Plant Assessment Form

Tetragonia tetragonioides

Synonyms: Tetragonia tetragonoides, Demidovia tetragonoides Pall. (basionym), Tetragonia expansa Murray

Common Names: New Zealand spinach; warrigal greens

Evaluated on: 5/18/11

List committee review date:

Re-evaluation date:


Elizabeth Brusati, Science Program Manager
1442-A Walnut St. #462, Berkeley, CA 94709
Joseph M. DiTomaso, Specialist in Cooperative Extension
Dept. of Plant Sciences, University of California-Davis
Mail Stop 4, One Shields Ave., Davis CA 95616

No list committee members listed

General Comments

No general comments for this species

Table 2. Criteria, Section, and Overall Scores

Overall Score? Limited
Alert Status? No Alert
Documentation? 2 out of 5
Score Documentation
1.1 ?Impact on abiotic ecosystem processes U. Unknown No Information
Four-part score UCUD Total Score
1.2 ?Impact on plant community C. Minor Observational
1.3 ?Impact on higher trophic levels U. Unknown No Information
1.4 ?Impact on genetic integrity D. None Reviewed Scientific Publication
2.1 ?Role of anthropogenic and natural disturbance in establishment B. Moderate Observational
Total Points
7 Total Score C
2.2 ?Local rate of spread with no management C. Stable Observational
2.3 ?Recent trend in total area infested within state C. Stable Observational
2.4 ?Innate reproductive potential
(see Worksheet A)
U. Unknown Other Published Material
2.5 ?Potential for human-caused dispersal C. Low Other Published Material
2.6 ? Potential for natural long-distance dispersal C. Rare Observational
2.7 ?Other regions invaded C. Already invaded Other Published Material
3.1 ?Ecological amplitude/Range
(see Worksheet C)
B. Moderate Observational
Total Score C
3.2 ?Distribution/Peak frequency
(see Worksheet C)
D. Very low Observational

Table 3. Documentation

Scores are explained in the "Criteria for Categorizing Invasive Non-Native Plants that Threaten Wildlands".

Section 1: Impact
Question 1.1 Impact on abiotic ecosystem processes? U No Information
Identify ecosystem processes impacted:

Sources of information:

No information

Question 1.2 Impact on plant community composition,
structure, and interactions?
C Observational
Identify type of impact or alteration:

Level of impacts in California uncertain.
I have found it to be somewhat abundant in the SF area and on Tomales Bay. Where it occurs, it can become abundant and I imagine likely has impacts. It is easily removed and seems to stay away once removed. (Dan Gluesenkamp, Audubon Canyon Ranch, email 2008). In marshes, it can displace Frankenia salina, and pickleweed (Salicornia spp).
In Hawaii, has been seen overgrowing other vegetation. (HEAR 2010)

Sources of information:

Email from Dan Gluesenkamp, HEAR 2010
Leia Giambastiani, pers. comm.

Question 1.3 Impact on higher trophic levels? U No Information
Identify type of impact or alteration:

No information on impacts to trophic levels. Described as edible greens in Australia and sold in stores as an edible plant.

Sources of information:

No information

Question 1.4 Impact on genetic integrity? D Reviewed Scientific Publication

None. No native Tetragonia in California.

Sources of information:

Hickman, J. C. (ed.) 1993. The Jepson Manual, Higher Plants of California. University of California Press. Berkeley, CA enter text here

Section 2: Invasiveness
Question 2.1 Role of anthropogenic and natural disturbance
in establishment?
C Observational
Describe role of disturbance:

Common on human-made levees disturbed by tidal events.

Sources of information:

Leia Giambastiani, pers. comm.

Question 2.2 Local rate of spread with no management? C Observational
Describe rate of spread:

Appears to be spreading, but his may be in local areas and not statewide.

Sources of information:

Leia Giambastiani, pers. comm.
Joseph M. DiTomaso, personal observation

Question 2.3 Recent trend in total area infested within state? C Observational
Describe trend:

Plant has been in California for a long time and appears to be fairly stable in its spread and distribution.

Sources of information:

Joseph M. DiTomaso, personal observation

Question 2.4 Innate reproductive potential? U Other Published Material
Describe key reproductive characteristics:

Sources of information:

Ahmed and Johnson 2000, Prakash 1967

Question 2.5 Potential for human-caused dispersal? C Other Published Material
Identify dispersal mechanisms:

Horticultural plant, has been researched as a possible vegetable crop in the San Joaquin Valley because it tolerates salinity. Is not widely sold and thus has limited opportunity for long distance human dispersal.

