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

Thunbergia grandiflora Roxb. (Bengal clock vine, Bengal trumpet, blue skyflower, blue trumpet vine) synonyms: T. lacei and T. clarkei

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

y

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

y

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

n

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

y

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

2

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

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

n

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

Total score:

11

Notes

Source

1.01

no evidence

1.02

Distributional range:
Native:
ASIA-TROPICAL
Indian Subcontinent: Bhutan; India [n.e.]; Nepal
Indo-China: Myanmar
Other: cultivated & sometimes naturalized elsewhere

USDA, ARS, National Genetic Resources Program.
Germplasm Resources Information Network - (GRIN) [Online Database].
National Germplasm Resources Laboratory, Beltsville, Maryland.
URL: http://www.ars-grin.gov/var/apache/cgi-bin/npgs/html/tax_search.pl?Thunbergia+grandiflora (11 September 2004)

1.03

no evidence

2.01

Distributional range:
Native:
ASIA-TROPICAL
Indian Subcontinent: Bhutan; India [n.e.]; Nepal
Indo-China: Myanmar
Other: cultivated & sometimes naturalized elsewhere

USDA, ARS, National Genetic Resources Program.
Germplasm Resources Information Network - (GRIN) [Online Database].
National Germplasm Resources Laboratory, Beltsville, Maryland.
URL: http://www.ars-grin.gov/var/apache/cgi-bin/npgs/html/tax_search.pl?Thunbergia+grandiflora (11 September 2004)

2.02

2.03

(1)Hardiness Range 9B to 11 (2)rainforest habitat (3)Specimens from sea level to 1600 m (4)This Thunbergia species does very well in the Coastal region of South Carolina and has survived temperatures as low as 15 F.

(1)Horticopia A-Z.Horticopia, Inc., Purcellville, VA. ISBN 1-887215-07-7. (2)http://farrer.riv.csu.edu.au/ASGAP/APOL16/dec99-2.html (3)http://mobot.mobot.org/cgi-bin/search_vast (4)http://davesgarden.com/pdb/go/1968/index.html

2.04

Distributional range:
Native:
ASIA-TROPICAL
Indian Subcontinent: Bhutan; India [n.e.]; Nepal
Indo-China: Myanmar
Other: cultivated & sometimes naturalized elsewhere

USDA, ARS, National Genetic Resources Program.
Germplasm Resources Information Network - (GRIN) [Online Database].
National Germplasm Resources Laboratory, Beltsville, Maryland.
URL: http://www.ars-grin.gov/var/apache/cgi-bin/npgs/html/tax_search.pl?Thunbergia+grandiflora (11 September 2004)

2.05

Distribution in US: Florida, Hawaii, Puerto Rico

USDA, NRCS. 2004. The PLANTS Database, Version 3.5 (http://plants.usda.gov). National Plant Data Center, Baton Rouge, LA 70874-4490 USA.

3.02

no evidence

3.03

no evidence

3.04

(1)"Thunbergia (Thunbergia grandiflora) is destroying north Queensland tropical lowland rain forests at a rate of about 0.5 ha/yr. " (2)Significant environmental weed of Queensland and Northern Territory (Australia)

(1)Haaren, P. van , Vitelli, J. (1997) Chemical control of thunbergia (Thunbergia grandiflora). Plant Protection Quarterly, 1997, Vol. 12, No. 1, pp. 29-32, 11 ref. (2)RANDALL, R. 2001. Garden thugs, a national list of invasive and potentially invasive garden plants. Plant Protection Quarterly 16: 138-171.

3.05

Thunbergia alata are T. annua are listed as common and pricipal weeds.

Bacon, P., P.J. Terry, N. Waltham, & P.Castro S. (1997) An Electronic Atlas of World Weed and Invasive Plants. Version 1.0, 1997. A database based on the original work "A Geographical Atlas of World Weeds" by Holm et al 1979.

