Invasive Species: Twin Mile-a-Minute - Twice the Fun

At America’s borders Homeland security is a big focus. Invasive species interdiction and control is efficiently carried on by the professional employees of the U.S. Customs and Border Protection given financial constraints under which they operate. Early Detection and Rapid Response (EDRR) should be their motto, as they tirelessly work to detect small isuues and cost effectively deal with them before they become uncontrolled and expensive problems without resolution.

On Thursday, February 12, 2009 I wrote about a success, Invasive Species Intercepted By Customs and Border Protection and this month another early detection and rapid response as U.S. Department of Agriculture (USDA) botanist identified a weed seed, discovered during a CBP inspection of pineapples that arrived aboard the M/V Eurus Lima from Costa Rica, as Mikania micrantha, also know as the invasive mile-a-minute weed.

Now to make things a little confusing as it seems it must be in invasive species this weed is called mile-a-minute just as the thorny vine growing in my lower field also called mile-a-minute. How can this be? It can be because using common names while seemingly simplifying things in the garden and landscape actually confuses the daylights out of most sane conversations, and is the reason scientific names (Latin sounding binomials) are preferred.

So mile-a-minute, Persicaria perfoliata, previously Polygonum perfoliatum, a.k.a. Asiatic tearthumb, (an apt name which, if you have not met this plant, when you do, you shall find yourself agreeing with me) in my garden is from India to Eastern Asia, China and the Islands from Japan to the Philippines, including Nepal, Burma, Manchuria, China, Korea, Taiwan and the Malay Peninsula.[1] This mile-a-minute already got past early detection and is way past rapid response in many gardens.

The newly apprehended and hopefully soon to be deported or otherwise summarily disposed of mile-a-minute is Mikania micrantha, a perennial creeping climber known for its vigorous and rampant growth. It grows best where fertility, organic matter, soil moisture and humidity are all high (such as agricultural fields and gardens). It damages or kills other plants by cutting out the light and smothering them. A native of Central and South America, Mikania micrantha was introduced into India after the Second World War to camouflage airfields and is one of the most widespread and problematic weeds in the Pacific region. Its seeds are dispersed by wind and also on clothing or hair. Once established, Mikania micrantha spreads at an alarming rate, readily climbing and twining on any vertical support, including crops, bushes, trees, walls and fences. Its shoots have been reported to grow up to 27mm a day. Vegetative reproduction is also efficient and vigorous. Although intolerant of heavy shade it readily colonizes gaps. [2] I note that one of the many additional common names for this species is bitter vine; I hope that we can adopt this as a differentiating name from the mile-a-minute in my garden, and from my invasive conversations.

picture on right: www.invasive.org/images/768x512/0002109.jpg
Image may be subject to copyright
Photographer: Yun Wu, USDA Forest Service, United States

picture on left: www.columbia.edu/.../image002.jpg
Image may be subject to copyright.

[1] Plant Conservation Alliance, Alien Plant Working Group: http://www.nps.gov/plants/ALIEN/fact/pepe1.htm
[2] IUCN/SSC Invasive Species Specialist Group (ISSG); http://www.issg.org/database/species/ecology.asp?si=42