Pacific Island Ecosystems at Risk (PIER)
RISK ASSESSMENT RESULTS: High risk, score: 8
|
Australian/New Zealand Weed Risk Assessment adapted for Hawai‘i. Information on Risk Assessments |
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Houttuynia cordata Thumb. Family - Saururaceae. Common Names(s) - chameleon-plant, dokudami, houttuynia. Synonym(s) - Gymnotheca chinensis, Polypara cochinchinensis. |
Answer |
Score |
||
|
1.01 |
Is the species highly domesticated? |
y=-3, n=0 |
n |
0 |
|
1.02 |
Has the species become naturalized where grown? |
y=1, n=-1 |
||
|
1.03 |
Does the species have weedy races? |
y=-1, n=-1 |
||
|
2.01 |
Species suited to tropical or subtropical climate(s) (0-low; 1-intermediate; 2-high) – If island is primarily wet habitat, then substitute “wet tropical” for “tropical or subtropical” |
See Append 2 |
1 |
|
|
2.02 |
Quality of climate match data (0-low; 1-intermediate; 2-high) see appendix 2 |
2 |
||
|
2.03 |
Broad climate suitability (environmental versatility) |
y=1, n=0 |
y |
1 |
|
2.04 |
Native or naturalized in regions with tropical or subtropical climates |
y=1, n=0 |
y |
1 |
|
2.05 |
Does the species have a history of repeated introductions outside its natural range? |
y=-2, ?=-1, n=0 |
y |
|
|
3.01 |
Naturalized beyond native range y = 1*multiplier (see Append 2), n= question 2.05 |
y |
1 |
|
|
3.02 |
Garden/amenity/disturbance weed y = 1*multiplier (see Append 2) |
n=0 |
y |
1 |
|
3.03 |
Agricultural/forestry/horticultural weed y = 2*multiplier (see Append 2) |
n=0 |
n |
0 |
|
3.04 |
Environmental weed y = 2*multiplier (see Append 2) |
n=0 |
n |
0 |
|
3.05 |
Congeneric weed y = 1*multiplier (see Append 2) |
n=0 |
n |
0 |
|
4.01 |
Produces spines, thorns or burrs |
y=1, n=0 |
n |
0 |
|
4.02 |
Allelopathic |
y=1, n=0 |
||
|
4.03 |
Parasitic |
y=1, n=0 |
n |
0 |
|
4.04 |
Unpalatable to grazing animals |
y=1, n=-1 |
||
|
4.05 |
Toxic to animals |
y=1, n=0 |
n |
0 |
|
4.06 |
Host for recognized pests and pathogens |
y=1, n=0 |
||
|
4.07 |
Causes allergies or is otherwise toxic to humans |
y=1, n=0 |
n |
0 |
|
4.08 |
Creates a fire hazard in natural ecosystems |
y=1, n=0 |
n |
0 |
|
4.09 |
Is a shade tolerant plant at some stage of its life cycle |
y=1, n=0 |
y |
1 |
|
4.10 |
Tolerates a wide range of soil conditions (or limestone conditions if not a volcanic island) |
y=1, n=0 |
n |
0 |
|
4.11 |
Climbing or smothering growth habit |
y=1, n=0 |
n |
0 |
|
4.12 |
Forms dense thickets |
y=1, n=0 |
n |
0 |
|
5.01 |
Aquatic |
y=5, n=0 |
n |
0 |
|
5.02 |
Grass |
y=1, n=0 |
n |
0 |
|
5.03 |
Nitrogen fixing woody plant |
y=1, n=0 |
n |
0 |
|
5.04 |
Geophyte (herbaceous with underground storage organs -- bulbs, corms, or tubers) |
y=1, n=0 |
n |
0 |
|
6.01 |
Evidence of substantial reproductive failure in native habitat |
y=1, n=0 |
n |
0 |
|
6.02 |
Produces viable seed. |
y=1, n=-1 |
y |
1 |
|
6.03 |
Hybridizes naturally |
y=1, n=-1 |
||
|
6.04 |
Self-compatible or apomictic |
y=1, n=-1 |
y |
1 |
|
6.05 |
Requires specialist pollinators |
y=-1, n=0 |
n |
0 |
|
6.06 |
Reproduction by vegetative fragmentation |
y=1, n=-1 |
y |
1 |
|
6.07 |
Minimum generative time (years) 1 year = 1, 2 or 3 years = 0, 4+ years = -1 |
See left |
1 |
1 |
|
7.01 |
Propagules likely to be dispersed unintentionally (plants growing in heavily trafficked areas) |
y=1, n=-1 |
y |
1 |
|
7.02 |
Propagules dispersed intentionally by people |
y=1, n=-1 |
y |
1 |
|
7.03 |
Propagules likely to disperse as a produce contaminant |
y=1, n=-1 |
n |
-1 |
|
7.04 |
Propagules adapted to wind dispersal |
