Thunbergia grandiflora (Roxb. ex Rottl.) Roxb., Acanthaceae

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Present on Pacific Islands?  yes

Primarily a threat at high elevations?  no

Risk assessment results: 

Reject, score: 13 (Go to the risk assessment (Australia))
High risk, score: 11 (Go to the risk assessment (Pacific))

Common name(s): [more details]

English: Bengal clock vine, Bengal trumpet, blue trumpet vine, large-flowered thunbergia, skyflower

French: liane mauve

Palauan: bung el etiu

Pohnpeian: iolen pengkal

Habit:  vine

Description:  "Climbers with broad cordate 5-7-nerved palmately lobed or merely angled leaves to nearly 20 cm long, almost as broad, pubescent, on petioles 4-12 cm long; flowers in pendent racemes, large and showy; calyx pubescent, truncate; corolla violet or whitish, the tube pale yellow, 3-3.5 cm long, 6-8 cm wide across the limb; ovary on a yellowish disk; seeds smooth on one side, warty on the reverse" (Stone, 1970; p. 537). A white-flowered horticultural variety exists.

Habitat/ecology:  Climbing vine. Can smother individual and groups of trees.  "Enshrouds even tall trees and shrubs.  In agricultural areas it infests roadsides and pastures, forming impenetrable thickets"  (Motooka et al., 2003).  "One of Australia's most critical environmental weeds, due to its capacity to rapidly smother rainforest in the tropical lowlands of coastal, north Queensland.  It is a serious threat to the survival of small remnants of lowland tropical rainforest that have been fragmented by agricultural and urban development.  In some areas, T. grandiflora can establish 100 percent ground cover over several hectares, excluding all native plants.  The plant is not known to support any native wildlife and probably provides a refuge for feral pigs.  The plant has the potential to become established throughout lowland rainforest in the world heritage listed 'wet tropics' region of north Queensland, particularly along river/creek banks, along the edges of rainforest and within small rainforest remnants"  (Csurhes & Edwards, 1998; pp. 59-61).

Propagation:  Seeds, cuttings, and fragments of stems and roots. Cultivated as an ornamental and most commonly spread from dumping of garden cuttings. "It grows readily from its tuberous roots that are spread in soil, by water or in garden refuse" (Smith, 2002; p. 53).

Native range:  Asia (northern India).

Presence:

