Research directed by C. Daehler (UH Botany) with funding from the Kaulunani Urban Forestry Program and US Forest Service

Information on Risk Assessments
Original risk assessment

Wedelia trilobata (Thelechitonia trilobata, wedelia, creeping oxeye, Singapore daisy)

Answer

1.01

Is the species highly domesticated?

y=-3, n=0

n

1.02

Has the species become naturalized where grown?

y=-1, n=-1

y

1.03

Does the species have weedy races?

y=-1, n=-1

n

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

n

2.04

Native or naturalized in regions with tropical or subtropical climates

y=1, n=0

y

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

3.02

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

n=0

n

3.03

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

n=0

n

3.04

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

n=0

y

3.05

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

n=0

n

4.01

Produces spines, thorns or burrs

y=1, n=0

n

4.02

Allelopathic

y=1, n=0

n

4.03

Parasitic

y=1, n=0

n

4.04

Unpalatable to grazing animals

y=1, n=-1

4.05

Toxic to animals

y=1, n=0

y

4.06

Host for recognized pests and pathogens

y=1, n=0

n

4.07

Causes allergies or is otherwise toxic to humans

y=1, n=0

n

4.08

Creates a fire hazard in natural ecosystems

y=1, n=0

n

4.09

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

y=1, n=0

y

4.1

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

y=1, n=0

y

4.11

Climbing or smothering growth habit

y=1, n=0

y

4.12

Forms dense thickets

y=1, n=0

n

5.01

Aquatic

y=5, n=0

n

5.02

Grass

y=1, n=0

n

5.03

Nitrogen fixing woody plant

y=1, n=0

n

5.04

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

y=1, n=0

y

6.01

Evidence of substantial reproductive failure in native habitat

y=1, n=0

n

6.02

Produces viable seed.

y=1, n=-1

y

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

n

6.06

Reproduction by vegetative fragmentation

y=1, n=-1

y

6.07

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

See left

7.01

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

y=1, n=-1

y

7.02

Propagules dispersed intentionally by people

y=1, n=-1

y

7.03

Propagules likely to disperse as a produce contaminant

y=1, n=-1

n

7.04

Propagules adapted to wind dispersal

y=1, n=-1

y

7.05

Propagules water dispersed

y=1, n=-1

n

7.06

Propagules bird dispersed

y=1, n=-1

n

7.07

Propagules dispersed by other animals (externally)

y=1, n=-1

n

7.08

Propagules survive passage through the gut

y=1, n=-1

8.01

Prolific seed production (>1000/m2)

y=1, n=-1

n

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

y

8.04

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

y=1, n=-1

y

8.05

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

y=-1, n=1

n

Total score:

13

Source

Notes

1.01

No evidence

1.02

Naturalized in Hawaii.

Wagner,W. L., D. R. Herbst & S. H. Sohmer. 1990. Manual of flowering plants of Hawaii.University of Hawaii at Press. Honolulu.

1.03

No evidence

2.01

(1)Native to Southern Florida and tropical America. 2)NOT native to Florida, native to central/south america

(1)Horticopia: Tress, Shrubs and Groundcover. CD-ROM database. 2)http://turfscience.com/weeds/wedelia.html

2.02

2.03

(1)Hardiness range 8B-11 2)thrives in coastal areas

(1)Horticopia: Tress, Shrubs and Groundcover. CD-ROM database. 2)http://www.bulimbacreek.org.au/Waterwatch/waterwatch5.htm

2.04

(1) tropical America.

(1)Horticopia: Tress, Shrubs and Groundcover. CD-ROM database.

2.05

Has been introduced to several islands in the Pacific and to Australia and Christmas Island.

http://www.hear.org/pier3/wetri.htm

3.01

Naturalized in Hawaii.

Wagner,W. L., D. R. Herbst & S. H. Sohmer. 1990. Manual of flowering plants of Hawaii.University of Hawaii at Press. Honolulu.

3.02

No evidence

3.03

'A noxious weed in agricultural areas, along roadsides and trails, in open lots, waste places and garbage dumps and other disturbed sites.' Not listed as agriculture weed in Holm et al. Geographic Atlas of World Weeds. Cannot find any evidence to confirm that this is a pest/controlled for in agricultural crops/pastures. It is always described as an environmental weed.

http://www.hear.org/pier3/wetri.htm

3.04

(1)'Also naturalized and invasive along streams, canals, along the borders of mangroves and in coastal strang vegetation. (Thaman, 1999) Forms a dense ground cover, crowding out or preventing regeneration of other species. ' (2) 'This species has been nominated as among 100 of the "World's Worst" invaders.' 'This creeping herb native to Central America forms a dense ground cover, crowding out or preventing regeneration of other species.' 3)Category II invader in Florida (need more information) 4)Category 1 in KwaZulu Natal Category 3 in therest of South Africa 5)Targeted for control on Austalian floodplain 

(1)http://www.hear.org/pier3/wetri.htm (2)http://www.issg.org/database/species/ecology.asp?si=44&fr=1&sts=sss 3)http://fleppc.org/01list.htm 4)http://www.weedwarriors.co.za/Pests7.html 5)http://savanna.ntu.edu.au/information/r4/t2/r4_t2_2.html

3.05

No evidence

4.01

No thorns.

