Taxonomic name: Miconia calvescens D.C.
Synonyms: Cyanophyllum magnificum Groenland 1859, Miconia magnifica Triana 1871
Common names: bush currant (English), cancer vert (French), miconia (English), purple plague (English), velvet tree (English)
Organism type: tree A highly ornamental tree from South America, Miconia calvescens was introduced to a botanical garden on the island of Tahiti in 1937. Its huge red and purple leaves made Miconia calvescens highly desirable for gardeners and was spread into the wild by fruit-eating birds. Today, more than half of Tahiti is heavily invaded by this plant. Miconia calvescens has a superficial and tentacular rooting system that contributes to landslides. It has also become the dominant canopy tree over large areas of Tahiti, shading out the entire forest understorey. Scientists estimate that several of the island’s endemic species are threatened with extinction as a result of habitat loss due to Miconia calvescens. It has been introduced to other Pacific islands, including Hawaii where it was introduced as an ornamental in the 1960s. The plant has since been found in many locations on the Hawaiian Islands. It is still sold as an ornamental plant in the tropics. Description
A medium-sized tree up to 15m in height with opposite large attractive leaves up to 80cm long, dark green above with three prominent pale green nerves, purple-blue beneath; with small white flowers, slightly fragrant, arranged in large panicles up to 30cm long; with fleshy berries ca. 7mm in diameter, purple-black when mature. Occurs in:
coastland, natural forests, planted forests, riparian zones, ruderal/disturbed, scrub/shrublands, urban areas, wetlands General impacts
Miconia forms dense monospecific stands shading out native vegetation with its large leaves, and suppressing the growth and regeneration of the native species in the understory. In Tahiti, it covers more than 70% of the island. Between 40 to 50 rare endemic plant species are directly threatened in Tahiti (Society Is.). The tentacular root system is also suspected to favour soil erosion and landslides. Geographical range
Native range: Native to tropical America. Introduction pathways to new locations
Other: Long distance dispersal by birds is suspected but unproven.
Road vehicles (long distance): Boat transportation of dirty machinery and vehicles to the remote island of Nuku Hiva and Fatu Hiva (Marquesas Is.).
Taken to botanical garden/zoo: Papeari botanical garden (Tahiti, 1937).
Local dispersal methods
Consumption/excretion: Fruits eaten and seed dispersed by frugivorous birds and rodents. Individual birds can carry thousands of seeds at least upto 2km.
Garden escape/garden waste: It has spread in the islands of Tahiti, Moorea, Raiatea (Society Is.) where it was cultivated as an ornamental.
Hikers' clothes/boots: Including botanists!
Other (local): In the hooves of feral goats and pigs.
Road vehicles: Sticks to dirt/soil on wheels.
Translocation of machinery/equipment (local): Machinery used for hydro-electrecity (Tahiti), road construction (Marquesas Is.) or small water-tank construction (Austral Is.). Management information
Preventative measures: A Risk Assessment of
Miconia calvescens 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 14 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."Physical: Hand-removal of seedlings and juvenile plants (< 3 m). Chemical:Cut-stump treatment of trees using herbicides (Garlon, Triclopyr+2,4-D). Nutrition
No information available, but Miconia plants can tolerate otherwise poor growing conditions if adequate moisture is available. Reproduction
Sexual reproduction, and vegetative propagation (by cuttings). Self-fertilisation occurs. Facultative xenogamy.
At least three major flowering peaks per year. A single tree can bear up to 220 inflorescences with an average of 1330 flowers/inflorescence, an average of 208 fruits/infrutescences, and 195 seeds/fruit. Its seeds can live for more than 10 years in soil. Lifecycle stages
Photo-sensitive seeds, but can germinate even in dense shade (0.02% of full sun). Germination rate up to 90% in 15-20 days. Soil seed bank > 50,000 seeds/m². Longevity of the soils seed bank > 6-8 years. First year of flowering after 4 to 5 years of vegetative growth . Growth rate ca. 1 m/yr for seedling and juvenile plants. This species has been nominated as among 100 of the "World's Worst" invaders Reviewed by: Major update under progress
Dr. Jean-Yves Meyer, Directeur scientifique, Conservatoire Botanique National de Mascarin (CBNM), Domaine des Colimaçons, ILE DE LA REUNION (FRANCE).
Compiled by: Dr. Jean-Yves Meyer, Directeur scientifique, Conservatoire Botanique National de Mascarin (CBNM), Domaine des Colimaçons, ILE DE LA REUNION (FRANCE) & IUCN/SSC Invasive Species Specialist Group (ISSG)
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Last Modified: Thursday, 21 September 2006
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