Spotted knapweed (Centaurea stoebe)

Plant Family: Sunflower (Asteraceae)

Identification Guide: *Print version
Phenophase Field Guide: *Print version

2009 Live Map - View

Did you Know? It is difficult to find much written in a positive light about this aggressive, invasive alien weed species. It is thought that spotted knapwood was introduced to the US in the early 1900’s in shipments of alfalfa seeds from Eastern Europe. Most animals do not like to eat knapweed because of its bitter taste. If eaten, it is harmful to their digestive tract. Many people are allergic to the chemicals in knapweed leaves, so always make sure you wear gloves when you hand pull plants. Knapweed is very drought resistant, does well after fire and other disturbances, and has chemicals that actually deter the root growth of native grasses, and can be used as a natural herbicide. Ironically, knapweed has been introduced in some places for bee keepers, since it can flower throughout the hot dry parts of the summer, when most native plants are dormant.

Identification Hints: There are many species of knapweed that have been introduced to North America, four of which are among the worst noxious weeds in the western US. Spotted knapweed is the only one with black tipped involucral bracts (the leaf-like structures that surround the cup upon which the flowers are attached), creating a spotted appearance. The garden plant Batchelors buttons (Centaurea cyanea) also can occur in disturbed habitats. It has smooth involucral bracts and entire leaves, but is not a major weed

Phenological Observations of Interest: First Flower, End of Flowering, First Ripe Fruit, All Leaves Withered

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2009 Live Map for Spotted knapweed

Below you can view the latest 100 observations that have been reported in 2009 for Spotted knapweed (If the map below is empty then there have not been any 2009 observations reported.)

Use the navigation buttons on the left to zoom in/out and pan around. Click on each place marker to get detail information about that observation.

= First Flower
= End of Flowering
= First Ripe Fruit
= All Leaves Withered

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