Pacific Island Ecosystems at Risk (PIER)


Hygrophila polysperma


RISK ASSESSMENT RESULTS: High risk, score: 20


Australian/New Zealand Weed Risk Assessment adapted for Hawai‘i.
Information on Risk Assessments
Original risk assessment

Hygrophila polysperma (Roxb.) T. Anders. Family - Acanthaceae . Common Names(s) - East Indian swampweed, hygro, Indian swampweed, Miramar-weed . Synonym(s) - Justicia polysperma Roxb.

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

2

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

2

3.02

Garden/amenity/disturbance weed y = 1*multiplier (see Append 2)

n=0

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

y

4

3.05

Congeneric weed y = 1*multiplier (see Append 2)

n=0

y

2

4.01

Produces spines, thorns or burrs

y=1, n=0

n

0

4.02

Allelopathic

y=1, n=0

n

0

4.03

Parasitic

y=1, n=0

n

0

4.04

Unpalatable to grazing animals

y=1, n=-1

y

1

4.05

Toxic to animals

y=1, n=0

n

0

4.06

Host for recognized pests and pathogens

y=1, n=0

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

y

1

5.01

Aquatic

y=5, n=0

y

5

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

6.05

Requires specialist pollinators

y=-1, 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 year

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

y

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

n

-1

8.01

Prolific seed production (>1000/m2)

y=1, n=-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

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:

20

Supporting data:

Notes

Source

1.01

No evidence of domestication.

 

1.02

1.03

2.01

(1) Native to Asia-Temperate: China - Guangdong, Guangxi, Yunnan; Asia-Tropical: Bangladesh, Bhutan, India, Nepal, Pakistan, Cambodia, Laos, Myanmar, Thailand, Vietnam

(1) http://www.ars-grin.gov/cgi-bin/npgs/html/taxon.pl?316380#syn

2.02

(1) Native to Asia-Temperate: China - Guangdong, Guangxi, Yunnan; Asia-Tropical: Bangladesh, Bhutan, India, Nepal, Pakistan, Cambodia, Laos, Myanmar, Thailand, Vietnam

(1) http://www.ars-grin.gov/cgi-bin/npgs/html/taxon.pl?316380#syn

2.03

(1)Tolerates a range of pH and water hardness conditions. Temperature tolerance: minimum temperature, 4o C (39o F); optimum temperature, 22-28o C (71-82o F); maximum temperature, 30o C (86o F)

(1) http://plants.ifas.ufl.edu/node/191 [cited 2008 Oct 21]. Center for Aquatic and Invasive Plants.

2.04

(1) Native to Asia-Temperate: China - Guangdong, Guangxi, Yunnan; Asia-Tropical: Bangladesh, Bhutan, India, Nepal, Pakistan, Cambodia, Laos, Myanmar, Thailand, Vietnam

(1) http://www.ars-grin.gov/cgi-bin/npgs/html/taxon.pl?316380#syn

2.05

(1) Hygrophila polysperma plant fragments are being created and released daily down the San Marcos River, Texas due to recreational usage, harvesting and environmental factors. (2) H. polysperma first recorded in the Mexican flora from a distribution in Tamaulipas, Mexico. (3) H. polysperma is one of the hardiest aquarium plants available. (4) Hygrophila polysperma continues to be sold through aquarium supply dealers and over the Internet, even though the plant is on the U.S. Federal Noxious Weed List. 

(1) Owens, C. S., J. D. Madsen, et al. (2001). "Dispersal of native and nonnative aquatic plant species in the San Marcos River, Texas." Journal of Aquatic Plant Management 39: 75-79. (2) Mora-Olivo, A., T. F. Daniel, et al. (2008). "First record in the Mexican flora of Hygrophila polysperma (Acanthaceae), an aquatic weed." Revista Mexicana de Biodiversidad 79(1): 265-269. (3) http://www.tropica.dk/productcard_1.asp?id=050 [Cited 2008 Oct 21]. (4) http://plants.ifas.ufl.edu/node/191 [Cited 2008 Oct 21] 

3.01

(1) H. polysperma has naturalized in the United States. (2) Naturalized in Texas and Florida.

(1) http://www.ars-grin.gov/cgi-bin/npgs/html/taxon.pl?316380#syn (2) http://www.fleppc.org/id_book/hygrophila%20polysperma.pdf

3.02

3.03

(1) Aquatic noxious weed in Alabama, California, Florida, Massachusetts, Minnesota, North Carolina, Oklahoma, South Carolina, Vermont

(1) http://www.ars-grin.gov/cgi-bin/npgs/html/taxon.pl?316380#syn

3.04

(1) Outcompetes natives, monoculture stands don't provide habitat for invertebrate, fish, and wildlife species. Forms dense mats over water surface, decreasing light penetration and native SAV growth. Impacts native species of multiple trophic levels. Decomposition of large stands can result in anoxic conditions. (2) Cited on Florida'a Exotic Pest Plant Council's 2007 List of Invasive Plant Species as a category 1 species. Invasive exotics that are altering native plant communities by displacing native species, changing community structuresor ecological functions, or hybridizing with natives.