y=1, n=-1 |
n |
-1 |
|
7.05 |
Propagules water dispersed |
y=1, n=-1 |
||
|
7.06 |
Propagules bird dispersed |
y=1, n=-1 |
n |
-1 |
|
7.07 |
Propagules dispersed by other animals (externally) |
y=1, n=-1 |
n |
-1 |
|
7.08 |
Propagules survive passage through the gut |
y=1, n=-1 |
||
|
8.01 |
Prolific seed production (>1000/m2) |
y=1, n=-1 |
||
|
8.02 |
Evidence that a persistent propagule bank is formed (>1 yr) |
y=1, n=-1 |
||
|
8.03 |
Well controlled by herbicides |
y=-1, n=1 |
||
|
8.04 |
Tolerates, or benefits from, mutilation, cultivation, or fire |
y=1, n=-1 |
y |
1 |
|
8.05 |
Effective natural enemies present locally (e.g. introduced biocontrol agents) |
y=-1, n=1 |
||
|
Total score: |
8 |
|||
Supporting data:
|
Notes |
Source |
|
|
1.01 |
No evidence. |
|
|
1.02 |
||
|
1.03 |
||
|
2.01 |
(1) Native to: China, Japan, Taiwan, Bhutan, Nepal [range and hardiness (see 2.03) suggest this species is marginally subtropical] |
(1) http://www.ars-grin.gov/cgi-bin/npgs/html/taxon.pl?102694 [Cited 2009 July 9]. |
|
2.02 |
(1) Native to: China, Japan, Taiwan, Bhutan, Nepal |
(1) http://www.ars-grin.gov/cgi-bin/npgs/html/taxon.pl?102694 [Cited 2009 July 9]. |
|
2.03 |
(1) Houttuynia’s natural habitats are moist loamy soils, shallow water and low light situations. It thrives along the margins of ponds and waterways. (2) USDA Hardiness Zones 5 - 9. (3) Near sea level to 2500 m. |
(1) http://www.envbop.govt.nz/Environment/Weed328.aspx [Cited 2009 July10]. (2) http://davesgarden.com/guides/pf/go/2164/ [Cited 2009 July 10]. (3) http://www.efloras.org/florataxon.aspx?flora_id=2&taxon_id=200005537 [Cited 2009 July 10] |
|
2.04 |
(1) Native to: China, Japan, Taiwan, Bhutan, Nepal (2) Houttuynia’s natural habitats are moist loamy soils, shallow water and low light situations. It thrives along the margins of ponds and waterways. (3) USDA Hardiness Zones 5 - 9. (4) Near sea level to 2500 m. |
(1) http://www.ars-grin.gov/cgi-bin/npgs/html/taxon.pl?102694 [Cited 2009 July 9]. (2) http://www.envbop.govt.nz/Environment/Weed328.aspx [Cited 2009 July10]. (3) http://davesgarden.com/guides/pf/go/2164/ [Cited 2009 July 10]. (4) http://www.efloras.org/florataxon.aspx?flora_id=2&taxon_id=200005537 [Cited 2009 July 10] |
|
2.05 |
(1) Introduced to New Zealand as an ornamental. (2) Vietnamese vendors sell Houttuynia cordata in Chinatown in Honolulu, Hawaii. (3) Grown as a vegetable in Vietnam. (4) Dave's Garden has Houttuynia for sale. |
(1)
http://www.arc.govt.nz/albany/fms/main/Documents/Environment/Plants%20and%20animals/ |
|
3.01 |
(1) Houttuynia cordata is naturalized in South Korea. (2) Naturalized in Vietnam. |
(1) Kil J. H., Shim K.C., Park S.H., Koh K.S., Suh M.H., Ku Y.B., Suh S.U., Oh H.K., Kong H.Y. 2004. "Distributions of Naturalized Alien Plants in South Korea." Weed Technology 18: 1493-1495. (2) http://www.avrdc.org/publications/socio/veg_industry/Vietnam.pdf [Cited 2009 July 9]. |
|
3.02 |
(1) Houttuynia cordata has not yet naturalised in Aukland, New Zealand. However, it is classified as a Total Control Pest Plant: effects are major, incidence of the pest is low. Eradication realistic. It is being controlled because of its invasiveness. Its aggressive and invasive spreading habit allows it to form dense colonies which can smother large areas of wetland marshes or forest floor, preventing native plant regeneration or growth. Its vigorous growth quickly crowds out smaller plants leading to a long-term modification of forest and wetland ecosystems. (2) The Consolidated List