Invasive Species column

The OASISS field crew has been kept busy removing invasive plants and also replanting areas with native species.

This past weekend, many people took a moment to contemplate what they are thankful for. So I’d like to take this opportunity to give thanks to everyone who has helped to make a difference to our regional program this year.

Firstly, I’d like to thank the many readers of the “Invasive Species” column who take the time to share their stories, report new sightings and make requests for specific topics. I would like to thank the residents of the Okanagan-Similkameen who are

helping to make a difference by preventing the spread of

unwanted plants and other invasive species. Many of you have requested a presentation to your class, club or association, or you’ve invited me onto your property to provide you with advice or

encouragement. I thank those of you who take the time to stop by our booth at community festivals and fairs with your questions and comments or talk to our summer staff at boat launches.

Thanks as well to our enthusiastic Field Operations Manager Jessica, our hard working summer students James, Tara, Sam, Tess and Carley, our field crew Gerry, David and Sam, and our dedicated Board of Directors. We have made huge strides this year thanks to these people, our funding partners and the many others who recognize the importance of taking action to prevent further spread of invasive species.

Now I would like to give thanks for the weeds we do not have in our region. These are just a few of the world’s worst invasive plants and I think it goes without saying that these are invaders that we want to take all precautions to ensure they never arrive. They are some of the fastest growing, most ecologically destructive plants in the world.

Kudzu is a climbing, deciduous vine capable of reaching lengths of over 30 metres. Preferred habitat includes open, disturbed areas such as roadsides, right-of-ways,

forest edges and old fields. Kudzu often grows over, smothers and kills all other vegetation, including trees.

Kudzu is native to Asia and was first introduced into the United States in 1876 at the Philadelphia Centennial Exposition. It was widely planted throughout the eastern United States in an attempt to control erosion. Now it covers between 20,000 and 30,000 square kilometres of land in the southeast US and costs the economy half a billion dollars a year in lost farmland and efforts to control it. Common names for kudzu include: mile-a-minute vine, foot-a-night vine, and the vine that ate the South.

Water hyacinth is native to South America, but is now widespread in Asia, Africa, North America, Australia and the UK. It was introduced to North America in the late 1800s as an ornamental pond plant. It is a free-floating perennial plant that can grow to a height of one metre. Underneath the water is a thick, heavily branched, dark fibrous root system, while above the water, this invader has striking light blue to violet flowers located on a terminal spike.

Water hyacinth is one of the fastest growing plant species in existence. Populations can double their size in as little as two weeks. If not controlled, it can cover

literally an entire lake or pond. This blocks sunlight, impacts water flow and starves the water of oxygen resulting in fish kills and impacts to other aquatic species.

Another plant that deserves special

mention is Salvinia molesta, an aquatic fern. Originally from South America, it is now scattered throughout the southeast U.S., and is also know to occur in Southern California and Hawaii.

This plant spreads at an alarming rate; it is able to double its numbers every 2.2 days under ideal conditions.

If you consider this doubling rate and add just one plant to a water body, you will have over 8,000 plants within the first month. Equally troublesome is the fact that this fern reproduces as portions break off. This means that if a boat travels through a mat of these weeds there is a good chance that the plant will break into several pieces which each have the ability to grow into new plants.

Also, the plant grows in large, thick mats. Mats of salvinia have been recorded to be as large as 96 square miles in area and up to one metre deep. These mats can block all sunlight from entering the water and as they decay, the plants can cause a decrease in dissolved oxygen in the water body. Both of these actions will severely reduce the habitat available for fish.

Sadly this plant was most likely introduced through the aquarium and landscaping trades, and this continues to be a possible route of infestation. This plant has been sold under many common names including water velvet, salvinia, giant salvinia, African pyle, aquarium watermoss, kariba weed, water fern and koi kandy.

For further information on invasive species go to our website:, Facebook page society or contact Program Manager for the Okanagan-Similkameen, Lisa Scott, at 250-404-0115 or

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