Pacific
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
Cook Islands Southern Cook Islands	Rarotonga Island		Sykes, Bill (year unknown)
Federated States of Micronesia Pohnpei Islands	Pohnpei Island	introduced cultivated	Herrera, Katherine/Lorence, David H./Flynn, Timothy/Balick, Michael J. (2010) (p. 65) Voucher cited: D.H. Lorence 9960 (PTBG) Invasive species.
Fiji Fiji Islands	Mamanuthas Island	introduced invasive cultivated	Smith, Albert C. (1991) (p. 119) Sparingly naturalized.
Fiji Fiji Islands	Vanua Levu Island	introduced invasive cultivated	Smith, Albert C. (1991) (p. 119) Voucher cited: DA 17192 Sparingly naturalized.
Fiji Fiji Islands	Vanua Levu Island		Bishop Museum (Honolulu) (1969) (voucher ID: BISH 36368) Taxon name on voucher: Thunbergia grandiflora (Roxb. ex Rottl.) Roxb.
Fiji Fiji Islands	Viti Levu Island	introduced invasive cultivated	Smith, Albert C. (1991) (p. 119) Voucher cited: Degener 15493 Sparingly naturalized.
Fiji Fiji Islands	Viti Levu Island		Bishop Museum (Honolulu) (1941) (voucher ID: BISH 127886) Taxon name on voucher: Thunbergia grandiflora (Roxb. ex Rottl.) Roxb.
French Polynesia Marquesas Islands	Nuku Hiva (Nukahiva) Island	introduced invasive	Florence, J./Chevillotte, H./Ollier, C./Meyer, J.-Y. (2013) Naturalisée
French Polynesia Society Islands	Moorea Island	introduced invasive	Florence, J./Chevillotte, H./Ollier, C./Meyer, J.-Y. (2013) Naturalisée
French Polynesia Society Islands	Raiatea (Havai) Island	introduced invasive	Florence, J./Chevillotte, H./Ollier, C./Meyer, J.-Y. (2013) Naturalisée
French Polynesia Society Islands	Taha‘a Island	introduced cultivated	Welsh, S. L. (1998) (p. 24) Voucher cited: Fosberg 63539
French Polynesia Society Islands	Taha‘a Island	introduced invasive cultivated	Florence, J./Chevillotte, H./Ollier, C./Meyer, J.-Y. (2013) "Cultivée comme ornementale, se naturalise aisément". Vouchers cited: J. Florence 10513 (PAP), F.R. Fosberg 63539 (PAP) Naturalisée
French Polynesia Society Islands	Taha‘a Island		Bishop Museum (Honolulu) (1982) (voucher ID: BISH 599736) Taxon name on voucher: Thunbergia grandiflora (Roxb. ex Rottl.) Roxb.
French Polynesia Society Islands	Taha‘a Island		Bishop Museum (Honolulu) (1990) (voucher ID: BISH 642734) Taxon name on voucher: Thunbergia grandiflora (Roxb. ex Rottl.) Roxb.
French Polynesia Society Islands	Taha‘a Island		Bishop Museum (Honolulu) (1990) (voucher ID: BISH 644085) Taxon name on voucher: Thunbergia grandiflora (Roxb. ex Rottl.) Roxb.
French Polynesia Society Islands	Taha‘a Island		Bishop Museum (Honolulu) (1982) (voucher ID: BISH 1002073) Taxon name on voucher: Thunbergia grandiflora (Roxb. ex Rottl.) Roxb.
French Polynesia Society Islands	Tahiti Island	introduced	Meyer, Jean-Yves (2000) (p. 94) "Potential invader".
French Polynesia Society Islands	Tahiti Island	introduced cultivated	Welsh, S. L. (1998) (p. 24) Voucher cited: BRY 24799
French Polynesia Society Islands	Tahiti Island	introduced invasive cultivated	Florence, J./Chevillotte, H./Ollier, C./Meyer, J.-Y. (2013) "Ornementale, se naturalise autour des habitations". Voucher cited: J. Florence 2857 (PAP) Naturalisée
French Polynesia Austral (Tubuai) Islands	Raivavae (Raevavae) Island	introduced invasive cultivated	Florence, J./Chevillotte, H./Ollier, C./Meyer, J.-Y. (2013) "Ornementale se naturalisant assez facilement". Voucher cited: J. Florence & W.R. Sykes 11193 (PAP) Naturalisée
French Polynesia Austral (Tubuai) Islands	Raivavae (Raevavae) Island		Bishop Museum (Honolulu) (1992) (voucher ID: BISH 644119) Taxon name on voucher: Thunbergia grandiflora (Roxb. ex Rottl.) Roxb.
French Polynesia Austral (Tubuai) Islands	Rurutu Island	introduced invasive cultivated	Florence, J./Chevillotte, H./Ollier, C./Meyer, J.-Y. (2013) Voucher cited: J. Florence 6212 (PAP) Naturalisée
French Polynesia Austral (Tubuai) Islands	Rurutu Island		Bishop Museum (Honolulu) (1983) (voucher ID: BISH 552805) Taxon name on voucher: Thunbergia grandiflora (Roxb. ex Rottl.) Roxb.
French Polynesia Austral (Tubuai) Islands	Tubuai Island	introduced invasive	Florence, J./Chevillotte, H./Ollier, C./Meyer, J.-Y. (2013) Naturalisée
Guam Guam Island	Guam Island	introduced cultivated	Stone, Benjamin C. (1970) (p. 537) Voucher cited: Stone 4270 (GUAM)
Guam Guam Island	Guam Island	introduced	Fosberg, F. R./Sachet, Marie-Hélène/Oliver, Royce (1979) (p. 260)
Guam Guam Island	Guam Island		Bishop Museum (Honolulu) (1954) (voucher ID: BISH 127890) Taxon name on voucher: Thunbergia grandiflora (Roxb. ex Rottl.) Roxb.
Guam Guam Island	Guam Island		Bishop Museum (Honolulu) (1962) (voucher ID: BISH 127891) Taxon name on voucher: Thunbergia grandiflora (Roxb. ex Rottl.) Roxb.
Guam Guam Island	Guam Island		Bishop Museum (Honolulu) (1954) (voucher ID: BISH 127892) Taxon name on voucher: Thunbergia grandiflora (Roxb. ex Rottl.) Roxb.
Guam Guam Island	Guam Island		Bishop Museum (Honolulu) (1966) (voucher ID: BISH 420296) Taxon name on voucher: Thunbergia grandiflora (Roxb. ex Rottl.) Roxb.
Guam Guam Island	Guam Island		Bishop Museum (Honolulu) (1981) (voucher ID: BISH 443824) Taxon name on voucher: Thunbergia grandiflora (Roxb. ex Rottl.) Roxb.
Guam Guam Island	Guam Island		Bishop Museum (Honolulu) (1980) (voucher ID: BISH 505168) Taxon name on voucher: Thunbergia grandiflora (Roxb. ex Rottl.) Roxb.
State of Hawaii Hawaiian Islands	Hawai‘i (Big) Island	introduced invasive cultivated	Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. (1999) (p. 175)
State of Hawaii Hawaiian Islands	Kaua‘i Island	introduced invasive cultivated	Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. (1999) (p. 175)
State of Hawaii Hawaiian Islands	Maui Island	introduced invasive	Starr, Forest/Martz, Kim/Loope, Lloyd L. (2002) (p. 17) East Maui. Voucher cited: Starr & Martz 980408-130 (BISH)
State of Hawaii Hawaiian Islands	O‘ahu Island	introduced invasive cultivated	Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. (1999) (p. 175) Voucher cited: St. John 18400 (BISH)
Nauru Nauru Island	Nauru Island	introduced cultivated	Thaman, R. R./Fosberg, F. R./Manner, H. I./Hassall, D. C. (1994) (p. 83) Voucher cited: Hassall 187 (SUVA)
New Caledonia New Caledonia Archipelago	Île Grande Terre	introduced cultivated	MacKee, H. S. (1994) (p. 9) Voucher cited: MacKee 20663
Palau Kayangel Atoll	Kayangel Islet	introduced invasive cultivated	Miles, Joel (2015) (p. 2) ref states "Cultivated"
Palau Palau (Belau ) (main island group)	Babeldaob Island	introduced invasive	Space, James C./Waterhouse, Barbara/Miles, Joel E./Tiobech, Joseph/Rengulbai, Kashgar (2003) (pp. 10, 86)
Palau Palau (Belau ) (main island group)	Kayangel (Ngcheangel) Island	introduced invasive	Space, James C./Waterhouse, Barbara/Miles, Joel E./Tiobech, Joseph/Rengulbai, Kashgar (2003) (pp. 10, 89)
Palau Palau (Belau ) (main island group)	Koror (Oreor) Island	introduced	Fosberg, F. R./Sachet, Marie-Hélène/Oliver, Royce (1979) (p. 260)
Palau Palau (Belau ) (main island group)	Koror (Oreor) Island	introduced invasive	Space, James C./Waterhouse, Barbara/Miles, Joel E./Tiobech, Joseph/Rengulbai, Kashgar (2003) (pp. 10, 83)
Palau Palau (Belau ) (main island group)	Koror (Oreor) Island	introduced invasive cultivated	Space, James C./Lorence, David H./LaRosa, Anne Marie (2009) (p. 12)
Palau Palau (Belau ) (main island group)	Koror (Oreor) Island		Bishop Museum (Honolulu) (1968) (voucher ID: BISH 420279) Taxon name on voucher: Thunbergia grandiflora (Roxb. ex Rottl.) Roxb.
Palau Palau (Belau ) (main island group)	Koror (Oreor) Island		Bishop Museum (Honolulu) (1966) (voucher ID: BISH 420295) Taxon name on voucher: Thunbergia grandiflora (Roxb. ex Rottl.) Roxb.
Palau Palau (Belau ) (main island group)	Koror (Oreor) Island		Bishop Museum (Honolulu) (1968) (voucher ID: BISH 571578) Taxon name on voucher: Thunbergia grandiflora (Roxb. ex Rottl.) Roxb.
Palau Palau (Belau ) (main island group)	Koror (Oreor) Island		Beleu National Museum (Republic of Palau. Koror.) (1966) (voucher ID: BNM 59) Taxon name on voucher: Thunbergia grandiflora (Roxb. ex Rosse)
Palau Palau (Belau ) (main island group)	Koror (Oreor) Island		Beleu National Museum (Republic of Palau. Koror.) (1970) (voucher ID: BNM 60) Taxon name on voucher: Thunbergia grandiflora (Roxb. ex Rosse)
Palau Palau (Belau ) (main island group)	Malakal (Ngemelachel) Island	introduced invasive cultivated	Space, James C./Lorence, David H./LaRosa, Anne Marie (2009) (p. 12) Voucher: Lorence 9716 (PTBG, BNM, NY, US, BISH)
Palau Palau (Belau ) (main island group)	Malakal (Ngemelachel) Island		National Tropical Botanical Garden (U.S.A. Hawaii. Kalaheo.) (2008) (voucher ID: PTBG 9) Taxon name on voucher: Thunbergia grandiflora Roxb.
Philippines Philippine Islands	Philippine Islands	introduced cultivated	Merrill, Elmer D. (1923) (p. 469) Commonly planted for ornamental purposes; never observed in fruit.
Samoa Western Samoa Islands	Upolu Island	introduced invasive	Space, James C./Flynn, Tim (2002) (p. 68)
Solomon Islands Solomon Islands	Solomon Islands	introduced cultivated	Hancock, I. R./Henderson, C. P. (1988) (p. 114)

