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Hedychium gardnerianum

Perennial herb up to 1,5-3 m, rhizomatous, with yellow fragrant flowers and arranged in upright inflorescences.

Scientific name: Hedychium gardnerianum Sheppard ex Ker Gawl.

Common names: kahili ginger, kahila garland-lily, wild ginger

Family: Zingiberaceae

Status in Portugal: invasive species (listed in the Plano regional de erradicação e controlo de espécies de flora invasora em áreas sensíveis and Decreto-Lei nº 92/2019, 10 july)

Risk Assessment score: 18 | Value obtained according to a protocol adapted from the Australian Weed Risk Assessment (Pheloung et al. 1999), by Morais et al. (2017), according to which values above 13 mean that the species has risk of having invasive behavior in the Portuguese territory | Updated on 30/09/2017.

Synonymy: Gamochilus speciosus T. Lestib., Hedychium pallidium Regel, Hedychium gardnerianum var. pallidium Regel

Last update: 11/07/2021

Family: 
Zingiberaceae
Appearence: 
Grasses and herbs

How to recognise it

Perennial herb up to 1,5-2 m, with rhizomes of large dimensions, with leafy stems and aromatic flowers arranged in large erect inflorescences.

Leaves: alternate, oblong to lanceolate, sessile, acuminate, entire, with 20-60 x 5-12,5 cm, dark-green and glabrous on the upper surface and sparsely pubescent and whitish on the lower surface.

Flowers: yellow with only one red stamen, tubular, arranged in erect inflorescences (spikes), ovoid, with 15-20 x 8 cm.

Fruits: capsules up to 1,5 cm long, orange-red within, containing numerous small seeds (5-6 mm), reddish and wrapped by an aril.

Flowering: July to October.

 

Similar species

There are other species of Hedychium with which Hedychium gardnerianum may be mistaken with. Meanwhile, the colour of the flowers is a distinctive characteristic. In the Azores archipelago Hedychium coronarium J.Koenig is also invasive and is distinguished from Hedychium gardnerianum because it has white flowers.

 

Characteristics that aid invasion

It propagates by seed, producing a high number of seeds (each spike has, in mean, between 300 to 500 seeds) that are easily dispersed by wind, water and birds.

It also propagates vegetatively, by rhizomes.

Native distribution area

Asia (India, east from the Himalayas and Nepal).

 

Distribution in Portugal

Azores archipelago (all islands), Madeira archipelago (Madeira island).

 

Geographic areas where there are records of Hedychium gardneranium

Other places where the species is invasive

Europe (Spain, France), Pacific island (Micronesia, Cook, French Polynesia), North America (USA – Hawaii), Australia, New Zealand, South America (Caribbean), South Africa.

 

Introduction reasons

Ornamental purposes.

 

Preferential invasion environments

Along watercourses, roadsides, disturbed areas, forests and crop areas.

It also invades natural and semi-natural areas.

Impacts on ecossystems

The rapid growth leads to the formation of dense and impenetrable areas that inhibit the development of native vegetation.

 

Economic impacts

High costs in the application of control methodologies.

On the banks of streams, when in large amounts, it may obstruct the drainage channels, consequently enhancing flood risk.

 

Other impacts

Very aromatic plant, being able to cause allergic reactions.

Controlling an invasive species demands a well-planned management, which includes the determination of the invaded area, identifying the causes of invasion, assessing the impacts, defining the intervention priorities, selecting the adequate control methodologies and their application. Afterwards it is fundamental to monitor the efficiency of the methodologies and recuperation of the intervened area as to perform, whenever necessary, the follow-up control.

The control methodologies used for Hedychium gardnerianum include:

 

Physical control

Hand pulling: preferential methodology for small invaded areas. In more compacted substrates, hand pulling must be made during the rainy as to facilitate the removal of the root system. As much as possible, it should be guaranteed that there are no rhizomes and/or large rhizome fragments left in the ground because they regenerate very vigorously, diminishing the efficacy of this methodology.

