Pacific Island Ecosystems at Risk (PIER)


Plectranthus prostratus


RISK ASSESSMENT RESULTS: Low risk, score: 5 (low risk based on second screen)


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

Plectranthus prostratus Gurke. Family - Lamiaceae. Synonym(s) - Plectranthus quadridentatus Schweinf. ex Baker.; succulent Swedish ivy, pillow plant

Answer

Score

1.01

Is the species highly domesticated? (If answer is 'no' then go to question 2.01)

n

0

1.02

Has the species become naturalized where grown?

1.03

Does the species have weedy races?

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

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)

n

0

2.04

Native or naturalized in regions with tropical or subtropical climates

y

1

2.05

Does the species have a history of repeated introductions outside its natural range? y=-2

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)

 

3.03

Agricultural/forestry/horticultural weed y = 2*multiplier (see Append 2)

 

3.04

Environmental weed y = 2*multiplier (see Append 2)

 

3.05

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

y

2

4.01

Produces spines, thorns or burrs

n

0

4.02

Allelopathic

4.03

Parasitic

n

0

4.04

Unpalatable to grazing animals

4.05

Toxic to animals

4.06

Host for recognized pests and pathogens

4.07

Causes allergies or is otherwise toxic to humans

4.08

Creates a fire hazard in natural ecosystems

n

0

4.09

Is a shade tolerant plant at some stage of its life cycle

4.1

Tolerates a wide range of soil conditions (or limestone conditions if not a volcanic island)

 

4.11

Climbing or smothering growth habit

y

1

4.12

Forms dense thickets

n

0

5.01

Aquatic

n

0

5.02

Grass

n

0

5.03

Nitrogen fixing woody plant

n

0

5.04

Geophyte (herbaceous with underground storage organs -- bulbs, corms, or tubers)

n

0

6.01

Evidence of substantial reproductive failure in native habitat

6.02

Produces viable seed.

y

1

6.03

Hybridizes naturally

6.04

Self-compatible or apomictic

6.05

Requires specialist pollinators

n

0

6.06

Reproduction by vegetative fragmentation

y

1

6.07

Minimum generative time (years) 1 year = 1, 2 or 3 years = 0, 4+ years = -1

 

7.01

Propagules likely to be dispersed unintentionally (plants growing in heavily trafficked areas)

y

1

7.02

Propagules dispersed intentionally by people

y

1

7.03

Propagules likely to disperse as a produce contaminant

n

-1

7.04

Propagules adapted to wind dispersal

n

-1

7.05

Propagules water dispersed

n

-1

7.06

Propagules bird dispersed

n

-1

7.07

Propagules dispersed by other animals (externally)

n

-1

7.08

Propagules survive passage through the gut

8.01

Prolific seed production (>1000/m2)

8.02

Evidence that a persistent propagule bank is formed (>1 yr)

8.03

Well controlled by herbicides

8.04

Tolerates, or benefits from, mutilation, cultivation, or fire

8.05

Effective natural enemies present locally (e.g. introduced biocontrol agents)

 

Total score:

5

Second Screening

Low risk

Supporting data:

Notes

Reference

1.01

No evidence.

1.02

1.03

2.01

(1)Native to eastern Africa,...This sprawling herb was apparently originally planted in its present location but appears to be naturalizing in the area. It is growing in open Leucaena scrub along with Verbesina, Coccinia, Sida fallax, and Momordica, and forms groundcover masses on thin soil and rocks. (2)On Marianne Island, Seychelles. Rare in scrubland (3)Hardiness: USDA Zone 7b: to -14.9 C (5 F), USDA Zone 8a: to -12.2 C (10 F), USDA Zone 8b: to -9.4 C (15 F), USDA Zone 9a: to -6.6 C (20 F), USDA Zone 9b: to -3.8 C (25 F), USDA Zone 10a: to -1.1 C (30 F)

(1)Staples, G. W., C. T. Imada, and D. R. Herbst. 2002. New Hawaiian plant records for 2000. Bishop Mus. Occas. Pap. 68: 3--18. (2)Hill, M.J. 2002. BIODIVERSITY SURVEYS AND CONSERVATION POTENTIAL OF INNER SEYCHELLES ISLANDS. ATOLL RESEARCH BULLETIN