of Environmental Weeds in New Zealand lists Houttuynia cordata as not know outside of cultivation. (3) Perennial plant that has not escaped confinement, there is much fear that it will eventually present a huge risk to native habitats. (4) Picture of Houttuynia escaping garden planting. No control mentioned. (5) U.C. Davis Botanical Garden blog mentions Houttuynia as a garden pest and that it should be labled as invasive when sold. (6) Lady Bird Johnson Wildflower Center Blog mentions Houtuynia cordata as an aggressive invasive that is difficult to control due to root fragments. |
(1)
http://www.arc.govt.nz/albany/fms/main/Documents/Environment/Plants%20and%20animals/ |
|
3.03 |
(1) Houttuynia cordata has not yet naturalized in Aukland, New Zealand. However, it is classified as a Total Control Pest Plant: effects are major, incidence of the pest is low. Eradication realistic. It is being controlled because of its invasiveness. Its aggressive and invasive spreading habit allows it to form dense colonies which can smother large areas of wetland marshes or forest floor, preventing native plant regeneration or growth. Its vigorous growth quickly crowds out smaller plants leading to a long-term modification of forest and wetland ecosystems. (2) The Consolidated List of Environmental Weeds in New Zealand lists Houttuynia cordata as not know outside of cultivation. (3) Perennial plant that has not escaped confinement, there is much fear that it will eventually present a huge risk to native habitats. |
(1)
http://www.arc.govt.nz/albany/fms/main/Documents/Environment/Plants%20and%20animals/ |
|
3.04 |
Not currently, but see following concerns. (1) Houttuynia cordata has not yet naturalized in Aukland, New Zealand. However, it is classified as a Total Control Pest Plant: effects are major, incidence of the pest is low. Eradication realistic. It is being controlled because of its invasiveness. Its aggressive and invasive spreading habit allows it to form dense colonies which can smother large areas of wetland marshes or forest floor, preventing native plant regeneration or growth. Its vigorous growth quickly crowds out smaller plants leading to a long-term modification of forest and wetland ecosystems. (2) The Consolidated List of Environmental Weeds in New Zealand lists Houttuynia cordata as not know outside of cultivation. (3) Perennial plant that has not escaped confinement, there is much fear that it will eventually present a huge risk to native habitats. |
(1)
http://www.arc.govt.nz/albany/fms/main/Documents/Environment/Plants%20and%20animals/ |
|
3.05 |
(1) Houttuynia cordata is the only species in the genus Houttuynia. |
(1) http://www.efloras.org/florataxon.aspx?flora_id=2&taxon_id=115808 [Cited 2009 July 10] |
|
4.01 |
(1) Houttuynia is a perennial, herbaceous deciduous ground cover that has slender rhizomes from which arise numerous thin erect stems. These bear alternate, unlobed, sometimes angular, five-veined, heart-shaped leaves up to 7.5cm across. The leaves display an array of colour combinations i.e., yellow, green, bronze and scarlet red (the last most pronounced in sunny locations). The plant can be anywhere from 15cm to 60cm in height, depending upon the situation it is growing in. It produces small white flowers during summer in short erect spikes. |
(1)
http://www.arc.govt.nz/albany/fms/main/Documents/Environment/Plants%20and%20animals/ |
|
4.02 |
Unknown (1) An aqueous solution of stems and leaves of Houttuynia cordata suppressed germination and growth of two rice paddy weeds, Echinochloa and Monocharia. |
