Laportea canadensis

Canadian wood-nettle and photographed at Brooklyn Botanic Garden in September — Canadian wood-nettle (Laportea canadensis), photographed at Brooklyn Botanic Garden (New York) in September. Photo By: Raffi Kojian (http://Gardenology.org) [CC BY-SA 3.0], via Wikimedia Commons

California Pest Rating for

Laportea canadensis)

Pest Rating: D | Proposed Seed Rating: N/A

PEST RATING PROFILE

Initiating Event:

This plant has been rated as “Q” by the CDFA Botany Lab in response to a border detection.

History & Status:

Wood nettle is a common perennial herb native to eastern North America, where it is found growing in moist to wet soil in the understory of Eastern Deciduous Forests. It has a strong family resemblance to the common nettle (Urtica dioica), but unlike most other members of the nettle family, it has alternate leaves. These leaves are broadly heart-shaped with a toothed margin. The plant is sparsely covered by stinging hairs. The effect of touching it is similar to touching common nettles, but not as severe. Native Americans used wood nettle to treat incontinence and tuberculosis, to counteract poison, as a love medicine, and to facilitate childbirth.

Official Control: There is no known official control at this time.

California Distribution: None.

California Interceptions: A new interception was made in Yolo County on 6/14/2017 (PDR NE0P06655513).

Consequences of Introduction:

1) Climate/Host Interaction: Evaluate if the pest would have suitable hosts and climate to establish in California.

Risk is Low (1), as the preferred habitat of wood nettle (moist, dense, deciduous forest) does not occur in California. Score: 1

– 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: Evaluate the host range of the pest. Risk is High (3) as weeds do not require any one host, but grow wherever ecological conditions are favorable. Score: 3

– 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: Evaluate the natural and artificial dispersal potential of the pest. Risk is Medium (2). The plant produces numerous seeds that are apparently able to spread via water distribution. Patches may be the result of root sprouting. Score: 2

– 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: Evaluate the likely economic impacts of the pest to California using the criteria below.

Economic Impact:

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: Risk is Low (1). No economic impact, even where it is common in Eastern North America.

– 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: Evaluate the environmental impact of the pest on California using the criteria below.

Environmental Impact:

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.

Environmental Impact Score: Low (1). The plant is well integrated into its native landscape, and is not known to be weedy. It is unlikely to be adapted to any part of California.

– 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 wood nettle:

Add up the total score and include it here. (8)

–Low = 5-8 points

–Medium = 9-12 points

–High = 13-15 points

6) Post Entry Distribution and Survey Information: 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. (0)

–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:

7) The final score is the consequences of introduction score minus the post entry distribution and survey information score: (8)

Uncertainty:

Wood nettle is poorly adapted to California and it is not known to be weedy elsewhere; there is low uncertainty.

Conclusion and Rating Justification:

An Eastern woodland native. A D rating is recommended.

References:

Consortium of California Herbaria (ucjeps.berkeley.edu/consortium/).

‪ Flora of North America Editorial Committee, eds. 1993+. Flora of North America North of Mexico. 16+ vols. New York and Oxford.

Moerman, Daniel E. 1986. Medicinal plants of native America. Museum of Anthropology, University of Michigan, Ann Arbor.

Responsible Party:

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

NOTE:

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