(1) http://dnr.wisconsin.gov/invasives/classification/pdfs/LR_Hygrophila_polysperma.pdf (2) http://www.fleppc.org/list/07list_ctrfld.pdf [Cited 2008 Oct 21].

3.05

(1) In Australia Hygrophila costata has naturalised and become weedy in south-eastern Queensland and north-eastern New South Wales. 

(1) http://www.dpi.nsw.gov.au/agriculture/pests-weeds/weeds/profiles/hygrophila [Cited 2008 Oct 21].

4.01

(1) No spines, thorns or burrs.

(1) http://plants.ifas.ufl.edu/node/191 [Cited 2008 Oct 21].

4.02

No evidence of allelopathy

4.03

Not parasitic.

4.04

(1) Ctenopharyngodon idella Val (Cuvier and Valenciennes), that control many aquatic weed species are ineffective in controlling hygrophila because the plants appear to be unpalatable to these fish.

(1) Cuda, J.P. Sutton, D.L. 2000. Is the aquatic weed Hygrophila, Hygrophila polysperma (Polemoniales: Acanthaceae), a suitable target for classical biocontrol? Proceedings of the X International Symposium on Biological Control of Weeds 337:4-14 July 1999, Montana State University, Bozeman, Montana, USA

4.05

No evidence of toxicity.

4.06

No evidence.

4.07

No evidence.

4.08

(1) Aquatic noxious weed.

(1) http://www.ars-grin.gov/cgi-bin/npgs/html/taxon.pl?316380#syn

4.09

(1) In the submersed state, H. polysperma has low light compensation and saturation points for photosynthesis. It is a shade-adapted plant.

(1) Spencer, W. and G. Bowes. 1985. Limnophila and Hygrophiala: A review and physiological assessment of their weed potential in Florida. Journal of Aquatic Plant Management. 23:7-16.

4.10

(1) Aquatic noxious weed.

(1) http://www.ars-grin.gov/cgi-bin/npgs/html/taxon.pl?316380#syn

4.11

(1) Aquatic noxious weed.

(1) http://www.ars-grin.gov/cgi-bin/npgs/html/taxon.pl?316380#syn

4.12

(1) Able to form dense monocultural stands with immersed stem tips from depths of 3m (10 ft.). (2) Forms dense stands of stems in the water.

(1) http://www.fleppc.org/id_book/hygrophila%20polysperma.pdf {Cited 2008 Oct 21]. (2) http://plants.ifas.ufl.edu/node/191 [Cited 2008 Oct 21]

5.01

(1) Aquatic noxious weed in Alabama, California, Florida, Massachusetts, Minnesota, North Carolina, Oklahoma, South Carolina, Vermont

(1) http://www.ars-grin.gov/cgi-bin/npgs/html/taxon.pl?316380#syn

5.02

(1) Acanthaceae

(1) http://www.ars-grin.gov/cgi-bin/npgs/html/taxon.pl?316380#syn

5.03

(1) Aquatic

(1) http://www.ars-grin.gov/cgi-bin/npgs/html/taxon.pl?316380#syn

5.04

(1) Aquatic not geophyte.

(1) http://www.ars-grin.gov/cgi-bin/npgs/html/taxon.pl?316380#syn

6.01

No evidence

6.02

(1) Reproduces from seed, however it is unknown if seeds contribute much to its spread. (2) In India seeds are used medicinally.

(1) http://plants.ifas.ufl.edu/node/191 [cited 2008 Oct 21]. Center for Aquatic and Invasive Plants. (2) http://plants.ifas.ufl.edu/node/191

6.03

Don't know

6.04

Unknown

6.05

No evidence, but related species are entomophilous (1)Entomophilous plants of H. pogonocalyx are mostly pollinated by honeybees. (2)Reproductive type, pollination. Fertile flowers hermaphrodite. Unisexual flowers absent. Plants hermaphrodite. Entomophilous. Pollination mechanism conspicuously specialized, or unspecialized.

(1)Huang, J-C., Wei-Kuang Wang, Kuo-Hsiang Hong and Tzen-Yuh Chiang. 2001. Population differentiation and phylogeography of Hygrophila pogonocalyx based on RAPDs fingerprints. Aquatic Botany 70: 269–280. (2)http://florabase.calm.wa.gov.au/browse/profile/22087

6.06

(1) H. polysperma forms adventitious roots at the nodes which aids fragments to root.

(1) Spencer, W. and G. Bowes. 1985. Limnophila and Hygrophiala: A review and physiological assessment of their weed potential in Florida. Journal of Aquatic Plant Management. 23:7-16.

