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, ginger-lily, kāhili ginger, kahili ginger-lily, 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:  Bhutan, India (Assam, Sikkim), Nepal; naturalized elsewhere; widely cultivated in tropics (GRIN).

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 (2013)
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 (2013)
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. (2013) 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)	New South Wales	introduced invasive	National Herbarium of New South Wales (2013) Naturalised
Australia Australia (continental)	Australia (continental)	introduced invasive	National Herbarium of New South Wales (2013) Naturalised
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. (2013)

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).