Plant Assessment Form

More Tetragonia tetragonioides resources

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:

Evaluator(s)

Elizabeth Brusati, Science Program Manager
Cal-IPC
1442-A Walnut St. #462, Berkeley, CA 94709
510-843-3902
edbrusati@cal-ipc.org

Joseph M. DiTomaso, Specialist in Cooperative Extension
Dept. of Plant Sciences, University of California-Davis
Mail Stop 4, One Shields Ave., Davis CA 95616
530-754-8715
jmditomaso@ucdavis.edu

No list committee members listed

General Comments

3/21/2025 J. Burger
Removed association with Estuaries under "Aquatic" to stop species from being filtered out as an aquatic 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

Impact?
Four-part score UCUD Total Score
C

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

Invasiveness?
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

Distribution?
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? Consider the impact on the natural range and variation of abiotic ecosystem processes and system-wide parameters in ways that significantly diminish the ability of native species to survive and reproduce. Alterations that determine the types of communities that can exist in a given area are of greatest concern. Examples of abiotic processes include: - fire occurrence, frequency, and intensity; - geomorphological changes such as erosion and sedimentation rates; - hydrological regimes, including soil water table; - nutrient and mineral dynamics, including salinity, alkalinity, and pH; - light availability (e.g. when an aquatic invader covers an entire water body that would otherwise be open). Select the one letter below that best describes this species' most severe impact on an abiotic ecosystem process: A. Severe, possibly irreversible, alteration or disruption of an ecosystem process. B. Moderate alteration of an ecosystem process. C. Minor alteration of an ecosystem process. D. Negligible perceived impact on an ecosystem process. U. Unknown.	U No Information
Identify ecosystem processes impacted: Sources of information: No information
Question 1.2 Impact on plant community composition, structure, and interactions? Consider the cumulative ecological impact of this species to the plant communities it invades. Give more weight to changes in plant composition, structure, and interactions that involve rare or keystone species or rare community types. Examples of severe impacts include: - formation of stands dominated (>75% cover) by the species; - occlusion (>75% cover) of a native canopy, including a water surface, that eliminates or degrades layers below; - significant reduction or extirpation of populations of one or more native species. Examples of impacts usually less than severe include: - reduction in propagule dispersal, seedling recruitment, or survivorship of native species; - creation of a new structural layer, including substantial thatch or litter, without elimination or replacement of a pre-existing layer; - change in density or depth of a structural layer; - change in horizontal distribution patterns or fragmentation of a native community; - creation of a vector or intermediate host of pests or pathogens that infect native plant species. Select the one letter below that best describes this species' impact on community composition, structure and interactions: A. Severe alteration of plant community composition, structure, or interactions. B. Moderate alteration of plant community composition. C. Minor alteration of community composition. D. Negligible impact known; causes no perceivable change in community composition, structure, or interactions. U. Unknown.	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? Consider the cumulative impact of this species on the animals, fungi, microbes, and other organisms in the communities that it invades. Although a non-native species may provide resources for one or a few native species (e.g. by providing food, nesting sites, etc.), the ranking should be based on the species' net impact on all native species. Give more weight to changes in composition and interactions involving rare or keystone species or rare community types. Examples of severe impacts include: - extirpation or endangerment of an existing native species or population; - elimination or significant reduction in native species' nesting or foraging sites, cover, or other critical resources (i.e., native species habitat), including migratory corridors. Examples of impacts that are usually less than severe include: - minor reduction in nesting or foraging sites, cover, etc. for native animals; - minor reduction in habitat connectivity or migratory corridors; - interference with native pollinators; - injurious components, such as awns or spines that damage the mouth and gut of native wildlife species, or production of anti-digestive or acutely toxic chemical that can poison native wildlife species. Select the one letter below that best describes this species' impact on community composition and interactions: A. Severe alteration of higher trophic populations, communities, or interactions. B. Moderate alteration of higher trophic level populations, communities, or interactions. C. Minor alteration of higher trophic level populations, communities or interactions. D. Negligible impact; causes no perceivable change in higher trophic level populations, communities, or interactions. E. Unknown.	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? Consider whether the species can hybridize with and influence the proportion of individuals with non-native genes within populations of native species. Mechanisms and possible outcomes include: - production of fertile or sterile hybrids that can outcompete the native species; - production of sterile hybrids that lower the reproductive output of the native species. Select the one letter below that best describes this species' impact on genetic integrity: A. Severe (high proportion of individuals). B. Moderate (medium proportion of individuals). C. Minor (low proportion of individuals). D. No known hybridization. U. Unknown.	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? Assess this species' dependence on disturbance: both human and natural: for establishment in wildlands. Examples of anthropogenic disturbances include: - grazing, browsing, and rooting by domestic livestock and feral animals; - altered fire regimes, including fire suppression; - cultivation; - silvicultural practices; - altered hydrology due to dams, diversions, irrigation, etc.; - roads and trails; - construction; - nutrient loading from fertilizers, runoff, etc. Examples of natural disturbance include: - wildfire; - floods; - landslides; - windthrow; - native animal activities such as burrowing, grazing, or browsing. Select the first letter in the sequence below that describes the ability of this species to invade wildlands: A. Severe invasive potential: this species can establish independent of any known natural or anthropogenic disturbance. B. Moderate invasive potential: this species may occasionally establish in undisturbed areas but can readily establish in areas with natural disturbances. C. Low invasive potential: this species requires anthropogenic disturbance to establish. D. No perceptible invasive potential: this species does not establish in wildlands (though it may persist from former cultivation). U. Unknown.	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? Assess this species' rate of spread in existing localized infestations where the proportion of available habitat invaded is still small when no management measures are implemented. Select the one letter below that best describes the rate of spread: A. Increases rapidly (doubling in <10 years) B. Increases, but less rapidly C. Stable D. Declining U. Unknown	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? Assess the overall trend in the total area infested by this species statewide. Include current management efforts in this assessment and note them. Select the one letter below that best describes the current trend: A. Increasing rapidly (doubling in total range statewide in <10 years) B. Increasing, but less rapidly C. Stable D. Declining U. Unknown	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? Assess the innate reproductive potential of this species. Worksheet A is provided for computing the score.	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? Assess whether this species is currently spread: or has high potential to be spread: by direct or indirect human activity. Such activity may enable the species to overcome natural barriers to dispersal that would not be crossed otherwise, or it may simply increase the natural dispersal of the species. Possible mechanisms for dispersal include: - commercial sales for use in agriculture, ornamental horticulture, or aquariums; - use as forage, erosion control, or revegetation; - presence as a contaminant (seeds or propagules) in bulk seed, hay, feed, soil, packing materials, etc.; - spread along transportation corridors such as highways, railroads, trails, or canals; - transport on boats or boat trailers. Select the one letter below that best describes human-caused dispersal and spread: A. High: there are numerous opportunities for dispersal to new areas. B. Moderate: human dispersal occurs, but not at a high level. C. Low: human dispersal is infrequent or inefficient. D. Does not occur. U. Unknown.	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? We have chosen 1 km as the threshold of "long-distance." Assess whether this species is frequently spread, or has high potential to be spread, by animals or abiotic mechanisms that can move seed, roots, stems, or other propagules this far. The following are examples of such natural long-distance dispersal mechanisms: - the species' fruit or seed is commonly consumed by birds or other animals that travel long distances; - the species' fruits or seeds are sticky or burred and cling to feathers or hair of animals; - the species has buoyant fruits, seeds, or other propagules that are dispersed by flowing water; - the species has light propagules that promote long-distance wind dispersal; - The species, or parts of it, can detach and disperse seeds as they are blown long distances (e.g., tumbleweed). Select the one letter below that best describes natural long-distance dispersal and spread: A. Frequent long-distance dispersal by animals or abiotic mechanisms. B. Occasional long-distance dispersal by animals or abiotic mechanisms. C. Rare dispersal more than 1 km by animals or abiotic mechanisms. D. No dispersal of more than 1 km by animals or abiotic mechanisms. U. Unknown.	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? Assess whether this species has invaded ecological types in other states or countries outside its native range that are analogous to ecological types not yet invaded in your state (see Worksheets B, C, and D for California, Arizona, and Nevada, respectively, in Part IV for lists of ecological types). This information is useful in predicting the likelihood of further spread within your state. Select the one letter below that best describes the species' invasiveness in other states or countries, outside its native range. A. This species has invaded 3 or more ecological types elsewhere that exist in your state and are as yet not invaded by this species (e.g. it has invaded Mediterranean grasslands, savanna, and maquis in southern Europe, which are analogous to California grasslands, savanna, and chaparral, respectively). B. Invades 1 or 2 ecological types that exist but are not yet invaded in your state. C. Invades elsewhere but only in ecological types that it has already invaded in the state. D. Not known as an escape anywhere else. U. Unknown.	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? Refer to Worksheet C and select the one letter below that indicates the number of different ecological types that this species invades. A. Widespread: the species invades at least three major types or at least six minor types. B. Moderate: the species invades two major types or five minor types. C. Limited: the species invades only one major type and two to four minor types. D. Narrow: the species invades only one minor type. U. Unknown.	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? To assess distribution, record the letter that corresponds to the highest percent infested score entered in Worksheet C for any ecological type.	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? Scoring Criteria for Worksheet A A. High reproductive potential (6 or more points). B. Moderate reproductive potential (4-5 points). C. Low reproductive potential (3 points or less and less than 3 Unknowns). U. Unknown (3 or fewer points and 3 or more Unknowns).

