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Description: The genus Hedychium includes about 40-50 “robust rhizomatous herb species native from Malaysia to India and possibly Madagascar;” and numerous Hedychium species planted by people because of the “conspicuous, often aromatic flowers, and some for their rhizomes, which are used to make perfume” (Whistler 2000:236). Here we focus on Hedychium coronarium, known in English as “White Ginger,” which an erect, perennial, unbranched, rhizotamous herb that produces leafy shoots 1-2 m (3-6 ft) tall. Its leaves are simple, alternate, and two-ranked with elliptic to lanceolate blades 20-30 cm (8-12 in) long and 3-10 cm (1-4 in) wide; the lower surfaces have hairs. White Ginger produces many fragrant flowers throughout the year that are white and butterfly-shaped. The fruits capsules are oblong and many-seeded, but only formed infrequently under cultivation (e.g., see Whistler 2000:237).
Distribution: Hedychium coronarium is probably native to the Himalayas and southwestern China. It is widely cultivated in the tropics and frequently escapes cultivation to become naturalized (growing wild) in various places, including in some Micronesian Islands where it was only introduced in recent times. It is well-adapted to wet habitats, and can be found in moist forests, roadsides, open areas, and along streams. Unfortunately, the creeping growth of this aromatic herb “overwhelms low-growing plants in pastures and forests” and therefore is capable of forming dense, single species stands by vegetative spread through the expansion of a dense rhizome (Motooka et al., 2002).
Uses by Island or Island Group: The flowers of Hedychium coronarium are used for garlands and other decorations throughout the region where this species is found as a native, and more so as an introduced species. The white ginber, H. coronarium has also been used for medicinal purposes; for example, as a remedy for tonsillitis, swellings and as an anti-rheumatic. For this therapeutic use and others, White Ginger appears to have been traded worldwide for hundreds of years. Overharvesting for medicinal and other uses may explain why H. coronarium became an “endangered medicinal and aromatic plant in Madhya Pradesh and Chotanagpur, Bihar, India” (Chadha 2005). On the other hand, this widely cultivated, garden ornamental plant is also regarded as a potentially invasive weedy species in many tropical areas. Its likelihood of becoming a problematic weed in humid island environments may be similar to “Kahili Ginger” (Hedychium gardnerianum) and “Yellow Ginger” (Hedychium flavescens), which are both aggressive invaders of those native forests into which they have been introduced (e.g., see Csurhes and Hannan-Jones 2008). Meyer (2000) reviewed the weed status of the Hedychium spp., including H. coronarium, in the Pacific Island nations and listed their status as potential problem weeds in Palau while they were already considered to be a moderate pest in the Federated States of Micronesia. More recently, Chiba de Castor et al. (2016:55) claimed to have demonstrated experimentally that the success of an invasive plant species, such as the white ginger, depends upon its competitive advantage in the new community into which it has invaded, and in the case of white ginger, H. coronarium the significance of different possible growth patterns:
“This advantage can be attributed to high phenotypic plasticity, which either allows the plant to develop under a broad variety of environmental conditions, or grants it with a higher fitness compared to native species. In the present study, we assessed the development of the invasive white ginger lily, Hedychium coronarium, and plant community through removal experiments, under different conditions of soil moisture in riparian areas. We observed that H. coronarium exhibited different invasion strategies according to soil moisture, plant community species life form, and intensity of intra- and interspecific competition. In areas with high soil moisture and high competitive pressure, H. coronarium invests in height growth rather than new ramets. In areas with drier soils and lower competitive pressure, H. coronarium expands its population through new ramets. Our results suggest H. coronarium has a negative influence on the recruitment of plants from the plant community, with consequences to the biodiversity of invaded areas.”
Uses in Palau: Hedychium coronarium (white ginger) was probably introduced to Palau by the Japanese during the 20th century. This ginger has been used in Palau as a floral ornament for more than a half century, as noted on voucher specimen collected by Fosberg on Koror Island in 1950 and deposited Smithsonian Museum, National Museum of Natural History. However, more recently H. coronarium has been observed not only in cultivation in some areas of Palau (Space et al. 2003), but more recently has been referred to as a planted herb with potential invasive species capabilities in this and other island nations.
