The velvet tree, miconia, or bush currant (Miconia calvescens) is a species of flowering plant in the family Melastomataceae. It is native to Mexico and Central and South America and it has become one of the worlds most invasive species.
Miconia trees can flower several times a year and bear fruit simultaneously. The flowers are large inflorescences of light pink blossoms and the tiny purple fruits are half a centimeter in diameter and packed with minuscule seeds. The sweet fruits are attractive to birds and other animals which disperse the seeds. This heavy seed production and potential for long-distance dispersal help make miconia a threat. The seeds lie dormant in the soil of the forest, and whenever a break in the canopy allows sun to shine through to a patch of soil the seeds there undergo germination. Once the plants grow to full height, their enormous leaves shade out all the space below them, preventing any other plant from growing nearby. It also has a shallow root system that facilitates soil erosion.
The tree can grow to a height of 15 metres (49 ft) and has very large leaves, each up to 1 metre (3.3 ft) in length. Its purple and green leaves with flashy white veining made it attractive as an ornamental, and it was imported to Hawaii and other new areas in the mid-twentieth century.
Once it dispersed into the tropical moist forests it took hold vigorously, invaded any spot in the understory that received patches of sunlight, and became a noxious weed. It is known for being the worst invasive plant in Hawaii, where it is commonly referred to as the "purple plague", and threatens to destroy entire ecosystems. Hawaiian populations of miconia were first discovered in the 1990s, and since the plant's invasive potential was already well-known, control and eradication efforts began immediately. Uprooting and herbicides are used to remove plants, but biological control has not yet met with great success. Teams of volunteers often lead expeditions into the forest to remove miconia plants by hand.
The tree has become an invasive species in Tahiti and a quarter of the rainforest on the island is now made up of miconia stands. For this reason, it is frequently called the "green cancer" on the island.
- "Miconia calvescens". Germplasm Resources Information Network. United States Department of Agriculture. 1997-12-10. http://www.ars-grin.gov/cgi-bin/npgs/html/taxon.pl?409651. Retrieved 2009-02-07.
- "100 of the World's Worst Invasive Alien Species". Global Invasive Species Database. http://www.issg.org/database/species/search.asp?st=100ss. Retrieved 3 August 2012.