(1) Lin D., Sugitomo Y., Dong Y., Terao H., Matsuo M. 2006 Natural herbicidal potential of Saururaceae (Houttuynia cordata Thunb) dried powders on paddy weeds in transplanted rice. Crop Protection 25:1126-1129. |
|
4.03 |
(1) Not parasitic. |
(1) http://www.parasiticplants.siu.edu/ListParasites.html [Cited 2009 July 10]. |
|
4.04 |
Unknown |
|
|
4.05 |
(1) No evidence of toxicity in PubMed. (2) No evidence of toxicity in ToxNet. |
(1) http://www.ncbi.nlm.nih.gov/sites/entrez [Cited 2009 July 10]. (2) http://toxnet.nlm.nih.gov/cgi-bin/sis/search [Cited 2009 July 10]. |
|
4.06 |
Unknown |
|
|
4.07 |
(1) No evidence of toxicity in PubMed. (2) No evidence of toxicity in ToxNet. (3) Vietnamese vendors sell Houttuynia cordata in Chinatown in Honolulu, Hawaii. (4) Grown as a vegetable in Vietnam. |
(1) http://www.ncbi.nlm.nih.gov/sites/entrez [Cited 2009 July 10]. (2) http://toxnet.nlm.nih.gov/cgi-bin/sis/search [Cited 2009 July 10]. (3) http://www.ethnobotanyjournal.org/vol6/i1547-3465-06-063.pdf [Cited 2009 July 9]. (4) http://www.avrdc.org/publications/socio/veg_industry/Vietnam.pdf [Cited 2009 July9]. |
|
4.08 |
(1) Houttuynia’s natural habitats are moist loamy soils, shallow water and low light situations. It thrives along the margins of ponds and waterways. A deciduous, perennial, creeping herb used as a ground cover that can grow to 70cm tall. |
(1) http://www.envbop.govt.nz/Environment/Weed328.aspx [Cited 2009 July 10]. |
|
4.09 |
(1) Houttuynia cordata grows best in shallow water or moist loamy soils. Its growth is moderated by drier, but not totally dry, soil in full sun. (2) The Nature Conservancy (2001) reports that H. cordata can be found in shaded places in lowlands and forested banks. "H. cordata's natural habitats are moist loamy soils, shallow water and low light situations. (3) Shade-tolerant. |
(1) http://www.arc.govt.nz/albany/fms/main/Documents/Environment/Plants%20and%20animals/ |
|
4.10 |
(1) Houttuynia cordata grows best in shallow water or moist loamy soils. Its growth is moderated by drier, but not totally dry, soil in full sun. (2) Houttuynia’s natural habitats are moist loamy soils. (3) Soil pH requirements: 6.1 to 6.5 (mildly acidic). |
(1)
http://www.arc.govt.nz/albany/fms/main/Documents/Environment/Plants%20and%20animals/ |
|
4.11 |
(1) Houttuynia is a perennial, herbaceous deciduous ground cover that has slender rhizomes from which arise numerous thin erect stems. These bear alternate, unlobed, sometimes angular, five-veined, heart-shaped leaves up to 7.5cm across. The leaves display an array of colour combinations i.e., yellow, green, bronze and scarlet red (the last most pronounced in sunny locations). The plant can be anywhere from 15cm to 60cm in height, depending upon the situation it is growing in. It produces small white flowers during summer in short erect spikes. |
(1) Houttuynia cordata grows best in shallow water or moist loamy soils. Its growth is moderated by drier, but not totally dry, soil in full sun. |
|
4.12 |
(1) Houttuynia is a perennial, herbaceous deciduous ground cover that has slender rhizomes from which arise numerous thin erect stems. These bear alternate, unlobed, sometimes angular, five-veined, heart-shaped leaves up to 7.5cm across. The leaves display an array of colour combinations i.e., yellow, green, bronze and scarlet red (the last most pronounced in sunny locations). The plant can be anywhere from 15cm to 60cm in height, depending upon the situation it is growing in. It produces small white flowers during summer in short erect spikes. |
