Hedychium gardnerianum Ker Gawl., Zingiberaceae

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Present on Pacific Islands?  yes

Primarily a threat at high elevations?  no

Risk assessment results: 

Hawai‘i/Pacific:  High risk, score: 19 (Go to the risk assessment)
Risk assessment from the Government of Queensland, Australia (PDF format).

Common name(s): [more details]

English: Himalayan ginger, Kahili ginger, kāhili ginger, wild ginger, yellow ginger

Fijian: cevuga dromodromo

French: gingembre-douleur, longose, longose de Gardner

Hawaiian: ‘awapuhi kahili, kāhili

Maori (Cook Islands): kōpī

Pohnpeian: sinter weitahta

Habit:  herb

Description:  "Coarse herbs with leafy shoots 1-2 m tall.  Leaves ovate-elliptic, 20-45 cm long, 10-15 cm wide, glabrous or sparsely pubescent along midrib on lower surface, apex short-acuminate, petioles 1-2 cm long, ligules membranous, 1.5-3 cm long, entire or very shallowly 2-lobed, glabrate, sheaths glabrous or glabrate.  Inflorescences erect, cylindrical, 16-30 (-45) cm long, primary bracts widely spaced, ovate-elliptic, spreading or obliquely ascending, enfolding the cincinni, much shorter than the floral tube, 3-5 cm long, glabrous, rachis glabrous, exposed, cincinni 2-flowered; calyx cylindrical, 3-lobed, 3-3.5 cm long; corolla yellow, the tube longer than the primary bract, 5-5.5 cm long, the lobes greenish yellow, linear, 3.5-5 cm long; labellum centrally tinged orange, 2.5-3 cm long; stamen bright reddish orange, far exceeding labellum, ca. 6.5 cm long; lateral staminodes yellow, ca. 3 cm long; ovary glabrous.  Capsules oblong, ca. 1.5 cm long, the valves orange within.  Seed red, 5-6 mm long"  (Wagner et al., 1999; p. 1623).

Habitat/ecology:  "Forests and forest edges, moist places.  This tall herb spreads rapidly and may become dominant over large areas, especially under canopy openings or in cleared areas. It forms dense thickets that penetrate into undisturbed forests and impede the growth and regeneration of native plants.  Seedlings of shrubs and trees are unable to establish in stands of this plant.  Once established, the plant is shade-tolerant and very persistent"  (Weber, 2003; p. 194).  See also H. coronarium and H. flavescens.

The plant grows in wet habitats between sea level and 1,700 m (Smith, 1985; pp. 191-192).  In New Zealand, "spreading on roadsides and damp places, very common about Auckland" (Healy & Edgar, 1980; p. 42).

Propagation:  By stolons where already established. Conspicuous, fleshy, red seeds are dispersed by frugivorous birds as well as man. Even small root fragments will regrow (Smith, 1985; pp. 191-192).

Native range:  India (Himalayas).

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	Mangaia Island	cultivated	McCormack, Gerald (2011)
Cook Islands Southern Cook Islands	Mangaia Island	introduced cultivated	Space, James C./Flynn, Tim (2002) (p. 86)
Cook Islands Southern Cook Islands	Rarotonga Island	cultivated	McCormack, Gerald (2011)
Cook Islands Southern Cook Islands	Rarotonga Island		Bishop Museum (Honolulu) (1990) (voucher ID: BISH 664890) Taxon name on voucher: Hedychium gardnerianum Ker Gawl.
Federated States of Micronesia Pohnpei Islands	Pohnpei Island	introduced	Fosberg, F. R./Sachet, Marie-Hélène/Oliver, Royce (1987) (p. 113)
Federated States of Micronesia Pohnpei Islands	Pohnpei Island	introduced cultivated	Herrera, Katherine/Lorence, David H./Flynn, Timothy/Balick, Michael J. (2010) (p. 63)
Fiji Fiji Islands	Viti Levu Island	introduced cultivated	Smith, Albert C. (1979) (p. 198) Voucher cited: DA 12338
French Polynesia Society Islands	Tahiti Island	introduced	Fosberg, F. R. (1997) (p. 154)
French Polynesia Society Islands	Tahiti Island	introduced cultivated	Florence, J./Chevillotte, H./Ollier, C./Meyer, J.-Y. (2011) Cultivée
State of Hawaii Hawaiian Islands	Hawai‘i (Big) Island	introduced invasive cultivated	Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. (1999) (p. 1623) Voucher cited: Fagerlund & Mitchell 743
State of Hawaii Hawaiian Islands	Kaua‘i Island	introduced invasive cultivated	Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. (1999) (p. 1623)
State of Hawaii Hawaiian Islands	Lāna‘i Island	introduced invasive cultivated	Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. (1999) (p. 1623)
State of Hawaii Hawaiian Islands	Maui Island	introduced invasive cultivated	Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. (1999) (p. 1623)
State of Hawaii Hawaiian Islands	O‘ahu Island	introduced invasive	Staples, George W./Herbst, Derral R./Imada, Clyde T. (2006) (p. 9) Vouchers cited: B. Kennedy et al. 42 (BISH), C. Imada et al. 2004-58 (BISH)
New Caledonia New Caledonia Archipelago	Île Grande Terre	introduced cultivated	MacKee, H. S. (1994) (p. 142) Voucher cited: MacKee 34886

