research and Development Institute (Aquatic Sciences), 76 pp.

Ohwi J, 1965. Flora of Japan. Washington, DC, USA: Smithsonian Institute.

Okuyama E, Yamazaki M, 1983. The principles of Tetragonia tetragonoides having anti-ulcerogenic activity. II. Isolation and structure of cerebrosides. Chemical and Pharmaceutical Bulletin Japan, 31:2209-2219.

PIER, 2014. Pacific Islands Ecosystems at Risk. Honolulu, USA: HEAR, University of Hawaii. http://www.hear.org/pier/index.html

Randall RP, 2007. The introduced flora of Australia and its weed status [ed. by Randall RP]. Glen Osmond, Australia: CRC for Australian Weed Management, iv + 524 pp.

Reiche C, Philippi F, 1898. Flora of Chile (Flora de Chile). Santiago de Chile, Chile: Imprenta Cervantes.

Robbins W, 1940. Alien plants growing without cultivation in California, 637:128 pp.

Roskruge N, 2011. The commercialisation of ko¯kihi or New Zealand spinach (Tetragonia tetragonioides) in New Zealand. Agronomy New Zealand [Proceedings of the 41st Agronomy Society of New Zealand Conference, Gisborne, New Zealand, 8-10 November 2011.], 41:149-156. http://www.agronomysociety.org.nz/2011-journal-papers.html

Soubeyran Y, 2008. Exotic species invading French overseas communities. Inventory of fixtures and recommendations. (Les espèces exotiques envahissantes dans les collectivités françaises d'outre-mer. Etat des lieux et recommandations.) Exotic species invading French overseas communities. French committee of the IUCN.

Starr F, Starr K, 2006. Oahu Offshore Islets Botanical Survey. Hawaii State Department of Land and Natural Resources and Offshore Islet Restoration Committee.

Sturtevant EL, 1919. State of New York-Department of Agriculture 27th Annual Report. New York, USA: JB Lyon Company, State Printers.

Tempére MG, 1920. Notes on some new and interesting plants of the Arcachonnaise region. (Notes sur quelques plantes nouvelles ou intéressantes de la région Arcachonnaise.) Actes de la Société Linnéenne De Bordeaux:27-28.

Ugarte E, Lira F, Fuentes N, Klotz S, 2011. Vascular alien flora, Chile. Check List, 7(3):365-382 pp.

USDA-ARS, 2013. Germplasm Resources Information Network (GRIN). Online Database. Beltsville, Maryland, USA: National Germplasm Resources Laboratory. https://npgsweb.ars-grin.gov/gringlobal/taxon/taxonomysearch.aspx

USDA-ARS, 2014. Germplasm Resources Information Network (GRIN). Online Database. Beltsville, Maryland, USA: National Germplasm Resources Laboratory. https://npgsweb.ars-grin.gov/gringlobal/taxon/taxonomysearch.aspx

Vivrette NJ, 2004. Tetragonia (L.). In: Flora of North America: Magnoliophyta: Caryophyllidae, Part 1. Oxford University Press, 77 pp.

Weakley AS, 2012. Flora of the Southern and Mid-Atlantic States. Chapel Hill, North Carolina, USA: University of North Carolina, 1072 pp. URL: http://www.herbarium.unc.edu/flora.htm [Accessed 04 September 2013]

Welbaum, G. E., 2015. Vegetable production and practices., Vegetable production and practices:ix + 476 pp.

Wester L, 1992. Origin and distribution of adventive alien flowering plants in Hawaii. Honolulu, HI, USA: University of Hawaii, pp. In: Alien plant invasions in native ecosystems of Hawaii: management and research [ed. by Stone, C. P. \Smith, C. W. \Tunison, J. T.]. Honolulu, HI, USA: University of Hawaii, 99-154.

Wisflora, 2014. Wisflora: Checklist of the Vascular Plants of Wisconsin. Madison, Winsconsin, USA: Wisconsin State Herbarium, University of Wisconsin. http://www.botany.wisc.edu/wisflora/

Wishner C, 1998. Flora of the Santa Monica Mountains: synonymized checklist and index. Crossosoma, 23:3.

Wunderlin RP, Hansen BF, 2014. Atlas of Florida Vascular Plants. http://florida.plantatlas.usf.edu/

Zappi D, 2014. Aizoaceae. (Aizoaceae in Lista de Espécies da Flora do Brasil.) List of Species in the Flora of Brazil. Rio de Janeiro, Brazil: Botanical Garden of Rio de Janeiro.

Zomlefer WB, Giannasi DE, Judd WS, 2007. A floristic survey of National Park Service areas of Timucuan Ecological and Historic Preserve (including Fort Caroline National Memorial), Duval County, Florida. Journal of the Botanical Research Institute of Texas:1157-1178.

Zuloaga FO, Morrone O, 1996. I. Pteridophyta, Gymnosperamae and Angiospermae (Monocotyledoneae). (Catálogo de las Plantas Vasculares de la República Argentina I. Pteridophyta, Gymnosperamae y Angiospermae (Monocotyledoneae).) Catalogue of Vascular Plants of the Argentine Republic.

Contributors

17/03/14 Original text by:

Christopher Buddenhagen, Florida State University, USA

Distribution Maps