“[H. coronarium] (white ginger) was seen in cultivation on Koror, on Ngerkebesang and in Airai just beyond the Koror-Babeldaob Bridge. This and other Hedychium species can be quite invasive in wetlands and in moist areas under the forest understory and are difficult to control. Hedychium species have become extensively established in Hawai‘i, where they are a major problem. [H. coronarium (white ginger)] is a ‘high risk’ species, with a weed risk assessment score of 10” (Space et al. 2009).
Uses in Yap and its outer islands: Introduced into Yap State in recent times, Hedychium coronarium,known locally as Chawiwi, Chabubu, Sifif nisepan or Trewiwi, on Yap proper. This alien ginger is planted, probably as an ornamental and for its fragrant flowers, in some areas of Yap and on some of the outer islands and atolls. Reportedly it has become invasive in some these and other tropical islands in the Pacific region (Meyer 2000:90).
Uses in the Mariana Islands: Stone (1964:133, 1970:111) reported white ginger, Hedychium coronarium, as a recently introduced plant on Guam where it is planted principally as an ornamental. Falanruw et al. (1989:10) described the agroforest areas on Rota, Tinian and Saipan in the Commonwealth of the Northern Mariana Islands that were still present at the time of their survey of the vegetation on these islands; and within these agroforest areas, these researchers noted the occurrence of “white ginger (Hedychium coronarium) growing as one of the “common ornamentals” in the “understory” of this cultivated vegetation type.
Uses in Chuuk and outer islands: On Chuuk the leaves of this introduced and cultivated ginger plant are often used as a covering for earth ovens (Merlin and Juvik 1996). On both Namulok (Nómwunuuk) and Puluwat (Pwonowót) Atolls the flowers of Hedychium coronarium are woven into garlands, and on Satawal (an outer atoll of Yap State) they are used in marumar garlands and grown near villages as an ornamental (Fosberg 1969).
Uses in Pohnpei: Hedychium coronarium was introduced into Pohnpei in relatively recent times and planted as an ornamental; however, white ginger has escaped cultivation and become an invasive species in some areas of this island (Meyer 2000:90). Balick and his colleagues (2009:314) referred to the use of the attractive budding flowers of the white ginger (H. coronarium) in head garlands or lei on Pohnpei; furthermore, they reported that these same flowers are used to condition human hair, making it sweet-smelling and gleaming: for example, unopened flower buds of this ginger plant on Pohnpei are “collected before the sunrise, pounded with grated conconut (Copra, Cocos nucifer), and massaged into the hair in the morning and washed out in the evening.” Balick and his colleagues (2009:315) also described therapeutic use of the cleaned rhizome of this ginger which is scraped into a piece of cloth from which drops are squeezed into the eyes of people suffering from irritations such as “conjunctivitis (red eye or pinkeye).”
Uses in Kosrae: Introduced in recent times and planted as an ornamental, Hedychium coronarium has escaped cultivation and become an invasive ginger species in some areas of the island (Meyer 2000:90). As a Popular scented garden plant, white ginger, H. coronarium, was apparently first collected in Kosrae as an herbarium specimen in 1958. Now this alien ginger is reportedly seen in many Kosraean gardens, and “is quite possible that it will spread further” on this Micronesian Island with potential to be “a significant weed of forests and stream bank areas, preventing the regeneration of native species in these habitats,” and thus the invasive potential of this white ginger requires “further investigation as to taxonomy, confirming native range and/or invasiveness, and dependent on these results, their suitability for control or possible future biocontrol programmes should be further investigated” (see Sanney and Mather 2013).
Uses in Nauru: Introduced in recent times and planted as an ornamental (Fosberg et al. 1987:113; Thaman et al. 1994:76).