Pacific Rim
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
Australia Australia (continental)	New South Wales	introduced cultivated	Csurhes, S./Edwards, R. (1998) (pp. 59-61)
Australia Australia (continental)	Northern Territory	introduced cultivated	Csurhes, S./Edwards, R. (1998) (pp. 59-61)
Australia Australia (continental)	Northern Territory	introduced invasive	Meyer, Jean-Yves/Lavergne, Christophe (2004) (p. 337)
Australia Australia (continental)	Queensland	introduced invasive cultivated	Csurhes, S./Edwards, R. (1998) (pp. 59-61)
Central America Central America (Pacific rim)	Costa Rica (Republic of)	introduced invasive cultivated	Csurhes, S./Edwards, R. (1998) (pp. 59-61)
China China	Hong Kong	introduced cultivated	Wu, Te-lin (2001) (p. 255) Ornamental.
Singapore Singapore	Singapore (Republic of)	introduced invasive	Pallawatta, Nirmalie/Reaser, Jamie K./Gutierrez, Alixis T./eds. (2003) (p. 89)
Singapore Singapore	Singapore (Republic of)	introduced invasive	Meyer, Jean-Yves/Lavergne, Christophe (2004) (p. 337)
Singapore Singapore	Singapore (Republic of)	introduced invasive	Chong, Kwek Yan/Tan, Hugh T. W./Corlett, Richard T. (2009) (p. 86) Casual