6.07

(1) Able to expand rapidly, in one case from 0.04 ha (0.1 acres) to 0.41 ha (10 acres) in 1 year.

(1) http://www.fleppc.org/id_book/hygrophila%20polysperma.pdf

7.01

(1) Hygrophila polysperma plant fragments are being created and released daily down the San Marcos River, Texas due to recreational usage, harvesting and environmental factors

(1) Owens, C. S., J. D. Madsen, et al. (2001). "Dispersal of native and nonnative aquatic plant species in the San Marcos River, Texas." Journal of Aquatic Plant Management 39: 75-79.

7.02

(1) H. polysperma is one of the hardiest aquarium plants available. (2) Hygrophila polysperma continues to be sold through aquarium supply dealers and over the Internet, even though the plant is on the U.S. Federal Noxious Weed List.

(1) http://www.tropica.dk/productcard_1.asp?id=050 [Cited 2008 Oct 21]. (2) http://plants.ifas.ufl.edu/node/191 [Cited 2008 Oct 21]

7.03

No evidence

7.04

(1) Water dispersed

(1) http://www.se-eppc.org/pubs/ww/birdsSummer2002.pdf

7.05

(1) Aquatic noxious weed. (2) Water dispersed.

(1) http://www.ars-grin.gov/cgi-bin/npgs/html/taxon.pl?316380#syn (2) http://www.se-eppc.org/pubs/ww/birdsSummer2002.pdf

7.06

(1) Water dispersed

(1)http://www.se-eppc.org/pubs/ww/birdsSummer2002.pdf

7.07

(1) Water dispersed

(1) http://www.se-eppc.org/pubs/ww/birdsSummer2002.pdf

7.08

No evidence

8.01

(1)Probably not, fruit a capsule with 20-30 seeds. (2) H. polysperma reproduction by seeds is uncommon in Florida.

(1) http://www.lucidcentral.org/keys/FNW/FNW%20seeds/html/fact%20sheets/Hygrophila%20polysperma.htm [Cited 2008 Oct 21].(2) Spencer, W. and G. Bowes. 1985. Limnophila and Hygrophiala: A review and physiological assessment of their weed potential in Florida. Journal of Aquatic Plant Management. 23:7-16

8.02

Don't know

8.03

(1) H. polysperma is resistant to available herbicides even when applied at maximum label rates. (2) H. polysperma is much more difficult to control with herbicides than is hydrilla, and requires higher rates of herbicides. (3)Treatments using copper plus Reward herbicides combined showed little effect on H. polysperma in Florida canals 4 weeks after application (4) From the University of Florida Aquatic Weed Management Guide, Vandiver 1999: According to this Guide, the only herbicide labeled to be used against hygrophila is "Aquathol Super K Granular Aquatic Herbicide", having the active ingredient, "endothall". (5) Herbicides typically used for controlling hygrophila are expensive, costing between $988 to $1482 per hectare. Treatment costs are even higher when labor and equipment are included. An extreme case involved the use of fluridone in a flowing water system. Control of hygrophila was achieved for a period of 20 months at a cost of $34,580 per hectare.

(1) Schmitz, D.C., Nelson, B.V., Nall, L.E., and Schardt, J.D. 1988. Exotic aquatic plants in Florida: a historical perspective and review of the present aquatic plant regulation program. Proceedings of the Symposium on Exotic Pest Plants, November 2-4, 1988, University of Miami, Miami, Florida Technical Report NPS/NREVER/NRTR -91/06 p 303-326 (2) Hall DW, Vandiver VV Jr. 1990. Weeds in Florida. Gainesville: University of Florida, Institute of Food and Agricultural Sciences (IFAS). Publication SP 37. 43 pp. (3) Sutton DL. 1995. Hygrophila is replacing hydrilla in south Florida. Aquatics 17:4-10. (4)http://plants.ifas.ufl.edu/node/191 (5) Cuda, J.P. Sutton, D.L. 2000. Is the aquatic weed Hygrophila, Hygrophila polysperma (Polemoniales: Acanthaceae), a suitable target for classical biocontrol? Proceedings of the X International Symposium on Biological Control of Weeds 337:4-14 July 1999, Montana State University, Bozeman, Montana, USA

8.04

(1) Hygrophila polysperma plant fragments are being created and released daily down the San Marcos River, Texas due to recreational usage, harvesting and environmental factors

(1) Owens, C. S., J. D. Madsen, et al. (2001). "Dispersal of native and nonnative aquatic plant species in the San Marcos River, Texas." Journal of Aquatic Plant Management 39: 75-79. (2) Mora-Olivo, A., T. F. Daniel, et al. (2008). "First record in the Mexican flora of Hygrophila polysperma (Acanthaceae), an aquatic weed." Revista Mexicana de Biodiversidad 79(1): 265-269. 

8.05

Don't know


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