Mikania Vine (Mikania micrantha) is a branched, slender-stemmed perennial vine with ribbed stems to 6 m long. The heart-shaped or triangular leaves are borne in opposite pairs along the stems, have 2 to 8 cm long stalks, 3 prominent veins and vary from 4-13 cm long. Numerous 'fluffy' flower-heads (capitula) are borne in branched clusters originating in the forks (axils) of the leaves or forming at the tips of the branches. These flower-heads are small (3-6 mm long), greenish-white or white in colour, consist of four individual 'florets', and lack obvious petals (i.e. they have no ray florets). The black 'seeds' (achenes) are linear-oblong, 5-angled and 1.5 to 2 mm long. Each seed is surmounted by a tuft (a pappus) of 30 or more fine white bristles (Navie 2004; GISD 2005; NRW 2005).
For further information and assistance with identification of Mikania Vine contact the herbarium in your state or territory.
Mikania Vine is naturalized in coastal north-east Queensland and also on Christmas Island (NRW 2005).
|Key points:|| |
- Mikania Vine (Mikania micrantha) is a serious pest in the Pacific Islands, South-East. Asia, Indonesia and New Guinea.
- It has the potential to become a major pest of the Queensland Wet Tropics and other humid regions of northern Australia.
- It rapidly chokes and smothers areas it has recently colonized, including natural vegetation and agricultural crops, destroys the natural environment and drives out native animals.
- This species has been nominated as among 100 of the "World's Worst" invaders.
|How it spreads:|
Each Mikania Vine plant produces tens of thousands of fine, fluffy seeds which are wind-dispersed or moved on clothing or animal hair and by machinery or water. Plants can root from the nodes, and spread is aided by cultivation that breaks up the runners and moves viable pieces. A single plant may cover over 25 square metres within a few months, and release as many as 40 000 viable seeds every year (GISD 2005; NRW 2005).
|Where it grows:|
Mikania Vine invades agricultural areas, coastland, disturbed areas, natural forests, planted forests, riparian zones, scrub/shrublands, urban areas, wetlands and some crops. It flourishes where fertility, organic matter, soil moisture, and humidity are all high. It can tolerate some shade (Navie 2004; GISD 2005).
This species has been nominated as among 100 of the "World's Worst" invaders (GISD 2005).
Once established, Mikania Vine spreads at an alarming rate, climbing readily and twining on any vertical support, including crops, bushes, trees, walls and fences. Its shoots have been reported to grow up to 27 mm a day. Vegetative reproduction is also efficient and vigorous. Although intolerant of heavy shade it readily colonises gaps (GISD 2005).
Vigorous infestations damage or kill other plants by cutting out the light and smothering them. In this respect it is especially damaging in young plantations and nurseries. It also competes for water and nutrients, but perhaps even more importantly, it is believed that the plant releases substances that inhibit the growth of other plants (GISD 2005).
Mikania Vine is a major environmental weed, as well as a pest in plantation crops and commercial forests, from West Africa through India to south-east Asia and the Pacific Islands. Thriving in humid tropical areas, it has the potential to cause serious damage to agriculture (including sugar cane, tropical fruit and vegetable production) and native vegetation in northern Australia (NRW 2005).
Several of the known infestations abut the rainforests of the Wet Tropics World Heritage Area in north Queensland (Waterhouse 2003). These forests could be threatened if this weed was to spread (NRW 2005).
Mikania Vine is native to Central and South America, where it grows in and near forests, along rivers and streams and in disturbed areas such as roadsides (GISD 2005).
Mikania Vine was first recorded in mainland Australia in June 1998, with the discovery of three small infestations at Bingil Bay, Mission Beach and Forrest Beach in north Queensland. In 2001, several additional infestations were discovered at Speewah and Ingham, also in north Queensland, but the total (known) infested area remains at less than 30 hectares. Several of the infestations abut rainforests of the Wet Tropics World Heritage Area. Although their origin is unclear, the infestations at Bingil Bay, Mission Beach and Forrest Beach were related. At Mission Beach and Forrest Beach plants had been intentionally cultivated for use as an herbal remedy for skin infections. The origin of the Ingham infestation is unknown. Circumstantial evidence suggests a separate introduction to Speewah, possibly as a contaminant of imported palm seeds. All known infestations are now targets of an eradication campaign (Waterhouse 2003).