Horticopia: Tress, Shrubs and Groundcover. CD-ROM database.

4.02

No evidence

4.03

No evidence

4.04

No information

4.05

Farm animals have aborted fetuses after grazing on Wedelia

http://www.floridata.com/ref/w/wedelia.cfm

4.06

No evidence

4.07

No evidence

4.08

unlikely -- must be dried to burn

http://www.bulimbacreek.org.au/Waterwatch/waterwatch5.htm

4.09

Partial shade to full sun. 'Producing the most bloom in full sun, frost free locations, wedelia will grow in shade still bloom, although sparsely.'

Horticopia: Tress, Shrubs and Groundcover. CD-ROM database.

4.1

Clay, Sandy, Loam and well drained soil.

Horticopia: Tress, Shrubs and Groundcover. CD-ROM database.

4.11

(1)'Creating a dense mat of foliage wedelia rarely needs pruning …' (2)Prostrate growth habit. (3)Forms a dense ground cover, crowding out or preventing regeneration of other species.

(1)Horticopia: Tress, Shrubs and Groundcover. CD-ROM database. (2)Plant master CD-ROM database. (3)http://www.hear.org/pier3/wetri.htm

4.12

5.01

Perennial herbaceous prostrate plant in Astereceae

http://plants.usda.gov/cgi_bin/topics.cgi

5.02

5.03

5.04

bulbous roots

6.01

No evidence

6.02

easily propagate it by seed.

http://www.emilycompost.com/wedelia.htm

6.03

No information

6.04

No information

6.05

Probably not - the flower morphology does not appear to be adapted for specialized pollination.

Horticopia A to Z. CD-ROM database.

6.06

(1) '…the long creeping stems rooting wherever they touch moist soil.' (2)'Usually vegetatively. Stems form new plants where they touch the ground and pieces readily take root. '

(1)Horticopia: Tress, Shrubs and Groundcover. CD-ROM database. (2)http://www.hear.org/pier3/wetri.htm

6.07

Fast growing. No direct evidence.

Horticopia: Tress, Shrubs and Groundcover. CD-ROM database.

7.01

'Stems form new plants where they touch the ground and pieces readily take root. Commonly spread by dumping of garden waste'

http://www.hear.org/pier3/wetri.htm

7.02

Attractive flowers or blooms.

Horticopia A to Z. CD-ROM database.

7.03

Probably not - seeds relatively long. (1)Achenes tuberculate, 4-5 mm long.

(1)Wagner,W. L., D. R. Herbst & S. H. Sohmer. 1990. Manual of flowering plants of Hawaii.University of Hawaii at Press. Honolulu.

7.04

1)Probably yes - achenes with pappus. 2)seed is dispersed by the wind

1)Wagner,W. L., D. R. Herbst & S. H. Sohmer. 1990. Manual of flowering plants of Hawaii.University of Hawaii at Press. Honolulu. 2)http://www.bulimbacreek.org.au/Waterwatch/waterwatch5.htm

7.05

7.06

7.07

Propagules have no means of attachment.

7.08

No information

8.01

Achenes tuberculate, 4-5 mm long. In Hawaii few achenes mature in cultivated plants.

Wagner,W. L., D. R. Herbst & S. H. Sohmer. 1990. Manual of flowering plants of Hawaii.University of Hawaii at Press. Honolulu.

8.02

No information regarding seed survival.

8.03

1) "Here in Queensland, Australia Wedelia has become a widespread problem plant. A metsulfuron methyl herbicide (600g/kg) has been registered for spraying the weed. The mixing rate is 10g/100L of water plus a surfactant. This gives good control, but it is important to follow-up with touch up treatments to pick up the underground stems which were missed first time round." (Greg Brown, Queensland Department of Natural Resources, communications to Aliens listserver). 2)Treat small patches with 2% Roundup; large, dense populations may be treated by broadcast-spraying 5% Roundup (with follow-up treatments as needed). Or 1/4-1.0% Garlon 4 in water.

1) http://www.hear.org/pier3/wetri.htm 2)http://edis.ifas.ufl.edu/BODY_WG209

8.04

'Though killed to the ground by frost, wedelia's rapid growth quickly returns with warm weather…' '…can withstand severe trimming.'

Horticopia: Tress, Shrubs and Groundcover. CD-ROM database.

8.05

Has spread widely in natural areas of Hawai‘i.