(1)
http://www.arc.govt.nz/albany/fms/main/Documents/Environment/Plants%20and%20animals/ |
|
5.01 |
(1) Houttuynia is a perennial, herbaceous deciduous ground cover that has slender rhizomes from which arise numerous thin erect stems. These bear alternate, unlobed, sometimes angular, five-veined, heart-shaped leaves up to 7.5cm across. The leaves display an array of colour combinations i.e., yellow, green, bronze and scarlet red (the last most pronounced in sunny locations). The plant can be anywhere from 15cm to 60cm in height, depending upon the situation it is growing in. It produces small white flowers during summer in short erect spikes. However (2) Hynes (2003, personal communication) reports that, "Not only is H. cordata able to seed parthenogenetically (in the absence of male plants), but also every segment of it roots readily and grows effortlessly." Furthermore the author has noticed it being sold as a water plant in nurseries and states that, "Obviously it can live in water as well as in soil." Hynes (2003) correlates H. cordata's spread with its immense appeal "Because of the huge range of colours each leaf has but should someone in the nursery trade decide to push it - we will have a major pest that will be almost ineradicable." |
(1)
http://www.arc.govt.nz/albany/fms/main/Documents/Environment/Plants%20and%20animals/ |
|
5.02 |
(1) Saururaceae |
(1) http://www.ars-grin.gov/cgi-bin/npgs/html/taxon.pl?102694 [Cited 2009 July 9]. |
|
5.03 |
(1) Houttuynia is a perennial, herbaceous deciduous ground cover that has slender rhizomes from which arise numerous thin erect stems. These bear alternate, unlobed, sometimes angular, five-veined, heart-shaped leaves up to 7.5cm across. The leaves display an array of colour combinations i.e., yellow, green, bronze and scarlet red (the last most pronounced in sunny locations). The plant can be anywhere from 15cm to 60cm in height, depending upon the situation it is growing in. It produces small white flowers during summer in short erect spikes. |
(1)
http://www.arc.govt.nz/albany/fms/main/Documents/Environment/Plants%20and%20animals/ |
|
5.04 |
(1) Houttuynia is a perennial, herbaceous deciduous ground cover that has slender rhizomes from which arise numerous thin erect stems. These bear alternate, unlobed, sometimes angular, five-veined, heart-shaped leaves up to 7.5cm across. The leaves display an array of colour combinations i.e., yellow, green, bronze and scarlet red (the last most pronounced in sunny locations). The plant can be anywhere from 15cm to 60cm in height, depending upon the situation it is growing in. It produces small white flowers during summer in short erect spikes. |
(1)
http://www.arc.govt.nz/albany/fms/main/Documents/Environment/Plants%20and%20animals/ |
|
6.01 |
No evidence |
|
|
6.02 |
(1) The plant spreads by both seeds and rhizome fragments. Once established Houttuyina can cover large areas assisted by creeping stolons and an extensive root system. It will also set viable seed. |
(1) http://www.envbop.govt.nz/Environment/Weed328.aspx [Cited 2009 July 10]. |
|
6.03 |
Unknown |
|
|
6.04 |
(1) Houttuynia cordata can form seeds parthenogenetically (from an unfertilised egg cell) |
(1)
http://www.arc.govt.nz/albany/fms/main/Documents/Environment/Plants%20and%20animals/ |
|
6.05 |
(1) Houttuynia cordata can form seeds parthenogenetically (from an unfertilised egg cell) |
(1)
http://www.arc.govt.nz/albany/fms/main/Documents/Environment/Plants%20and%20animals/ |
