Hedychium gardnerianum in the EPPO region: addition to the EPPO Alert List
Why
Hedychium gardnerianum (Zingiberaceae) is recorded as established in the EPPO region where it forms dense stands which have impacts on biodiversity and ecosystem services. The EPPO Panel on Invasive Alien Plants are seeking further information on any additional occurrences of H. gardnerianum the EPPO region.
Geographical distribution
EPPO region: Portugal, Spain, United Kingdom
Africa: Kenya, Mauritius, Reunion, South Africa, Zimbabwe
Asia: Bhutan*, China (Yunnan*), India* (Arunachal Pradesh, Assam, Manipur, Meghalaya, Nagaland, Sikkim), Japan, Myanmar*, Nepal*, Thailand, Vietnam
North America and the Caribbean: Mexico, USA (Hawaii)
Central America and Caribbean: Cuba, Dominican Republic, Guadeloupe, Haiti, Honduras, Martinique, Trinidad and Tobago
South America: Brazil, Ecuador (Galapagos)
Oceania: Australia (New South Wales, Queensland, South Australia, Tasmania, Victoria), Cook Islands, Fiji, French Polynesia, Federated States of Micronesia, New Caledonia, New Zealand
* = Native distribution
Morphology
Hedychium gardnerianum is a perennial, clump forming herb with leafy shoots growing up to 2 m high. It has thick rhizomes which grow close to the ground surface. Flowers are yellow and grow in an inflorescence which is 25-40 cm long.
Biology and Ecology
Hedychium gardnerianum is a vigorous growing species with high seed production and a dense rhizome system.
Small pieces of rhizomes can be regenerate into viable plants.
Habitats
In its native range, H. gardnerianum grows in mountainous areas up to an altitude of 2500 m. In its native range it is an understory species in forests and woodlands. In its invasive range, H. gardnerianum can grow in a number of different habitats including watercourses, roadsides, disturbed areas, forests and crop areas. It grows in a number of different soil types but prefers moist, wet, and well-drained soils.
Pathways for movement
International pathways include plants for planting and cut flower trade. Reproductive plant material (seed and rhizomes) can be a contaminant of garden waste or soil or other growing media, which can aid local movement. Natural spread is by seed. H. gardnerianum produces a large quantity of seed which is dispersed by birds over short distances and by human assisted means over long distances (via the horticultural industry or in garden waste).
Impacts
Hedychium gardnerianum can act as a habitat transformer. It can prevent forest regeneration. It displaces native plants, forms vast, dense colonies and suppresses understorey vegetation. It can block stream edges, altering water flow and access to the water. It can increase erosion from riverbanks.
Control
Management measures include physical and mechanical control measures. Control using herbicides is possible, however, their use in certain habitats is restricted. Biological control, using natural enemies from the plants’ native range shows promise.
Sources
Hu X, Mou FJ, Meng TY, Li YG (2023) A new record of Hedychium gardnerianum (Zingiberaceae) from southwest China reveals an update to its distribution range. Israel Journal of Ecology and Evolution, 2224-4662
Pereira MJ, Eleutério T, Meirelles MG, Vasconcelos HC (2021) Hedychium gardnerianum Sheph. ex Ker Gawl. from its discovery to its invasive status: a review. Botanical Studies62, 11. https://doi.org/10.1186/s40529-021-00318-5
Rojas-Sandoval J (2023) Hedychium gardnerianum (kahili ginger). CABI Compendium, 26679. https://doi.org/10.1079/cabicompendium.26679