Invasive Species Council of Manitoba

Hieracium aurantiacum

Orange Hawkweed is a perennial that was introduced from Eurasia as an ornamental. Infestations usually originate from seed but the plant is also able to reproduce vegetatively by sending out stolons (runners) during the flower stage. These stolons extend 10-25 cm away from the parent plant and produces new roots which in turn produces new plants. Orange Hawkweed forms dense mats that exclude all other vegetation.

It is adapted to a wide range of temperatures and can grow in gravelly acidic soils, full or part sun and can grow under

coniferous forest canopies but it does require well drained soils. Native Hawkweeds in North America don't produce stolons and their flowers are yellow or white.

Stems are leafless with bristly hair, 15-90 cm tall and produce a milky sap. There can be one to several stems per plant. Basal leaves are also covered with hair and are 10-15 cm long. The petals on the flowers

are squared edged, notched and orange-red in colour. There can be 5-30 heads at the end of one stem.


Early detection is the best chance of eradication, once established it is impossible to control.

 

Information provided by the Alberta Invasive Plant Council


Resources

2011 Rural Municipality Distribution Map

2010 Rural Municipality Distribution Map

Orange Hawkweed MWSA 2009 Survey Map

Orange Hawkweed ISCM Fact Sheet

Alberta Invasive Plant Council Fact Sheet

 

Back to Terrestrial Invasive Species List

 





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