NO. 495. (3)http://davesgarden.com/guides/pf/go/129854/ [17 Dec 2007]

2.02

(1)Native to eastern Africa,...This sprawling herb was apparently originally planted in its present location but appears to be naturalizing in the area. It is growing in open Leucaena scrub along with Verbesina, Coccinia, Sida fallax, and Momordica, and forms groundcover masses on thin soil and rocks. (2)On Marianne Island, Seychelles. Rare in scrubland (3)Hardiness: USDA Zone 7b: to -14.9 C (5 F), USDA Zone 8a: to -12.2 C (10 F), USDA Zone 8b: to -9.4 C (15 F), USDA Zone 9a: to -6.6 C (20 F), USDA Zone 9b: to -3.8 C (25 F), USDA Zone 10a: to -1.1 C (30 F)

(1)Staples, G. W., C. T. Imada, and D. R. Herbst. 2002. New Hawaiian plant records for 2000. Bishop Mus. Occas. Pap. 68: 3--18. (2)Hill, M.J. 2002. BIODIVERSITY SURVEYS AND CONSERVATION POTENTIAL OF INNER SEYCHELLES ISLANDS. ATOLL RESEARCH BULLETIN

NO. 495. (3)http://davesgarden.com/guides/pf/go/129854/ [17 Dec 2007]

2.03

(1)Hardiness: USDA Zone 7b: to -14.9 C (5 F), USDA Zone 8a: to -12.2 C (10 F), USDA Zone 8b: to -9.4 C (15 F), USDA Zone 9a: to -6.6 C (20 F), USDA Zone 9b: to -3.8 C (25 F), USDA Zone 10a: to -1.1 C (30 F)

(1)http://davesgarden.com/guides/pf/go/129854/ [17 Dec 2007]

2.04

(1)Native to eastern Africa,...This sprawling herb was apparently originally planted in its present location but appears to be naturalizing in the area. It is growing in open Leucaena scrub along with Verbesina, Coccinia, Sida fallax, and Momordica, and forms groundcover masses on thin soil and rocks. (2)On Marianne Island, Seychelles. Rare in scrubland

(1)Staples, G. W., C. T. Imada, and D. R. Herbst. 2002. New Hawaiian plant records for 2000. Bishop Mus. Occas. Pap. 68: 3--18. (2)Hill, M.J. 2002. BIODIVERSITY SURVEYS AND CONSERVATION POTENTIAL OF INNER SEYCHELLES ISLANDS. ATOLL RESEARCH BULLETIN

NO. 495.

2.05

Mentioned on several websites, but little or no evidence of introduction. (2,3)for sale in many temperate areas (Europe and America), generally as an indoor plant grown by succulent enthusiasts

(2)http://www.accentsforhomeandgarden.com/catalog_i7475770.html?catId=292137 (3)http://www.glasshouseworks.com/succ-pr.html

3.01

(1)This sprawling herb was apparently originally planted in its present location but appears to be naturalizing in the area. It is growing in open Leucaena scrub along with Verbesina, Coccinia, Sida fallax, and Momordica, and forms groundcover masses on thin soil and rocks.

(1)Staples, G. W., C. T. Imada, and D. R. Herbst. 2002. New Hawaiian plant records for 2000. Bishop Mus. Occas. Pap. 68: 3--18.

3.02

Unknown

3.03

Unknown

3.04

Unknown

3.05

(1)In ecological terms one of the most serious threats to Auckland's natural environment is the unchecked establishment and spread of invasive weeds which are destroying those few remaining bush remnants still existing throughout Auckland City. On the Isthmus invasive weeds are found in a wide range of situations. In most native bush remnants tree privet has replaced native canopy trees; exotic groundcover species such as wandering Jew, wild ginger and plectranthus more or less exclude native plant regeneration; exotic tree species such as monkeyapple, Chinese privet and ginger are replacing native shrubs in the understorey; and fast-growing climbers like moth plant, climbing asparagus and jasmine smother trees and shrubs from the ground to upper canopy level. Many former areas of native forest have been reduced to tree privet forests - for example Jaggers Bush (Westmere), Ayr Reserve (Newmarket), and Orakei Basin (Orakei). (2)Plectranthus ciliatus...Originally introduced as a trailing pot plant, and still widely grown in gardens and houses. Listed on the National Pest Plant Accord (3)Plectranthus is a vigorous, effective groundcover so effective, in fact, that not even grass can grow through the dense mats that it forms. Thats all very well when it is kept contained in gardens, but when it escapes into bush reserves and wetlands, its another story, and one without a happy ending. Mats of plectranthus make it hard for native plant seedlings to establish, eventually causing a thinning out of the forest areas, which then allows other weeds to invade. As plectranthus doesnt set seed in New Zealand, the only way it escapes from gardens in the first place is through the illegal dumping of garden waste.