 

Physical + chemical control

Cut stump method: methodology applicable to large invaded areas. The stems should be cut as close to the ground as possible and applied herbicide (active substance: metsulfuron-methyl) to the cut surface. Some authors refer that the sprouts are more sensitive to herbicide so, alternatively, the application of herbicide may be done when the sprouts achieve 50 to 60 cm high.

 

Chemical control

Foliar application of herbicide:methodology applicable to seedlings and young plants, up to 50 cm high. Spray with herbicide (active principle: metsulfuron-methyl) limiting the exposure to the target species. It should be made on the time of the plants’ greater growth.

 

Biological control

The bacteria Ralstonia solanacearum (E. F. Smith) was tested in Hawaii, as a biological control agent of Hedychium gardnerianumbut, its use is not yet authorized.

This agent has not yet been tested in Portugal as to verify its safety relatively to  native species,  so its use has not yet constituted an alternative in our country.

 

Visit the webpage How to Control for additional and more detailed information about the correct application of these methodologies.

Anderson RC, Gardner DE (1999) An evaluation of the wilt-causing bacterium Ralstonia solanacearum as a potential biological control agent for the alien kahili ginger (Hedychium gardnerianum) in Hawaiian forests. Biological Control 15(2): 89-96.

 

 

CABI (2013) Hedychium gardnerianum. In: invasive">Invasive species">Species Compendium. CAB International, Wallingford, UK. Available: http://www.cabi.org/isc/ [Retrieved 06/01/2013].

 

 

 

 

Cordeiro N, L Silva (2003) Seed production and vegetative growth of Hedychium gardnerianum Ker-Gawler (Zingiberaceae) in São Miguel Island (Azores). Arquipélago, Life and Marine Sciences 20A: 31-36.

 

 

 

 

Csurhes S, Hannan-Jones M (2008) Pest plant risk assessment: Kahili ginger (Hedychium gardnerianum), White ginger (Hedychium coronarium), Yellow ginger (Hedychium flavescens). Biosecurity Queensland, Department of Primary Industries and Fisheries, Brisbane,  22pp.

 

 

 

 

DAISIE European invasive">Invasive Alien species">Species Gateway (2013) Hedychium gardnerianum. Available: http://www.europe-aliens.org/speciesFactsheet.do?speciesId=5464# [Retrieved 06/01/2013].

 

 

 

 

Global invasive">Invasive species">Species Database (2005) Hedychium gardnerianum. Available: http://www.issg.org/database/species/ecology.asp?si=57&fr=1&sts=sss&lang=EN [Retrieved 06/01/2013].

 

 

 

 

Govaerts R (2013) Hedychium gardnerianum Sheppard ex Ker Gawl. Facilitated by the Royal Botanic Gardens, Kew. Available: http://apps.kew.org/wcsp/ [Retrieved 06/01/2013].

 

 

 

 

Penacho ML, Amaral RS, Malveiro A, Machado CAS, Aranha JTM (2009) Controlo de invasoras Hedychium gardnerianum e Gunnera tinctoria em áreas florestais na ilha de S. Miguel – Açores. In: SPCF (ed) 6º Congresso Florestal Nacional: A floresta num mundo globalizado, Ponta Delgada, Açores, pp. 802-806.

 

 

 

 

PIER (Pacific Island Ecosystems at Risk) (2003) Hedychium gardnerianum. Available: http://www.hear.org/pier/species/hedychium_gardnerianum.htm [Retrieved 06/01/2013].

 

 

 

 

Silva L, Corvelo R, Moura M, Fernandes FM (2008) Hedychium gardnerianum Sheppard ex Ker Gawl. In: Silva L, Land EO, Luengo JLR (eds) Flora e fauna terrestre invasora na Macaronésia. Top 100 nos Açores, Madeira e Canárias. Arena, Ponta Delgada, pp. 217-220.