|
6.06 |
(1) Houttuynia cordata spreads by seeds and plant fragments. The fragments can sprout roots and form new infestations. |
(1)
http://www.arc.govt.nz/albany/fms/main/Documents/Environment/Plants%20and%20animals/ |
|
6.07 |
(1) High reproductive and growth rate. (2) Houttuynia cordata spreads by seeds and plant fragments. The fragments can sprout roots and form new infestations. |
(1) http://www.issg.org/database/species/ecology.asp?si=854
[Cited 2009 July 10]. (2)
http://www.arc.govt.nz/albany/fms/main/Documents/Environment/Plants%20and%20animals/ |
|
7.01 |
(1) Houttuynia cordata spreads through plant fragments being moved intentionally or on cultivation equipment and in garden refuse. (2) Risk of spread through garden waste. |
(1)
http://www.arc.govt.nz/albany/fms/main/Documents/Environment/Plants%20and%20animals/ |
|
7.02 |
(1) Vietnamese vendors sell Houttuynia cordata in Chinatown in Honolulu, Hawaii. (2) Grown as a vegetable in Vietnam. (3) Dave's Garden has Houttuynia for sale. |
(1) http://www.ethnobotanyjournal.org/vol6/i1547-3465-06-063.pdf [Cited 2009 July 9]. (2) http://www.avrdc.org/publications/socio/veg_industry/Vietnam.pdf [Cited 2009 July9]. (3) http://davesgarden.com/guides/pf/b/Saururaceae/Houttuynia/none/cultivar/0/ |
|
7.03 |
Unlikely (1) Capsule 2-3 mm, with persistent styles |
(1) http://www.efloras.org/florataxon.aspx?flora_id=2&taxon_id=200005537 [Cited 2009 July 10]. |
|
7.04 |
No adaptation for wind dispersal. (1) Capsule 2-3 mm, with persistent styles |
(1) http://www.efloras.org/florataxon.aspx?flora_id=2&taxon_id=200005537 [Cited 2009 July 10]. |
|
7.05 |
Unknown (1) Capsule 2-3 mm, with persistent styles (2) Houttuynia’s natural habitats are moist loamy soils, shallow water and low light situations. It thrives along the margins of ponds and waterways |
(1) http://www.efloras.org/florataxon.aspx?flora_id=2&taxon_id=200005537 [Cited 2009 July 10]. (2) http://www.envbop.govt.nz/Environment/Weed328.aspx [Cited 2009 July10]. |
|
7.06 |
Not a fleshy berry. (1) Capsule 2-3 mm, with persistent styles |
(1) http://www.efloras.org/florataxon.aspx?flora_id=2&taxon_id=200005537 [Cited 2009 July 10]. |
|
7.07 |
No means of attachment. (1) Capsule 2-3 mm, with persistent styles |
(1) http://www.efloras.org/florataxon.aspx?flora_id=2&taxon_id=200005537 [Cited 2009 July 10]. |
|
7.08 |
Unknown. (1) Capsule 2-3 mm, with persistent styles |
(1) http://www.efloras.org/florataxon.aspx?flora_id=2&taxon_id=200005537 [Cited 2009 July 10]. |
|
8.01 |
Unknown |
|
|
8.02 |
Unknown |
|
|
8.03 |
Unknown (1) Both the Environment Bay of Plenty (2003) and the National Pest Plant Accord (2001) report that certain herbicides may be used to control H. cordata but neither source details which herbicides to use for reasons that it is mostly a garden weed currently and extra caution must be used when applying herbicides in garden environment. If herbicide use are desired it is best to contact local authorities for further assistance and information. |
(1) http://www.issg.org/database/species/ecology.asp?si=854 [Cited 2009 July 10]. |
|
8.04 |
(1) Houttuynia cordata spreads through plant fragments being moved intentionally or on cultivation equipment and in garden refuse. (2) Houttuynia cordata spreads by seeds and plant fragments. The fragments can sprout roots and form new infestations. |
(1)
http://www.arc.govt.nz/albany/fms/main/Documents/Environment/Plants%20and%20animals/ |
|
8.05 |
Unknown |
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