(1)http://www.aucklandcity.govt.nz/council/documents/resources/weed/summary.asp [18 Dec 2007] (2)http://www.rnzih.org.nz/pages/plectranthusciliatus.htm [18 Dec 2007] (3)

4.01

(1)It is a succulent, mat-forming herb with decumbent stems that root at the nodes

(1)Staples, G. W., C. T. Imada, and D. R. Herbst. 2002. New Hawaiian plant records for 2000. Bishop Mus. Occas. Pap. 68: 3--18.

4.02

Unknown

4.03

No evidence.

4.04

Unknown, but some species of Plectranthus listed as fodder for livestock, while others listed as unpalatable (1)Often listed in plant catalogues as tropical mints, Plectranthus are very easy to grow. They are readily propagated; grow indoors and out, in sun or shade; are unpalatable to deer, and are pest-and-disease-free.

(1)http://www.gwenshealinggarden.ca/Foliage_Plants.Plectranthus.htm [18 Dec 2007]

4.05

Unknown, but other species of Plectranthus show toxicity. (1)Abstract: The teratogenic potential of Plectranthus fruticosus essential oil was evaluated in Swiss-OF1 mice injected subcutaneously. They received daily 0, 15, 45 or 135 mg/kg body weight on days 6 to 15 of gestation. A slight maternal toxicity, as evidenced by reduced weight gain and some physical alterations, was observed among treated groups compared with controls. Animals were killed and subjected to uterine examination on day 17 of pregnancy. Plectranthus fruticosus essential oil induced both embryo- and feto-toxicity in the three treated groups, as manifested by a statistically significant increase in the numbers of resorbed and malformed fetuses. The observed malformations were predominantly related to the eyes (anophthalmia). (2)Plectranthus barbatus (Kemtoff et al., 2002) and Plectranthus fruticosus (Chamorro et al., 1991; Pages et al., 1998) have embryo- and fetotoxic activities on rodents.

(1)Pages, N., G. Fournier , G. Chamorro and M. Salazar. 2006. Teratogenic effects of Plectranthus fruticosus essential oil in mice. Phytotherapy Research 5(2): 94 - 96. (2)C. W. Lukhoba, M. S.J. Simmondsb and A. J. Paton. 2006. Plectranthus: A review of ethnobotanical uses. Journal of Ethnopharmacology 103 (2006) 124.

4.06

Unknown

4.07

Unknown for P. prostratus, but other species reported to cause allergic reactions. (1)Abstract: This report discusses a case of a 69-year-old woman who developed chronic non-healing leg ulcers after long-term topical use of Plectranthus amboinicus. The ulcer was proven to be allergic contact dermatitis to P. amboinicus by a patch test. The ulcer healed after discontinuation of P. amboinicus. To the best of our knowledge, this is the first reported case of allergic contact dermatitis to P. amboinicus masquerading as chronic leg ulcer.

(1)Shyue-Luen Chang, Ya-Ching Chang, Chin-Hsun Yang, Hong-Shang Hong. 2005. Allergic contact dermatitis to Plectranthus amboinicus masquerading as chronic leg ulcer. Contact Dermatitis 53 (6), 356357.

4.08

Succulent

4.09

(1)Sun Exposure: Sun to Partial Shade, Light Shade

(1)http://davesgarden.com/guides/pf/go/129854/ [17 Dec 2007]

4.1

Unknown

4.11

Probably could suppress recruitment of other plants due to mat-forming habit (1)It is a succulent, mat-forming herb with decumbent stems that root at the nodes;... forms groundcover masses on thin soil and rocks.(2)forms a lime-green mat

(1)Staples, G. W., C. T. Imada, and D. R. Herbst. 2002. New Hawaiian plant records for 2000. Bishop Mus. Occas. Pap. 68: 3--18. (2)http://www.succulentplants.com/plantsforkids.html

4.12

Low-growing, not thicket forming (1)It is a succulent, mat-forming herb with decumbent stems that root at the nodes;... forms groundcover masses on thin soil and rocks.

