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   Rhodomyrtus tomentosa (tree, shrub)  français     
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      Infestation in understory of pine flatwoods, Jonathan Dickinson State Park, Florida (Photo: Jennifer Possley, University of Florida, Center for Aquatic and Invasive Plants) - Click for full size   Post-cut resprouts. Jonathan Dickinson State Park, Florida (Photo: Jennifer Possley, University of Florida, Center for Aquatic and Invasive Plants) - Click for full size   Infestation in understory of pine flatwoods, Jonathan Dickinson State Park, Florida (Photo: Jennifer Possley, University of Florida, Center for Aquatic and Invasive Plants) - Click for full size
    Taxonomic name: Rhodomyrtus tomentosa (Aiton) Hasskarl 1842
    Synonyms: Myrtus canescens Lour., Myrtus tomentosa Aiton 1789, Rhodomyrtus parviflora Alston 1931 , Rhodomyrtus tomentosa Ait. Wight
    Common names: Ceylon hill gooseberry (English), downy myrtle (English-Florida), downy rose myrtle (English-Florida), feijoa (French), hill gooseberry (English), hill guava (English), Isenberg bush (English-Hawaii), myrte-groseille (French), rose myrtle (English-Florida)
    Organism type: tree, shrub
    Rhodomyrtus tomentosa is a large evergreen shrub native to Southeast Asia that has become an invasive species in other tropical and subtropical countries. Introduced to many areas as an ornamental plant, it has spread, forming large, monospecific thickets that displace native flora and fauna. Areas especially affected include Florida, Hawai‘i and French Polynesia.
    Description
    A large shrub to small tree, up to 12 feet tall. Leaves 2 to 3 inches long, 3-veined from the base, oval, obtuse to sharp pointed at the tip, glossy green above, densely grey or rarely yellowish-hairy beneath, entire, with wide leafstalk. Flowers 3/4 to 1 inch wide, solitary or two to three; petals tinged white outside with purplish-pink or all pink. Fruit purple, round, 3- or 4-celled, capped with persistent calyx lobes, about 1/2 inch wide, soft with double row of seeds in each cell, edible (Haselwood, 1966 in PIER, 2003). Seeds disc-shaped. Forms dense, monospecific thickets.
    Occurs in:
    coastland, estuarine habitats, natural forests, riparian zones, wetlands
    Habitat description
    Moist and wet forests, bog margins, up to 2400m elevation (Hosaka and Thistle, 1954 in Langeland and Burks, 1999). Able to invade a range of habitats, from pine flatwoods to mangrove marshes (Center for Natural Resources, 2003). Grows in a wide range of soil types, including salty coastal soil, but is sensitive to heavy salt spray (Menninger, 1964 in Langeland and Burks, 1999). Frost-tolerant (Bailey and Bailey, 1976 in Langeland and Burks, 1999). 'Fire-adapted,' is able to resprout prolifically after fire (Center for Aquatic and Invasive Plants, 2001).
    General impacts
    Invades the understory of native pinelands in Florida, forming dense monoculture thickets that displace native flora and fauna through overcrowding and competition. Has the potential to alter the natural fire regimes of invaded areas (Center for Aquatic and Invasive Plants, 2001).
    Uses
    Has shown promise as a fire retardant species for use in fire breaks in the Himalayas (Ministry of Environment & Forests, 2003). Is aesthetically pleasing, hence its use as an ornamental and landscaping plant (Center for Natural Resources, 2003). Has sweet edible fruit, which can be made into pies and jams, or used in salads. The fruit is also a food source for birds and mammals (Center for Aquatic and Invasive Plants, 2001).
    Notes
    Introduced to Hawai‘i c.1920 (Degener, 1963 in Langeland and Burks, 1999). By the 1950s was forming impenetrable thickets on Kauai and Hilo (Hosaka and Thistle, 1954 in Langeland and Burks, 1999). Currently on the State of Hawai‘i noxious weed list (Meyer, 1998 in PIER, 2003).

    A serious problem on Raiatea, French Polynesia (Meyer, 1998 in PIER, 2003).

    Introduced to Florida in the 1920s by the US Department of Agriculture as an ornamental and landscape plant, as well as for its fruit (Gordon and Thomas, 1997 in PIER, 2003). It escaped cultivation soon after and has now spread to 17 counties (Center for Natural Resources, 2003).

    Research was conducted at the University of Florida 1998-2000 to describe the ecology and determine effective control methods for this species.
    Geographical range
    Native range: Southeast Asia, India, China, Malaysia, the Philippines.

    Known introduced range: China (Guangxi,Guizhou,Hunan,Yunnan, Hong Kong), Indonesia, Laos, Macao, Thailand, Vietnam, Australia, French Polynesia, Hawai‘i, and United States (PIER, 2003).
    Introduction pathways to new locations
    For ornamental purposes: Introduced to Florida by US Dept. of Agriculture in 1920s as a landscaping plant, for ornamentation, and for its edible fruit (Center for Natural Resources, 2003).
    Landscape/fauna "improvement": Introduced to Florida by US Dept. of Agriculture in 1920s as a landscaping plant, for ornamentation, and for its edible fruit (Center for Natural Resources, 2003).
    Nursery trade: No longer sold for ornamental use in Florida (Possley, pers. comm.).


    Local dispersal methods
    Consumption/excretion: Seed is spread by frugivorous birds and possibly mammals (Center for Aquatic and Invasive Plants, 2001).
    Escape from confinement: Escaped from cultivation in Florida. Now found in natural areas (Langeland and Burks, 1999).
    For ornamental purposes (local): No longer sold for ornamental use in Florida (Possley, pers. comm.).
    Other (local): A small number of people have grown this species for its fruit to be used in the food industry. Residents in and around the City of Estero in Lee County, Florida were known to make jam from this species. It could be bought in the 1990s but is no longer for sale (Possley, pers. comm.).
    Management information
    Preventative measures: A Risk Assessment of Rhodomyrtus tomentosa for Hawai‘i and other Pacific islands was prepared by Dr. Curtis Daehler (UH Botany) with funding from the Kaulunani Urban Forestry Program and US Forest Service. The alien plant screening system is derived from Pheloung et al. (1999) with minor modifications for use in Pacific islands (Daehler et al. 2004). The result is a score of 8 and a recommendation of: "Likely to cause significant ecological or economic harm in Hawai‘i and on other Pacific Islands as determined by a high WRA score, which is based on published sources describing species biology and behaviour in Hawai‘i and/or other parts of the world."

    Integrated management: Seedlings can be manually removed. Mature shrubs may be felled using a chainsaw or brush cutter and treating the stumps with a commercial herbicide (Stocker and Possley 2001).

    Reproduction
    Seeds are dispersed by frugivorous birds. Can only spread by seed drop, as it does not spread vegetatively (Center for Aquatic and Invasive Plants, 2001). Has a large amount of seed production and high germination rate (Center for Natural Resources, 2003). Berries usually contain 40-45 seeds (Possley, pers. comm.).
    Lifecycle stages
    Flowers abundantly in spring (Langeland and Burks, 1999). In Florida, fruits are ripe in August and September (Possley, pers. comm.).
    Reviewed by: Jennifer Possley, Fairchild Tropical Garden, Miami, Florida, USA.
    Compiled by: IUCN/SSC Invasive Species Specialist Group (ISSG)
    Last Modified: Friday, 30 December 2005


ISSG Landcare Research NBII IUCN University of Auckland