Indian Ocean
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
La Réunion (France) La Réunion Island	La Réunion Island	introduced invasive cultivated	Lavergne, Christophe (2006) "Cultivé/±envahissant"
La Réunion (France) La Réunion Island	La Réunion Island	introduced invasive	Meyer, Jean-Yves/Lavergne, Christophe (2004) (pp. 337, 350)
Mauritius Mautitius Islands (Mauritius and Rodrigues)	Mauritius Island	introduced invasive	Meyer, Jean-Yves/Lavergne, Christophe (2004) (pp. 347, 350)
Seychelles Seychelles Islands	Seychelles Islands	introduced	Weber, Ewald (2003) (p. 433)
Seychelles Seychelles Islands	Seychelles Islands	introduced cultivated	Meyer, Jean-Yves/Lavergne, Christophe (2004) (pp. 337, 350)
Seychelles Seychelles Islands	Seychelles Islands	introduced	Invasive Species Specialist Group (2017)

Comments:  A problem species in Australia (a declared noxious weed in Queensland and a prohibited entrant in Western Australia and the Northern Territory) and Singapore (Smith, 2002; p. 53). Very aggressive in Palau (Space et al., 2003).

Control:  The plant forms large underground tubers and is difficult to eradicate because of regeneration from tubers and root and stem fragments (Csurhes & Edwards, 1998; pp. 59-61). 

Physical:  "Pulling plants and harvesting underground tubers can be effective over time, but is very labor-intensive because all material must be removed or it will re-sprout"  (Englberger, 2009; p. 9).

Chemical: Spraying or painting cut stumps with herbicides such as glyphosate is most effective. "An effective herbicide is imazapyr applied to the foliage during active growth"  (Weber, 2003; p. 433).  "Foliar applications probably impractical because of risk to non-target hosts.  Work needed on treating the foliage and stems on the ground.  Aerial growth may be killed with 2,4-D or or glyphosate but plants resprout from tubers.  In cut-stump treatments, 2,4-D in kerosene with surfactant was effective in Australia.  Triclopyr also appears promising in trials"  (Motooka et al., 2003).

"Triclopyr (Garlon 4) or glyphosate (Roundup) can be used as a foliar spray"  (Englberger, 2009; p. 9).