Orange Hawkweed

Photo by Ed Oliveras
Photo by Ed Oliveras

The tight clusters or orange, dandelion-like flowers at the end of a leafless stem make orange hawkweed (Pilosella aurantiaca) an easily recognized plant. A native to northern and central Europe, it was introduced as an ornamental to Vermont before 1875. It has escaped cultivation many times and is now naturalized across the northern half of North America. It occurs in a wide variety of habitats and is especially suited to disturbed sites.

Orange hawkweed can form dense mats and crowd out native species. It is one of the six known pollen allelopathic plants. Pollen allelopathy occurs when the pollen of one species is transferred to another species. The transferred pollen then releases toxins which interfere with the growth of pollen tubes, the receptivity of the stigma or style, respiration, germination or growth of the seedling, production of chlorophyll in leaves, or production of seeds.

Though not controlled by the state, orange hawkweed is considered a noxious weed in Carlton, Cass, Itasca, and Koochiching Counties.

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