Mexican Pokeweed | Phytolacca heterotepala

California Pest Rating for
Photo by: Robert Sikora
Mexican pokeweed | Phytolacca heterotepala H. Walter
Caryophyllales: Phytolaccaceae
Pest Rating: A  |  Proposed Seed Rating: R



Initiating Event:

Phytolacca heterotepala has been present as a weed in the San Francisco Bay Area since the 1950s. It was recently found for the first time growing in a pasture in San Luis Obispo County (PDR 400P06359971, 400P06359972; Cal Flora 2018) and confirmed as a new county record. Phytolacca heterotepala is currently Q-rated. A permanent pest rating proposal is required to support an official pest rating.

History and Status:

Background: Phytolacca heterotepala was first documented from California in 1915 from a nursery in San Francisco [A. Eastwood s.n. CAS] (Howell 1960). Naturalized populations were documented starting in 1955 for San Francisco County [L. Jones s.n., CAS-BOT-BC434466], in 1959 for Santa Barbara County [E. Blakley 2942, CAS-BOT-BC434440], in 1960 for Santa Clara County [J. H. Thomas 8763 1960, DS577499], in 1974 for Marin County [P. Ellman s.n., CAS652035], and in 2003 for Alameda County [S. Pugh s.n., JEPS103234] (Howell 1960, Munz and Keck 1968, CAS Botany Collection Database 2018, CCH 2018). Except for some San Francisco collections, most of these comprise waits in disturbed areas or gardens.The populations from Santa Clara and Santa Barbara counties are presumed extirpated.

Plants can reach 2.5 m (Jepson eFlora 2018, Nienaber and Thieret 2004). Sepals are greenish, oblong and unequal; the largest sepal is twice as wide as the smallest. The stamens are in two whorls. It has been documented in California establishing from cultivation and in disturbed areas at an elevation up to 100 meters. Flowering starts in summer and continues into the winter months (Jepson Flora).

Phytolacca heterotepala may be mistaken for the more common and widespread Phytolacca americana L, which is introduced in California and native to the eastern United States. Phytolacca heterotepala is similar morphologically to and sometimes treated as a synonym of Phytolacca icosandra L. (red inkplant, tropical pokeweed), which is native to Arizona, Mexico, and northern South America and introduced in California (San Diego County) (CCH 2018, Davis 1985, Rzedowski and Calderón de Rzedowski 2000, Steinmann 1997, Xu et al. 2017). We follow treatments of the genus for California (Howell 1960, Jepson eFlora 2018), North America (Nienaber and Thieret 2004), and phylogenetically (Ali et al. 2015).

Synonyms: Not known.

Worldwide Distribution: Phytolacca heterotepala is native to Mexico and northern South America. In addition to its introduction and establishment in California, this taxon is documented as a newly established (Ortiz 1987) and invasive species in two areas of Portugal (Domingues de Almeida and Freitas 2006, Invasive plants in Portugal, 2016).

Official Control: Phytolacca heterotepala has not been reported as a harmful plant in other states and nations (USDA APHIS PCIT).

California Distribution: Phytolacca heterotepala has been present as a weed in the San Francisco Bay Area since the 1950s, and recently has been found in San Luis Obispo County (Jepson eFlora 2018, CalFlora 2018).

California Interceptions: Phytolacca heterotepala has been intercepted twice by CDFA in 2017 through general surveys in San Luis Obispo County (PDR 400P06359971, 400P06359972; CalFlora po67404).

The risk Phytolacca heterotepala (Mexican pokeweed) would pose to California is evaluated below.

Consequences of Introduction:

1) Climate/Host Interaction: Phytolacca heterotepala has the ability to grow in disturbed areas of California and persist from cultivation. Since its presence has been observed in north coast and central coast areas, it may be able to spread to south coast areas of California. It is unknown if it may spread to inland areas of the state It receives a Low (1) in this category.

Evaluate if the pest would have suitable hosts and climate to establish in California. Score:

-Low (1) Not likely to establish in California; or likely to establish in very limited areas.

-Medium (2) may be able to establish in a larger but limited part of California.

-High (3) likely to establish a widespread distribution in California.

2) Known Pest Host Range: Phytolacca heterotepala does not need one particular host but grow wherever ecological conditions are favorable. It receives a High (3) in this category

Evaluate the host range of the pest. Score:

-Low (1) has a very limited host range.

-Medium (2) has a moderate host range.

-High (3) has a wide host range.