4.01

no description of these traits

http://www.hear.org/pier/species/thunbergia_grandiflora.htm

4.02

no evidence

4.03

no evidence

4.04

don't know

4.05

no evidence

4.06

no evidence

4.07

no evidence

4.08

rainforest plant

http://farrer.riv.csu.edu.au/ASGAP/APOL16/dec99-2.html

4.09

(1)Exposure: Partial shade or partial sun to full sun (2)It is one of the most free flowering vines for shade (3)mine is flowering inside [can be grown indoors]

(1)Horticopia A-Z.Horticopia, Inc., Purcellville, VA. ISBN 1-887215-07-7. (2)http://davesgarden.com/pdb/go/1968/index.html (3)http://davesgarden.com/pdb/go/1968/index.html

4.1

Soil Condition Loamy, sandy, clay, acidic, neutral, alkaline, tolerates salt, somewhat drought tolerant

Horticopia A-Z.Horticopia, Inc., Purcellville, VA. ISBN 1-887215-07-7.

4.11

"Habitat/ecology: Climbing vine. Can smother individual and groups of trees."

http://www.hear.org/pier/species/thunbergia_grandiflora.htm

4.12

vine

5.01

vine; Acanthaceae

5.02

vine; Acanthaceae

5.03

vine; Acanthaceae

5.04

vine with tuber

6.01

invade native habitat

http://www.nrm.qld.gov.au/factsheets/pdf/pest/PP23.pdf

6.02

"Propagation: Seeds, cuttings, and fragments of stems and roots. Cultivated as an ornamental and most commonly spread from dumping of garden cuttings."

http://www.hear.org/pier/species/thunbergia_grandiflora.htm

6.03

no evidence

6.04

failed to set seed, possibly because the vines were descended from a single self-incompatible variety

Young, A. M. (1983) Nectar and pollen robbing of Thunbergia grandiflora by Trigona bees in Costa Rica. Biotropica, 1983, Vol. 15, No. 1, pp. 78-80

6.05

(1) AB: "The flowers were visited by the bee Xylocopa latipes; in Thailand another Xylocopa sp. also visited them. The bee has to push through a narrow channel between the stamens to reach the nectar. No nectar robbing was observed, even when ants were excluded. Thus, the results do not support the hypothesis that ants protect flowers from nectar robbing." [Xylocopa species]
(2) AB: Thunbergia grandiflora, grown as an ornamental plant in Central America, failed to set seed, possibly because the vines were descended from a single self-incompatible variety, or because of a lack of pollinating activity by bees. More than 80% of open flowers on vines showed one or both of two types of damage: anthers chewed apart and/or the bulbous area behind the constriction of the corolla with a hole chewed through it to expose the nectar cavity. Almost 100% of all fallen flowers had damaged anthers; 20-80% had corolla damage. At one site T. (Trigona) silvestriana, T. (Trigona) fulviventris fulviventris, T. (Partamona) testace

(1) Fiala, B. , Krebs, A. , Barlow, H. S. , Maschwitz, U. (1996) Interactions between the climber Thunbergia grandiflora, its pollinator Xylocopa latipes and the ant Dolichoderus thoracicus: the "nectar-thief hypothesis" refuted? Malayan Nature Journal, 1996, Vol. 50, No. 1, pp. 1-14
(2) Young, A. M. (1983) Nectar and pollen robbing of Thunbergia grandiflora by Trigona bees in Costa Rica. Biotropica, 1983, Vol. 15, No. 1, pp. 78-80
(3) LEMKE-T-O (1985) POLLEN CARRYING BY THE NECTAR-FEEDING BAT GLOSSOPHAGA-SORICINA IN A SUBURBAN ENVIRONMENT. Biotropica-. 1985; 17(2): 107-111.