(1)Staples, G. W., C. T. Imada, and D. R. Herbst. 2002. New Hawaiian plant records for 2000. Bishop Mus. Occas. Pap. 68: 3--18.

5.01

5.02

Lamiaceae

5.03

Lamiaceae

5.04

(1)Not in description

(1)Staples, G.W. and D.R. Herbst. 2005. A Tropical Garden Flora: Plants Cultivated in the Hawaiian Islands and Other Tropical Places. Bishop Museum Press, Honolulu.

6.01

Unknown

6.02

(1)It seeds itself readily and so has the potential to naturalize, and thrives in dry, sunny situations. (2)Seeds for sale, Plectranthus prostratus - 1 packet for 7 Euros , Plectranthus prostratus - 100 seeds for 11 Euros

(1)Staples, G.W. and D.R. Herbst. 2005. A Tropical Garden Flora: Plants Cultivated in the Hawaiian Islands and Other Tropical Places. Bishop Museum Press, Honolulu. (2)http://www.b-and-t-world-seeds.com/cart_print.asp?species=Plectranthus%20prostratus&sref=449496 [18 Dec 2007]

6.03

Unknown

6.04

Unknown

6.05

Members of genus visited by a variety of generalist insect pollinators (1)In summary the documented insect visitors to Plectranthus belong to the families Anthophoridae, Apidae and Megachilidae (Hymenoptera); Syrphidae, Bombyliidae and Conopidae (Diptera) and Sphingidae and other Lepidoptera

(1)Potgieter, C.J., T. J. Edwards , R. M. Miller, and J. Van Staden. 1999. Pollination of seven Plectranthus spp. (Lamiaceae) in southern Natal, South Africa. Plant Syst. Evol. 218:99-112.

6.06

(1)It is a succulent, mat-forming herb with decumbent stems that root at the nodes

(1)Staples, G. W., C. T. Imada, and D. R. Herbst. 2002. New Hawaiian plant records for 2000. Bishop Mus. Occas. Pap. 68: 3--18.

6.07

Unknown

7.01

spreading along hiking trails at Waahila Ridge and Kaaena Point, Oahu [heavily trafficed areas]

7.02

Ornamental (1)P. prostratus has been cultivated in Hawaii as a groundcover and container plant. (2)Plectranthus prostratus displays a profusion of tiny thick lime green leaves forming a mat of foliage..white flowers with a hint of violet..mounding cascading habit

(1)Staples, G. W., C. T. Imada, and D. R. Herbst. 2002. New Hawaiian plant records for 2000. Bishop Mus. Occas. Pap. 68: 3--18. (2)http://www.accentsforhomeandgarden.com/item2289.ctlg [18 Dec 2007]

7.03

No evidence.

7.04

(1)The genus Plectranthus has dry nutlets

(1)Wagner, W.L. D.R. Herbst and S.H. Sohmer. 1999. Manual of the Flowering Plants of Hawai`i. University of Hawaii and Bishop Museum Press, Honolulu.

7.05

(1)The genus Plectranthus has dry nutlets

(1)Wagner, W.L. D.R. Herbst and S.H. Sohmer. 1999. Manual of the Flowering Plants of Hawai`i. University of Hawaii and Bishop Museum Press, Honolulu.

7.06

(1)The genus Plectranthus has dry nutlets

(1)Wagner, W.L. D.R. Herbst and S.H. Sohmer. 1999. Manual of the Flowering Plants of Hawai`i. University of Hawaii and Bishop Museum Press, Honolulu.

7.07

No mechanisms for such dispersal. Other members of genus with similar nutlets (1)Plectranthus ciliatus...Seed dispersal minimal, vegetative spread from vigorous sprawling runners.

7.08

Propagules unlikely to be eaten by animals.

8.01

Unknown

8.02

Unknown

8.03

Unknown

8.04

Unknown

8.05

Unknown


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