3) Pest Dispersal Potential: Phytolacca produces multiseeded fleshy berries that are eaten and dispersed by birds. It can reproduce vegetatively from root sprouts. It has not spread widely despite being present in CA for more than 100 years.. It receives a Medium (2) in this category.

Evaluate the natural and artificial dispersal potential of the pest. Score:

-Low (1) does not have high reproductive or dispersal potential.

-Medium (2) has either high reproductive or dispersal potential.

-High (3) has both high reproduction and dispersal potential.

4) Economic Impact: All parts of Phytolacca spp. (pokeweed, pokesalad) are potentially toxic to mammals (Roberge et al. 1986, FDA Poisonous Plant Database 2008. If this species spreads in California, hand pulling and foliar applications could increase production costs. Manual removal is not recommended without appropriate personal protection, and once established, eradication can be difficult. Although PAPs provide plant defence and resistance to infection by viruses and some fungus, Phytolacca is a host of pokeweed crinkle virus (, that can infect sugar beets, chard, spinach, and cucumber (Lackey 1965). However, it currently, has only been detected in urban waste areas. It has not spread to agricultural areas despite its long presence along the central coast of CA. It receives a Medium (2) in this category

Evaluate the economic impact of the pest to California using the criteria below. Score:

Economic Impact: E, F

A. The pest could lower crop yield.

B. The pest could lower crop value (includes increasing crop production costs).

C. The pest could trigger the loss of markets (includes quarantines).

D. The pest could negatively change normal cultural practices.

E. The pest can vector, or is vectored, by another pestiferous organism.

F. The organism is injurious or poisonous to agriculturally important animals.

G. The organism can interfere with the delivery or supply of water for agricultural uses.

Economic Impact Score: 2

-Low (1) causes 0 or 1 of these impacts.

-Medium (2) causes 2 of these impacts.

-High (3) causes 3 or more of these impacts.

5) Environmental Impact: Pokeweed crinkle virus can infect native California species (e.g., Adenostoma, Eriogonum), and may affect rare and endangered taxa (Lackey 1965). Phytolacca heterotepala occurs in disturbed areasand may outcompete other weeds.. It receives a Medium (2) in this category.

Environmental Impact: A

A. The pest could have a significant environmental impact such as lowering biodiversity, disrupting natural communities, or changing ecosystem processes.

B. The pest could directly affect threatened or endangered species.

C. The pest could impact threatened or endangered species by disrupting critical habitats.

D. The pest could trigger additional official or private treatment programs.

E. The pest significantly impacts cultural practices, home/urban gardening or ornamental plantings.

Score the pest for Environmental Impact. Score: 2

-Low (1) causes none of the above to occur.

-Medium (2) causes one of the above to occur.

-High (3) causes two or more of the above to occur.

Consequences of Introduction to California for Phytolacca heterotepala (Mexican pokeweed): Medium (10)

Add up the total score and include it here.

-Low = 5–8 points

-Medium = 9–12 points

-High = 13–15 points

6) Post Entry Distribution and Survey Information: Phytolacca heterotepala is naturalized in the San Francisco Bay Area (Alameda, Marin, San Francisco counties) and recently documented in San Luis Obispo County. Two historic naturalized populations (Santa Clara and Santa Barbara counties) are presumed extirpated. It receives a Low (1) in this category.

Evaluate the known distribution in California. Only official records identified by a taxonomic expert and supported by voucher specimens deposited in natural history collections should be considered. Pest incursions that have been eradicated, are under eradication, or have been delimited with no further detections should not be included.

-Not established (0) Pest never detected in California, or known only from incursions.

-Low (1) Pest has a localized distribution in California, or is established in one suitable climate/host area (region).

-Medium (2) Pest is widespread in California but not fully established in the endangered area, or pest established in two contiguous suitable climate/host areas.

-High (3) Pest has fully established in the endangered area, or pest is reported in more than two contiguous or non-contiguous suitable climate/host areas.

Final Score:

The final score is the consequences of introduction score minus the post entry distribution and survey information score: Medium (9)


Phytolacca heterotepala has been present as a weed in the San Francisco Bay Area since the 1950s. The recent interceptions in San Luis Obispo County indicate that it may be spreading. No recent surveys have been performed for this taxon in California, so it may be possible that Phytolacca heterotepala occurs elsewhere in the state. Lacking studies, there is uncertainty regarding impacts to California’s agricultural and natural resources.

If plants suspected to be Phytolacca heterotepala are found in your area, please submit samples to the nearest Agricultural Commissioner office or to Botany California Department of Food and Agriculture, Plant Pest Diagnostic Center t Botany Lab for determination and vouchering as specimens in the plant herbarium.