6.06

"Propagation: Seeds, cuttings, and fragments of stems and roots. Cultivated as an ornamental and most commonly spread from dumping of garden cuttings."

http://www.hear.org/pier/species/thunbergia_grandiflora.htm

6.07

flowers in first year [after purchasing at a garden shop, so total time >1 year]

http://davesgarden.com/pdb/go/1968/index.html

7.01

"Propagation: Seeds, cuttings, and fragments of stems and roots. Cultivated as an ornamental and most commonly spread from dumping of garden cuttings."

http://www.hear.org/pier/species/thunbergia_grandiflora.htm

7.02

"Propagation: Seeds, cuttings, and fragments of stems and roots. Cultivated as an ornamental and most commonly spread from dumping of garden cuttings."

http://www.hear.org/pier/species/thunbergia_grandiflora.htm

7.03

no evidence

7.04

The seed pod is inconspicuous, cone shaped, 3-5 cm long, with a rounded base. The seed is flat, up to 1 cm long and covered with brown scales. It is catapulted several metres when the ripe pod splits. [not described as wind-dispersed, but seed is flat; don't know if it is winged]

http://www.nrm.qld.gov.au/factsheets/pdf/pest/PP23.pdf

7.05

no evidence

7.06

The seed pod is inconspicuous, cone shaped, 3-5 cm long, with a rounded base. The seed is flat, up to 1 cm long and covered with brown scales. It is catapulted several metres when the ripe pod splits.

http://www.nrm.qld.gov.au/factsheets/pdf/pest/PP23.pdf

7.07

The seed pod is inconspicuous, cone shaped, 3-5 cm long, with a rounded base. The seed is flat, up to 1 cm long and covered with brown scales. It is catapulted several metres when the ripe pod splits.

http://www.nrm.qld.gov.au/factsheets/pdf/pest/PP23.pdf

7.08

no evidence of ingestion

8.01

The seed pod is inconspicuous, cone shaped, 3-5 cm long, with a rounded base. The seed is flat, up to 1 cm long and covered with brown scales. It is catapulted several metres when the ripe pod splits. [probably not, lare seed; generally no seeds produced from cultivated plants]

http://www.nrm.qld.gov.au/factsheets/pdf/pest/PP23.pdf

8.02

no evidence

8.03

(1) AB: Three experiments were conducted near Innisfail, Queensland, during 1987-91, to test 25 herbicides at various concentrations as high volume foliar applications for the control of thunbergia. Most herbicides produced 100% brown out, but failed to prevent regrowth of underground tubers and allowed complete recovery of treated plants in 3-6 months. Only imazapyr (1.87, 2.5 and 3.75 g L-1) killed both the above-ground growth and the tuberous root system. The three next most effective herbicides, triclopyr/picloram, fluroxypyr and 2,4-D/picloram produced 80-100% foliage reduction and 20-75% regrowth of underground tubers. [depends on the herbicides used]
(2) "Chemical treatment is often the only option availableand provides fast and effective control. Arsenal is the only herbicide registered for the control of Thunbergia. It is systemic so when applied as a foliar spray it is transported within the plant to kill the underground tubers. If access can be gained to tubers, it is possible to inject or apply th

(1) Haaren, P. van , Vitelli, J. (1997) Chemical control of thunbergia (Thunbergia grandiflora). Plant Protection Quarterly, 1997, Vol. 12, No. 1, pp. 29-32, 11 ref.
(2) http://www.nrm.qld.gov.au/factsheets/pdf/pest/PP23.pdf

8.04

(1) "Regular pruning is required to keep this plant in bounds." [tolerate heavy pruning]
(2) "The plant develops a very tuberous root system, some tubers being as large as 70 kg. The root system when cut, persistently sprouts from its many dormant buds." [ability to resprout from underground tuber]

(1) http://hort.ifas.ufl.edu/shrubs/THUGRAA.PDF
(2) http://www.nrm.qld.gov.au/factsheets/pdf/pest/PP23.pdf

8.05

no evidence