Sources of information:

Ahmed and Johnson 2000, Wilson et al. 2000

Question 2.6 Potential for natural long-distance dispersal? C Observational
Identify dispersal mechanisms:

Little opportunity for natural long-distance dispersal, unless it's washed away by the tides.

Sources of information:

Email from Dan Gluesenkamp, HEAR 2010

Question 2.7 Other regions invaded? C Other Published Material
Identify other regions:

Native to New Zealand. Naturalized in Australia (but also called native there, Ahmed and Johnson 2000), Japan, Europe, Mexico, Argentina, Chile (USDA GRIN 2011)
Naturalized in Denmark, England, the Azores.
In US, naturalized in CA, CT, FL, GA, HI, MA, NC, ND, NY, OH, PA, WA, WI, WV, USA+: (PR)

Sources of information:

Ahmed and Johnson 2000, HEAR 2011, Prakash 1967, USDA-GRIN 2011, USDA NRCS 2011

Section 3: Distribution
Question 3.1 Ecological amplitude/Range? B Observational

Specimens collected from coastal counties from San Diego to Mendocino (Consortium of California Herbaria)
San Pablo National Wildlife Refuge and surrounding areas. Habitat type: along levees on the San Pablo Bay with salt spray and tidal influence. Sunny open areas. Salt Marsh and Salt Marsh Transition zone between upland and marsh.
We've seen (and attempted to remove) it in several sites in both the freshwater and brackish intertidal zones at Abbott's Lagoon (Pt Reyes National Seashore) and also rather surprisingly in a dune restoration site about 15 meters elevation above the beach at our B Ranch site (also Pt. Reyes). (Mark Langan, email 2008)
There generally is a good deal of it in the Half Moon Bay area, particularly on the bluffs adjoining Francis Beach. (Jean Ouellette, email 2008)
The Don Edwards refuge has it, as do the Farallones. (Erik Grijalva, Invasive Spartina Project, email 2008)
At Lands End on GGNRA on edges of Monterey cypress/coastal scrub habitat on sandy soils (Loran May, email 2008)
New Zealand Spinach is common in the coastal State Parks in Malibu, although not really actively spreading. (Michael O_—ÈBrien, email 2008)

Sources of information:

Emails from CalWeedTalk, specimen records from Consortium of California Herbaria
Leia Giambastiani, pers. comm.

Question 3.2 Distribution/Peak frequency? D Observational
Describe distribution:

Seems to be fairly widespread along the coast but only in certain regions, based on emails and records in Calflora

Sources of information:

Emails from CalWeedTalk, specimen records from Consortium of California Herbaria

Worksheet A - Innate reproductive potential

Reaches reproductive maturity in 2 years or less Yes
Dense infestations produce >1,000 viable seed per square meter No
Populations of this species produce seeds every year. Yes
Seed production sustained over 3 or more months within a population annually Unknown
Seeds remain viable in soil for three or more years Unknown
Viable seed produced with both self-pollination and cross-pollination Unknown
Has quickly spreading vegetative structures (rhizomes, roots, etc.) that may root at nodes No
Fragments easily and fragments can become established elsewhere No
Resprouts readily when cut, grazed, or burned No
Total points: 2
Total unknowns: 3
Total score: U?

Related traits:

Worksheet B - Arizona Ecological Types is not included here

Worksheet C - California Ecological Types

(sensu Holland 1986)
Major Ecological Types Minor Ecological Types Code?
Marine Systemsmarine systems
Freshwater and Estuarine lakes, ponds, reservoirs
Aquatic Systemsrivers, streams, canals
estuariesD, < 5%
DunescoastalD, < 5%
Scrub and Chaparralcoastal bluff scrubD, < 5%
coastal scrub
Sonoran desert scrub
Mojavean desert scrub (incl. Joshua tree woodland)
Great Basin scrub
chenopod scrub
montane dwarf scrub
Upper Sonoran subshrub scrub
Grasslands, Vernal Pools, Meadows, and other Herb Communitiescoastal prairie
valley and foothill grassland
Great Basin grassland
vernal pool
meadow and seep
alkali playa
pebble plain
Bog and Marshbog and fen
marsh and swamp
Riparian and Bottomland habitatriparian forest
riparian woodland
riparian scrub (incl.desert washes)
Woodlandcismontane woodland
piñon and juniper woodland
Sonoran thorn woodland
Forestbroadleaved upland forest
North Coast coniferous forest
closed cone coniferous forest
lower montane coniferous forest
upper montane coniferous forest
subalpine coniferous forest
Alpine Habitatsalpine boulder and rock field
alpine dwarf scrub
Amplitude (breadth): B
Distribution (highest score): D

Infested Jepson Regions

Click here for a map of Jepson regions

  • Central West
  • Northwest
  • Southwest