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)	Australia (continental)	introduced	U.S. Dept. Agr., Agr. Res. Serv. (2011)
Australia Australia (continental)	Queensland	introduced invasive	Queensland Herbarium (2002) (p. 4)
China China	Hong Kong	introduced cultivated	Wu, Te-lin (2001) (p. 353) Ornamental.
New Zealand New Zealand	New Zealand (country)	introduced invasive	Healy, A. J./Edgar, E. (1980) (p. 42) Voucher cited: Lloyd (AK 25040)
New Zealand New Zealand	New Zealand (country)	introduced invasive	Owen, S. J. (1997)

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	MacDonald, I. A. W./Thebaud, C./Strahm, W. A./Strasberg, D. (1991) (pp. 51-61)
La Réunion (France) La Réunion Island	La Réunion Island	introduced invasive	Lavergne, Christophe (2006) "Très envahissant"
La Réunion (France) La Réunion Island	La Réunion Island	introduced invasive	Baret, Stephane/Rouget, Mathieu/Richardson, David M./Lavergne, Christophe/Egoh, Benis/Dupont, Joel/Strasberg, Dominique (2006) (p. 758)
Mascarene Islands Mascarene Islands (Mauritius, La Reunion, Rodrigues)	Mascarene Islands	introduced	U.S. Dept. Agr., Agr. Res. Serv. (2011)

Comments:  A major invader of native forests in New Zealand. Also a problem species in South Africa and La Réunion.

Control: 

Physical: Dig out, pull seedlings and regrowth. Do not compost roots.

Chemical: Treat with herbicide. Escort 25 gm/100 l water + 0.1% Pulse; Roundup 2% +0.2% Pulse; Amitrole (Timmins and Mackenzie, 1995; pp. 127-129.

"1. Cut down and paint stump (all year round): cut above pink 'collar' at base and apply or glyphosate (250ml/L) or metsulferon-methyl 600g/kg (1g /L). Leave stems and leaves on site to rot down. 
2. Dig or pull out small plants (all year round). Don't compost, leave on site to rot down or hang rhizomes in trees, as they survive indefinitely. Dispose of rhizomes at a refuse transfer station or by drying out and burning.
3. Spray (all year round): metsulferon-methyl 600g/kg (5g/10L knapsack). Add penetrant in winter. For dense patches keep spray away from roots of vulnerable plants.  Don't replant sprayed sites for 6 months"  (Weedbusters New Zealand).

Biological:  In Hawai‘i, "Anderson and Gardner (1999) have studied a strain of Ralstonia solanacearum (E.F.Smith) Yabuuchi et al. (Bacteria, Pseudomonaceae) that attacks kahili ginger. They expressed considerable optimism that this fungus has the potential to bring about long term control of this pest including the suppression of seedling establishment. The slow-acting nature of this pathogen may be beneficial in that native species will have a chance to recover before weeds overwhelm them. The establishment of the bacterium is somewhat difficult generally requiring physical damage. Nevertheless, the bacterium has been established in some populations in the Islands. Evidence suggests that the density of plants in these areas is declining. Perhaps the most encouraging aspect of this disease is that seeds do not germinate or damp off soon thereafter where the bacterium is present in the soil. EPA approval may be required before the fungus can be broadcast as a biocide. In the meanwhile, use of this pathogen is limited to local application only though experiments on mass culture, optimal dosage, and alternative inoculation techniques are underway. A potential conflict of interest is that it attacks edible ginger (Zingiber officinele Roscoe - Zingiberales, Zingiberaceae). The difficulty of dissemination and establishment of the bacterium suggests that this concern is not a significant problem. The infestations of kahili ginger are well above the areas were ginger is grown commercially"  (Smith et al., 2002; p. 95).

Additional information:
Information on the Environment Bay of Plenty, New Zealand, web site.
Information from the Global Invasive Species Database.
Information sheet from Weedbusters New Zealand.

Additional online information about Hedychium gardnerianum is available from the Hawaiian Ecosystems at Risk project (HEAR).

Information about Hedychium gardnerianum as a weed (worldwide references) may be available from the Global Compendium of Weeds (GCW).

Taxonomic information about Hedychium gardnerianum may be available from the Germplasm Resources Information Network (GRIN).

References:

Baret, Stephane/Rouget, Mathieu/Richardson, David M./Lavergne, Christophe/Egoh, Benis/Dupont, Joel/Strasberg, Dominique. 2006. Current distribution and potential extent of the most invasive alien plant species on La Réunion (Indian Ocean, Mascarene islands). Austral Ecology (2006) 31, 747-758.

Bishop Museum (Honolulu). 1990. Voucher specimen #BISH 664890 (Sykes, W.R. 473845).

