Pacific Island Ecosystems at Risk (PIER)


Pilea nummulariifolia


RISK ASSESSMENT RESULTS: Low risk, score: 0


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

Pilea nummulariifolia (Swartz) Weddell. Family - Urticaceae. Common Names(s) - creeping Charlie. Synonym(s) - Urtica nummularifolia Sw.

Answer

Score

1.01

Is the species highly domesticated?

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

3.01

Naturalized beyond native range y = 1*multiplier (see Append 2), n= question 2.05

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)

n

0

3.05

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

y

2

4.01

Produces spines, thorns or burrs

n

0

4.02

Allelopathic

n

0

4.03

Parasitic

n

0

4.04

Unpalatable to grazing animals

n

-1

4.05

Toxic to animals

4.06

Host for recognized pests and pathogens

n

0

4.07

Causes allergies or is otherwise toxic to humans

n

0

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

y

1

4.10

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

y

1

4.11

Climbing or smothering growth habit

n

0

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

n

0

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

1

1

7.01

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

n

-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)

n

-1

8.02

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

n

-1

8.03

Well controlled by herbicides

y

-1

8.04

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

y

1

8.05

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

Total score:

0

Supporting data:

Notes

Source

1.01

No evidence

 

1.02

1.03

2.01

(1)DISTRIBUTION, ETC. Native in tropical S America, from Amazonian Peru to NE South America and the Antilles. (2)The native range of P. nummulariifolia includes the West Indies and Latin America from Panama to Peru.

(1)Friis, I. 1989. A Revision of Pilea (Urticaceae) in Africa. Kew Bulletin 44(4): 557-600.(2)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, HI.

2.02

Native range well known and within tropical areas.

 

2.03

(1)Hardiness:USDA Zone 10a: to -1.1 °C (30 °F)USDA Zone 10b: to 1.7 °C (35 °F)USDA Zone 11: above 4.5 °C (40 °F) (2)Pilea spp "thrive at low elevations where hot, humid conditions prevail; they do not tolerate cold, drought, wind, or salt spray."

(1)http://davesgarden.com/guides/pf/go/69038/ [Accessed 19 May 2008] (2)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, HI.

2.04

(1)DISTRIBUTION, ETC. Native in tropical S America, from Amazonian Peru to NE South America and the Antilles. (2)The native range of P. nummulariifolia includes the West Indies and Latin America from Panama to Peru.

(1)Friis, I. 1989. A Revision of Pilea (Urticaceae) in Africa. Kew Bulletin 44(4): 557-600. (2)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, HI.

2.05

(1)Recorded as introduced in Zaire. (2)COOK ISLANDS STATUS: Introduced - Recent, Not naturalised; Land, lowlands, gardens. (3)Moist, disturbed hammocks. Rare; Palm Beach Co. Native to tropical America. Escaped from cultivation (4)It is cultivated worldwide as an ornamental. (5)Recent introduction. Tropical America. Uncommon. Ornamental groundcover and potted plant at Good Earth Apartments and private gardens [Marshall Islands] (6)Recent introduction. Tropical America. Occasional.[Island of Nauru]

(1)Friis, I. 1989. A Revision of Pilea (Urticaceae) in Africa. Kew Bulletin 44(4): 557-600. (2)McCormack, Gerald (2007) Cook Islands Biodiversity Database, Version 2007.2. Cook Islands Natural Heritage Trust, Rarotonga. Online at http://cookislands.bishopmuseum.org. [Accessed 19 May 2008] (3)http://davesgarden.com/guides/pf/go/69038/ [Accessed 19 May 2008] (4)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, HI. (5)Vander Velde, N. 2003. The Vascular Plants of Majuro Atoll, Republic of the Marshall Islands. Atoll Research Bulletin 501.

3.01

(1)Moist, disturbed hammocks. Rare; Palm Beach Co. Native to tropical America. Escaped from cultivation [insufficient evidence of naturalization] (2)Pilea nummularifolia Griseb. Class: new naturalisation for Australia, previously not recorded Collecting details:Collector: A.R.Bean (Queensland Herbarium) Locality: Jubilee Rd, N of Innisfail. Note: population covering 2 square metres [apparently not widespread]

(1)Wunderlin, R. P. and B. F. Hansen. 2003. Guide to the Vascular Plants of Florida, Second Edition. University of Florida Press. Gainesville, FL. (2)http://www.weeds.crc.org.au/documents/weed_spotters_summer08_newsletter.pdf [Accessed 19 May 2008]

3.02

(1)Remarks: Can become a weed problem [a reference to weediness of plant in home plantings, but no mention of control]

(1)Black, R. J. 2003. Ground Covers for Florida Homes. Available from http://edis.ifas.ufl.edu/pdffiles/EP/EP01600.pdf [Accessed 19 May 2008]

3.03

(1)Listed as a weed of banana and sugar cane crops in Basse Terre, Guadeloupe [paper lists P. nummulariifolia as one of many weeds occurring in banana plantations, but there is no indication that it is reducing yields or is subject to any control efforts]

(1)Fournet, J. 1993. Caractérisation phytoécologique des peuplements de mauvaises herbes des champs de canne à sucre et des bananeraies de la Basse Terre (Guadeloupe) Weed Research 33 (5): 383–395.

