Can someone please ID this plant? I would like to know if it is invasive. Is growing in a yard that is not lived in anymore. Surviving winters in Calgary at the highest altitudes here and doing very well. Thanks, Skip
Armenian Basket Flower, Centaurea macrocephala. Very majestic plant if grown in conditions that suit it.
"Plants are not invasive or weedy in the least. . . . Extremely hardy, and a good choice for gardeners in prairie regions." http://www.perennials.com/plants/centaurea-macrocephala.html
This species is very difficult to control once established and is a threat to our natural areas, including subalpine meadows http://www.nwcb.wa.gov/detail.asp?weed=29 There is a 1918 collection from the garden of Wilhelm Suksdorff near Bingen, Klickitat County, at an elevation of 1900 feet. There are two known field locations in Washington. All sites appear to have been originally cultivated as an ornamental species. The site in Pend Oreille County, was discovered in 1981. This site is an abandoned homestead, and C. macrocephala has grown from a few plants to over 10 acres http://www.nwcb.wa.gov/siteFiles/Centaurea_macrocephala.pdf
Location Location Location Since the OP is in Calgary, Alberta this is mostly an Academic Exercise. It's no more likely to be invasive on the opposite side of the Great Divide than it is to be a problem for me in Texas where it won't even grow. That's not to say it doesn't bear watching just that it's altogether unlikely.
Looking at the site it appears to be a blanket prohibition owing to an abundance of caution. I don't subscribe to that mentality as I know different species can behave very differently in the same locality. http://www.edmontonhort.com/gardeningalert/Prohibited.php
See depiction of wild habitat at my second link. If you are thinking the WA infestations are in Pacific Slope conifer forest, you are mistaken. This is a montane prairie and meadow species, Alberta might be quite suitable.
From my research the plant was introduced to the US at least 200 years ago. When thinking about it, not just repeating one after another what someone sometime ago decided to label it with, the presence of only two locations (only one worth talking about http://www.nwcb.wa.gov/siteFiles/Centaurea_macrocephala.pdf ) where it managed to establish itself during this 200 years, only says the opposite, that the plant is not invasive. From my own experience, again, it is the opposite. I had to start it anew myself from seeds I have collected, to replace the old specimen with a new one. It is sad, because I can see so many really bad weeds around that nobody is talking about, not on any obnoxious weeds lists, while a few, what it looks like randomly selected species, face all the prosecution.