Comité français de l'Union Internationale pour la Conservation de la Nature en France. 2010. Les espéces envahissantes en outre-mer (online resource).

Florence, J./Chevillotte, H./Ollier, C./Meyer, J.-Y. 2011. Base de données botaniques Nadeaud de l'Herbier de la Polynésie Française (PAP). (online resource).

Fosberg, F. R. 1997. Preliminary checklist of the flowering plants and ferns of the Society Islands. Ed. by David R. Stoddart. U. Cal. Berkeley.

Fosberg, F. R./Sachet, Marie-Hélène/Oliver, Royce. 1987. A geographical checklist of the Micronesian monocotyledonae. Micronesica 20:1-126.

Healy, A. J./Edgar, E. 1980. Flora of New Zealand, Volume III: Adventive cyperaceous, petalous & spathaceous monocotyledons. Government Printer, Wellington, New Zealand. 220 pp.

Herrera, Katherine/Lorence, David H./Flynn, Timothy/Balick, Michael J. 2010. Checklist of the vascular plants of Pohnpei with local names and uses. Allertonia, in press. National Tropical Botanical Garden, Lawai, Hawai‘i. 146 pp.

Lavergne, Christophe. 2006. List des especes exotiques envahissantes a La Reunion. Unpublished manuscript (Excel file). .

MacDonald, I. A. W./Thebaud, C./Strahm, W. A./Strasberg, D. 1991. Effects of alien plant invasions on native vegetation remnants on La Reunion (Mascarenes Islands, Indian Ocean). Environmental Conservation 18 (1):51-61.

MacKee, H. S. 1994. Catalogue des plantes introduites et cultivées en Nouvelle-Calédonie. Muséum National d'Histoire Naturelle, Paris, 164 p.

McCormack, Gerald. 2011. Cook Islands Biodiversity Database, Version 2007.2. Cook Islands Natural Heritage Trust, Rarotonga.

Owen, S. J. 1997. Ecological weeds on conservation land in New Zealand: A database. Working draft. Wellington, New Zealand. Department of Conservation.

Queensland Herbarium. 2002. Invasive Naturalised Plants in Southeast Queensland, alphabetical by genus. Modified from: Batianoff, George N. and Butler, Don W. (2002). Assessment of Invasive naturalized plants in south-east Queensland. Appendix. Plant Protection Quarterly 17, 27-34. 11 pp.

Smith, Albert C. 1979. Flora Vitiensis nova: a new flora of Fiji. National Tropical Botanical Garden, Lawai, Kauai, Hawaii. Volume 1. 494 pp.

Smith, Clifford W. 1985. Impact of Alien Plants on Hawai‘i's Native Biota. In: Stone, Charles P. and Scott, J. Michael, eds. Hawai‘i's terrestrial ecosystems: preservation and Management. Cooperative National Park Resources Studies Unit, University of Hawaii, Manoa.

Smith, Clifford W./ Denslow, Julie/ Hight, Stephen. 2002. Proceedings of workshop on biological control of native ecosystems in Hawai‘i. Pacific Cooperative Studies Unit (University of Hawaii at Manoa, Department of Botany) Technical Report 129. 122 pages.

Space, James C./Flynn, Tim. 2002. Report to the Government of the Cook Islands on invasive plant species of environmental concern. USDA Forest Service, Honolulu. 146 pp.

Staples, George W./Herbst, Derral R./Imada, Clyde T. 2006. New Hawaiian plant records for 2004. In: Evenhuis, Neal L. and Eldredge, Lucias G., eds. Records of the Hawaii Biological Survey for 2004-2005. Part 2: Notes. Bishop Museum Occasional Papers 88:6-9.

Thaman, R. R./Tuiwawa, M. 1999. Invasive, potentially invasive and adventive alien plant species of Fiji: a preliminary analysis of their status and measures required for their control. Preliminary draft discussion paper prepared for the SPREP Regional Invasive Species Strategy for the South Pacific Islands Region: Regional Workshop, Nadi, Fiji, 26 September-1 October 1999.

Timmins, S. M./Mackenzie, I. W. 1995. Weeds in New Zealand protected natural areas database. Wellington, New Zealand. Department of Conservation, , Technical Series No. 8. 287 pp.

U.S. Dept. Agr., Agr. Res. Serv. 2011. National Genetic Resources Program. Germplasm Resources Information Network (GRIN). Online searchable database.

Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. 1999. Manual of the flowering plants of Hawaii. Revised edition. Bernice P. Bishop Museum special publication. University of Hawai‘i Press/Bishop Museum Press, Honolulu. 1919 pp. (two volumes).

Weber, Ewald. 2003. Invasive plants of the World. CABI Publishing, CAB International, Wallingford, UK. 548 pp.

Whistler, W. A. 2000. Tropical ornamentals: a guide. Timber Press, Portland, Oregon. 542 pp.

Wu, Te-lin. 2001. Check List of Hong Kong Plants. Hong Kong Herbarium and the South China Institute of Botany. Agriculture, Fisheries and Conservation Department Bulletin 1 (revised). 384 pp.