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? A means >50% of type occurrences are invaded; B means 20% to 50%; C means 5% to 20%; D means present but <5%; U means unknown (unable to estimate percentage of occurrences invaded)
Marine Systems	marine systems
Freshwater and Estuarine	lakes, ponds, reservoirs
Aquatic Systems	rivers, streams, canals
Aquatic Systems	estuaries
Dunes	coastal	D, < 5%
	desert
	interior
Scrub and Chaparral	coastal bluff scrub	D, < 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
	chaparral
Grasslands, Vernal Pools, Meadows, and other Herb Communities	coastal prairie
	valley and foothill grassland
	Great Basin grassland
	vernal pool
	meadow and seep
	alkali playa
	pebble plain
Bog and Marsh	bog and fen
Bog and Marsh	marsh and swamp
Riparian and Bottomland habitat	riparian forest
	riparian woodland
	riparian scrub (incl.desert washes)
Woodland	cismontane woodland
	piñon and juniper woodland
	Sonoran thorn woodland
Forest	broadleaved upland forest
	North Coast coniferous forest
	closed cone coniferous forest
	lower montane coniferous forest
	upper montane coniferous forest
	subalpine coniferous forest
Alpine Habitats	alpine boulder and rock field
Alpine Habitats	alpine dwarf scrub
	Amplitude (breadth):	B
	Distribution (highest score):	D

Infested Jepson Regions

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Central West
Northwest
Southwest

California Invasive Plant Council

Protecting California’s environment and economy from invasive plants

Plant Assessment Form

More Tetragonia tetragonioides resources

Tetragonia tetragonioides

Evaluator(s)

General Comments

Table 2. Criteria, Section, and Overall Scores

Table 3. Documentation

Worksheet A - Innate reproductive potential

Related traits:

Worksheet C - California Ecological Types

Infested Jepson Regions