Conclusion and Rating Justification:

Although Phytolacca heterotepala has been present as a weed in the San Francisco Bay Area since at least 1950s, it has recently spread to San Luis Obispo County. There is potential to spread into additional, suitable habitats but these areas are disturbed and weedy in nature. Therefore, an “A” rating is justified.


Ali, M. A., J. Lee, S.-Y. Kim, S.-H. Park, and F. M. Al-Hemaid. 2015. Molecular phylogenetic analyses of internal transcribed spacer (ITS) sequences of nuclear ribosomal DNA indicate monophyly of the genus Phytolacca L. (Phytolaccaceae). Bangladesh Journal of Plant Taxonomy 22(1):1-8.

The Calflora Database [A Non-Profit Organization]. 2018. Calflora: Information on California plants for education, research and conservation, with data contributed by public and private institutions and individuals, including the Consortium of California Herbaria [web application] Accessed January 24,  2018.

California Academy of Sciences [CAS]. 2010–2018. Institute for Biodiversity Science and Sustainability, Department of Botany, California Academy of Sciences [CAS]. CAS Botany Collection Database. Accessed January 24, 2018.

Consortium of California Herbaria [CCH]. 2018. Data provided by the participants of the Consortium of California Herbaria [CCH]. Regents of the University of California 2018. Accessed January 24, 2018.

Davis, J. I. 1985. Introgression in Central American Phytolacca (Phytolaccaceae). American Journal of Botany 72(12):1944-1953.

Domingues de Almeida, J. D., and H. Freitas. 2006. Exotic naturalized flora of continental Portugal-A reassessment. Botanica complutensis 30:117-130.

FDA Poisonous Plant Database. 2008 (data updated May 2008). Accessed January 24, 2018

Howell, J. T. 1960. A Mexican pokeberry in San Francisco, California. Leafl. W. Bot. 9: 81–83.

iNaturalist. 2018. Accessed January 24, 2018.

Invasive plants in Portugal, 2016. Phytolacca Americana- Factsheet

Irvin, J. D., and F. M. Uckun. 1992. Pokeweed antiviral protein: ribosome inactivation and therapeutic applications. Pharmacology & therapeutics 55(3):279-302.

Jepson eFlora. Accessed January 24, 2018

Lackey, C. F. 1965. Pokeweed crinkle leaf, caused by a virus transmitted by dodder from desert shrubs in Southern California. Plant Disease Reporter 49(12):1002-1005.

Munz, P. A., and D. D. Keck. 1968. A California flora and supplement. University of California Press, Berkeley, CA.

Nienaber, M.A., and J. Thieret. 2004. Phytolaccaceae. Pp. ##–## in Flora North America Editorial Committee (eds.) Flora of North America North of Mexico, Vol. 4: Magnoliophyta: Caryophyllidae, Part 1. Oxford University Press, New York, NY. Accessed January 24, 2018.

Ortiz, S. 1987. Phytolacca heterotepala H. Walter en Portugal. Anales del Jardín Botánico de Madrid 44(2):555.

Phytosanitary Certificate Issuance & Tracking System (PCIT), Phytosanitary Export Database (PExD), USDA, APHIS. Accessed January 23, 2018.

Roberge, R., E. Brader, M. L. Martin, D. Jehle, T. Evans, F. Harchelroad, G. Magreni, G. Gesualdi, C. Belardi, and M. Sayre. 1986. The root of evil—pokeweed intoxication. Annals of emergency medicine 15(4):470-473.

Rzedowski, J., and G. Calderón de Rzedowski. 2000. Notas sobre el género Phytolacca (Phytolaccaceae) en México. Acta Botanica Mexicana 53:49-66.

Steinmann, V. W. 1997. Phytolacca icosandra L.(Phytolaccaceae): new to the continental United States. Madroño 44(1):108-109.

Xu, S. Z., Z. Y. Li, and X. H. Jin. 2017. DNA barcoding of invasive plants in China: A resource for identifying invasive plants. Molecular Ecology Resources


Raj Randhawa, 1220 ‘N’ Street, Room 221, Sacramento CA 95814, (916)403-6617,

Responsible Party:

Dean G. Kelch, Primary Botanist; California Department of Food and Agriculture; 1220 N Street, Sacramento, CA 95814; Tel. (916) 403-6650;[@]

Comment Period: * CLOSED

2/20/2018 – 4/6/2018


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Pest Rating: A  |  Proposed Seed Rating: R


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