Welcome to the wonderful world of weedy plants!
Weeds are superevolutionary products of human civilizations and activities - without humans there would be no weeds, just wild plants.

Monday, October 21, 2013

The good side of an invasive

クズ (Kudzu) 

The non-native species Pueraria lobata, commonly known as kudzu (or sometimes mile-a-minute weed, but it is not the same plant as in this blogpost), is a creeping, climbing legume vine from japan and china. “Kudzu” literally means ‘plant’ in Japanese. Like most invasive species, kudzu is considered a noxious weed in our part of the world. The ecological damage caused by this plant is solely due to its ability to out-compete neighboring species for resources such as light. As it grows over other plants, its large leaves blocks sunlight and often plants beneath the kudzu are suffocated. 
Kudzu, The Vine That Ate the South
"The Vine that ate the south." Kudzu invasion in forest.
Creative Commons image by
Frank DiBona on Flickr.

In its home countries, however, it has proven to be a herbal remedy for a variety of troubles such as hair loss and alcoholism. Such two-sided traits beautifully sum up the contradiction of invasive species. Though malicious in some environments, invasive species can be used to our benefit in other area. As seen in our last post about invasives, significant efforts have been put in to mitigate these weeds. However, recent research has shown that some of their characteristics could be beneficial to society.

How did kudzu get here? In 1876, during the US’ 100th birthday exposition in Philadelphia, the Japanese government constructed a native Japanese garden for the exhibit. The imagery of the leaves appealed to many American gardeners leading to the vast spread of kudzu in local gardens as ornamental plants from a Florida nursery that propagated and sold the plant. Kudzu was also actively promoted as a forage plant and soil conservation plant in the US during 1930s and 1940s. But it didn’t stay in gardens and on roadsides, it quickly escaped and took over the native forest. 

In addition to this, the US Armed Forces used kudzu as camouflage for equipment in Vanuatu and Fiji in the Pacific. Needless to say, the plant has become classified as an “unwanted organism” in these countries too.
The root, flower and leaf from kudzu are used to make herbal medicines. In Traditional Chinese medicine, the use of natural resources is the norm. In fact, the use of herbal-based medication is still a leading treatment for disease in many areas of the world. Kudzu is noted to have been used in Chinese medicine before 600 AD. Its uses range from treatments of menopause symptoms, muscle pain, stomach pain, fever, diarrhea, sinus infections, high blood pressure, to irregular heartbeat, chest pain and various other illnesses.
This medicine features the roots and flowers of the Kudzu plant,
which aims to lessen the desire and craving for alcohol. In addition
it aids the body's natural detoxification processes.
Source: vitaminshoppe.com

Despite its popularity on the Asian continent, the herbal remedy from kudzu has so far lacked sufficient scientific evidence to prove any effects. So can this weed actually help the medical world?

Kudzu promises a remedy for an illness of much importance to society. It has been used to “cure” alcoholism, or more accurately, decrease the symptoms of drinking and the urge to do so. In 2012 Penetar et al published a study conducted at McLean (a hospital affiliated with Harvard University) on kudzu’s effects on alcohol consumption. It was found that physiologically, kudzu can increase the blood flow to the brain and heart. “Wherever blood goes, alcohol goes”, states professor Scott Lukas on the research team. The theory is that this allows for a quicker response time, and the ability for the body to have enough alcohol in less time. Simply put, you get drunk faster on less alcohol. 

First tested on rodents, the intake of alcohol decreased significantly in the lab results when they were given kudzu. When tested on humans, the group treated with kudzu drank significantly less than the placebo group. The research states that alcohol consumption was almost cut in half!  

More research into the how’s and why’s of such effects could lead to very improtant discoveries regarding potential contributions of this invasive species to medicine. 

Check out an old poem written on this historic weed!

Wednesday, October 2, 2013

The minute mile-a-minute mitigator

A minute of natural history

Mile-a-minute overtaking trees.
by Furryscaly via Flickr CC
Mile-a-minute (Persicaria perfoliata) is one of the most pervasive and damaging nonnative invasive plant species in the United States.  Mile-a-minute, a member of the Buckwheat family (Polygonaceae), was first introduced to the U.S. in 1890 from its indigenous range of Asian and Southeast Asia.  The plant did not successfully establish a permanent population in the U.S. until a reintroduction in the late 1930s when a Pennsylvanian nursery germinated Holly seeds from Japan and in doing so, the stowaway mile-a-minute seeds.
Approximate U.S. distribution as of July 2013. Source: Eddmaps.








Mile-a-minute earned its name

Mile-a-minute leaves and ocreae. 
by Leslie J. Mehrhoff
Mile-a-minute is an annual trailing vine with distinctive alternate triangular leaves.  Another identifying trait is the round saucer-shaped structures, or ocreae, which occur at nodes and branching points along the stem.  Self-pollinating flowers and subsequent fruit arise from the ocreae. Recurved barbs along the stem and leaf petioles make this plant particularly unpalatable to most potential herbivores.  Low predation rates in the U.S. coupled with the species’ prolific seed production and readily available dispersal mechanisms (water and birds) are traits characteristic of an exceptionally weedy plant.

Following annual die-back mile-a-minute 
leaves and stems continueto weigh down the 
plants they have climbed & shade groundcover.
by L. J. Mehrhoff via Invasives.org
Most impressing, and most ecologically damaging, is mile-a-minute’s growth rate of up to six inches a day, or 77’ (33.8 m) in a single growing season.  For perspective, mile-a-minute could cover the Statue of Liberty from heal to torch in two growing seasons.  Methods to control this invasive plant include traditional methods of manual removal and chemical pesticide applications.  However, given the rate at which mile-a-minute spreads, traditional methods are not practical of well-established or remote populations.  In 1996, the U.S. Forest Service began researching possible biological control agents.  

Fighting nonnative with nonnative: biological control

Biological control is a way of using an invasive species natural predator or disease, most often from the species’ indigenous region, to reduce the invasives’ proliferation and dominance.  Finding a biological control agent that is truly host-specific to your target species takes a lot of research.  Inadequate research into a control agent’s life history and ecology prior to release may have dire consequences, which are worse than the original cause for their introduction.  A classic example of biological control gone awry is that of Cane Toads introduced to Australia in 1937.  Thankfully, the science of introducing biological control agents has come a long way!

Adult R. latipes are approx. 2mm long.
by Amy Diercks, via Invasives.org
Colpetzer et al. published a study in Biological Control (2004) examining potential biological control agents for use on mile-a-minute.  Results from their study supported the introduction of a small host-specific weevil from Asia, Rhinoncomimus latipes, which feeds on mile-a-minute roots as a larvae and foliage as an adult.  In 2004, the U.S. Department of Agriculture approved the use of the weevil as a biological control agent.  After several regional releases, the introduced weevils have successfully established populations throughout the Mid-Atlantic region. 

Ongoing weevil releases, such as one recently conducted in Union County, New Jersey, help sustain and expand the current weevil populations.  Led by state and county agriculture officials, the recent release of 2,000 weevils in Watchung Reservation, Union County’s largest park, is sure to reduce local mile-a-minute growth in the coming years.

Below is a video from a weevil release in New York City

Amy Diercks, Bugwood.org