3.04

No evidence

3.05

(1)Weeds in nurseries are not only unsightly; they can hinder growth of ornamental crops; increase production costs due to weeding labor or diminish value of containerized plants if not removed, and they can harbor insects or diseases, which may be passed on to the crop. Pilea microphylla (L.) Liebm, commonly called artillery plant, is a creeping herb that thrives under the humid conditions typical of many nursery areas. By freely re-seeding itself, this plant spreads rapidly, and can quickly become a major problem.

(1)Conover, C. A.and R.H. Stamps. Controlling Artillery Plant (Pilea microphylla) with Herbicides. Available from http://mrec.ifas.ufl.edu/foliage/resrpts/rh_94_7.htm [Accessed 19 May 2008]

4.01

(1)No evidence

(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, HI.

4.02

No evidence

4.03

No evidence

4.04

(1)Healthy fresh tortoise foods are in abundance everywhere - you just need to know what to look for. This list is intended to serve as a guide to identifying natural foods, as easy and painlessly as possible [List includes P. nummulariifolia as palatable to tortoises]

(1)http://www.africantortoise.com/edible_landscaping.htm [Accessed 19 May 2008]

4.05

(1)Non-toxic: These plants are not poisonous or there is no known record of toxicity. Exposure to these plants is not expected to cause any symptoms. (2)Non-Toxic Plants for Lizards (3)Plants Poisonous to Cats. Below is a picture of a plant known to be or believed to be poisonous to cats [includes Pilea nummulariifolia without any indication of why plant is believed to be toxic; possibly confused with other toxic Creeping Charlie, aka Glechoma hederacea] (4)Listed as Non-toxic to sugar gliders

(1)http://www.feathered-friends.co.uk/site/content/view/20/#top [Accessed 19 May 2008] (2)http://www.the-lizard-lounge.com/content/library/plants/nontoxic-plants.asp [Accessed 19 May 2008] (3)http://www.purrballs.com/catcare/plants/creepingcharlie.html [Accessed 19 May 2008] (4)http://www.moondance-sugargliders.com/sugar_glider_plant-tree_information.htm [Accessed 19 May 2008]

4.06

(1)Roots affected by Pythium sp. & Rhizoctonia sp. [pathogens with widespread host range] (2)Pilea spp. are impacted by a number of pathogens and invertebrate pests, but there is no indication that they are important vectors of these to important crop or native plants.

(1)http://www.hear.org/pph/hosts/5149.htm [Accessed 19 May 2008] (2)http://mrec.ifas.ufl.edu/Foliage/folnotes/pilea.htm [Accessed 19 May 2008]

4.07

(1)Creeping Charlie—(Pilea nummularifolia) non-toxic.

(1)http://lancaster.unl.edu/factsheets/031.htm [Accessed 19 May 2008]

4.08

Succulent plant of moist sites

 

4.09

(1)Creeping-Charlie is a fast-growing plant that requires ample moisture and a shady situation. (2)Pilea nummulariifolia (Sw.) Wedd.; occasional to locally common, moist shaded banks

(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, HI.(2)Acevedo-Rodriguez, P. and F. S. Axelrod. 1999. Annotated Checklist for the Tracheophytes of Rı´o Abajo Forest Reserve, Puerto Rico. Caribbean Journal of Science 35(3-4): 265-285.

4.10

(1)Soil pH requirements:6.1 to 6.5 (mildly acidic)6.6 to 7.5 (neutral)7.6 to 7.8 (mildly alkaline)

(1)http://davesgarden.com/guides/pf/go/69038/ [Accessed 19 May 2008]

4.11

(1)Creeping herb

(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, HI.

4.12

(1)A low, creeping perennial growing to 8 inches high, this species from Peru, Panama, and the West Indies roots at each node, forming a thick mat. [possibly suppresses other vegetation, but low-growth unlikely to impede movement]

(1)Rauch, F. D. Paul and R. Weissich. 2000. Plants for Tropical Landscapes: A Gardener's Guide. University of Hawaii Press. Honolulu, HI.

