Will my beautiful garden flower become a crazed invasive weed?

At the Wyoming Weed and Pest Fall Conferece in Casper this week we spent some time discussing how many of our problematic invasive weeds were intentionally introduced as ornamentals. The introduction of new ornamental species into the U.S. is quite strictly regulated, so there is a good layer of defense from new invasives at the national level. Several researchers have devised schema for assessing the probability of ornamental-turned-weeds to be problematic in a new area. Pheloung et al. 1999 developed a Weed Risk Assessment model for potential introductions into Australia, and with a few adjustments, similar principles may be applied to plants here in wonderful Wyoming. As part of our Invasive Plant Ecology course, Tim Collier and I developed a quick spreadsheet that allows anyone to enter responses to the Pheloung et al. WRA and determine if a plant is likely to be invasive in our area. If it scores <1 its characteristics and history do not indicate it will become invasive in Wyoming. If your plant scores >6, the model indicates there is a likelihood it will be invasive. If it scores between 1 and 6 it falls into a grey category where further evaluation or more information is needed.  This model is not 100% accurate and should probably not be used for any kind of regulatory action, etc., but it gives us a good idea of which plants we plant today we might try to control in the future.

Might your flower garden be a weed patch in waiting? Check here 

Instructions are relatively straightforward. Provide an answer for each question or characteristic in the Answer column (answers will either be yes, no or a number). Answer as many questions as you are able to answer based on your own knowledge of the plant or from other reports you can find. The numeric score based on your answers will be calculated within the excel sheet for you and the OUTCOME will be either ACCEPT as non-invasive, EVALUATE if more information is needed or REJECT if the plant has a high probability of becoming invasive.


  1. how do i get rid of a weed it is very aggressive and has little pink flowers i can fill a garbage bag everyday climbs up my flowers and shrubs in a choking manner tks in advance

  2. Beryl – would it be possible for you to take a photo and email it to us? If we can positively identify your pink-flowered weed, we should be able to provide a recommendation. It certainly sounds like a troublesome weed in your landscaping!

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