5.01

Terrestrial

5.02

Urticaceae

5.03

Urticaceae

5.04

No evidence

6.01

(1)No evidence (produces achenes in Panama]

(1)Killip, E. P. 1960. Urticaceae. Pp 179-198 in L. I. Nevling, Jr. Flora of Panama. Part IV. Fascicle II. Annals of the Missouri Botanical Garden 47(2): 81-203.

6.02

(1)Achene c. 0-5 mm long, compressed ovoid, brown, smooth [apparently yes although most propagation methods refer to cuttings] (2)achenes barely 0.4 mm long.

(1)Friis, I. 1989. A Revision of Pilea (Urticaceae) in Africa. Kew Bulletin 44(4): 557-600. (2)Killip, E. P. 1960. Urticaceae. Pp 179-198 in L. I. Nevling, Jr. Flora of Panama. Part IV. Fascicle II. Annals of the Missouri Botanical Garden 47(2): 81-203.

6.03

Unknown

6.04

(1)plants dioecious or occasionally monoecious [unknown whether monoecious plants are self-compatible] (2)flowers are inconspicuous, many, unisexual...

(1)Killip, E. P. 1960. Urticaceae. Pp 179-198 in L. I. Nevling, Jr. Flora of Panama. Part IV. Fascicle II. Annals of the Missouri Botanical Garden 47(2): 81-203.(2)Whistler, W. A. 2000. Tropical Ornamentals, A Guide. Timber Press. Portland, OR.

6.05

(1)Pollination Syndromes - Wind pollination (anemophily)

(1)http://florawww.eeb.uconn.edu/pol_wind.html [Accessed 20 May 2008]

6.06

(1)Creeping herb, rooting freely from nodes.

(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, HI.

6.07

(1)rooting freely from nodes…Creeping-Charlie is a fast-growing plant [plant can spread rapidly through vegetative means] (2)Flowers anytime during the year

(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, HI. (2)Whistler, W. A. 2000. Tropical Ornamentals, A Guide. Timber Press. Portland, OR.

7.01

No evidence [small seeds, when produced, have no mechanism for attachment, although possible they could adhere to shoes, tires, etc. in mud]

 

7.02

(1)It is cultivated worldwide as an ornamental.

(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, HI.

7.03

No evidence, despite popularity as ornamental plant.

 

7.04

(1)achenes barely 0.4 mm long.[no adaptations for wind dispersal]

(1)Killip, E. P. 1960. Urticaceae. Pp 179-198 in L. I. Nevling, Jr. Flora of Panama. Part IV. Fascicle II. Annals of the Missouri Botanical Garden 47(2): 81-203.

7.05

No evidence [small seed size suggests possible ability to be water dispersed, but references outside native range only mention vegetative spread of species]

 

7.06

(1)achenes barely 0.4 mm long [no evidence that Pilea seeds are dispersed by birds]

(1)Killip, E. P. 1960. Urticaceae. Pp 179-198 in L. I. Nevling, Jr. Flora of Panama. Part IV. Fascicle II. Annals of the Missouri Botanical Garden 47(2): 81-203.

7.07

No mechanism for attachment [small seed size suggests possible ability to be carried in mud on hooves/feet/fur of animals, but references outside native range only mention vegetative propagation/spread of species]

 

7.08

Unknown

8.01

(1)Propagate by cuttings, the technique most used. [although evidence of seed production exists from native range, horticultural references consistently mention propagation by cuttings and vegetative spread of species]

(1)Whistler, W. A. 2000. Tropical Ornamentals, A Guide. Timber Press. Portland, OR.

8.02

No evidence [unlikely that seed bank is formed as references outside native range only mention vegetative spread of species]

 

8.03

(1)In both experiments, best results were obtained from Ronstar® 50 WP (Tables 2 through 5). Artillery plants growing in full sun or 60% shade were almost dead two weeks after Ronstar was applied and no new growth had appeared eight weeks after plants were sprayed. Two weeks after spraying, artillery plant treated with Roundup exhibited significant phytotoxic symptoms. However, eight weeks after treatments were made, seed germination and plant regrowth had occurred in Roundup® sprayed containers and artillery plant was covering nearly 50% of the growing medium surface in containers under full sun or 60% shade. [Refers to control of related species P. microphylla, but similarity in morphology and habit suggests that P. nummulariifolia would be similarly susceptible to herbicides]

(1)http://mrec.ifas.ufl.edu/foliage/resrpts/rh_94_7.htm [Accessed 20 May 2008]

8.04

(1)Creeping herb, rooting freely from nodes [every fragment with a node can root to form a new plant]

(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, HI.

8.05

Unknown


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