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Mouse-ear hawkweed

Mouse-ear hawkweed

Mouse-ear hawkweed

(Hieracium pilosella)

Priority: -  Prevent

Tags: Terrestrial

Identification and Reproduction

Identification: 

  • Mouse-ear hawkweed is a perennial herbaceous plant that is low growing, growing up to 30 cm tall. 
  • Stems are slender and hairy. 
  • Leaves occur in the form of a basal rosette or sparsely on stolons. Leaves are flat, narrow and covered in hairs. 

  • Single flowers or pairs are found on the ends of stems. Flowers are dandelion-like with many petals. Bracts are covered in blackish glandular and while bristly hairs.

  • Each rosette will produce one flower head. 
  • Blooms occur in May and June. 

Reproduction: 

  • Plants can reproduce vegetatively or from seeds. 
  • Stolons will stretch and from axillary buds and form daughter rosettes. 
  • Seeds can be dispersed by wind. 
  • Stolon fragments are often spread by agricultural machinery. 

Habitat & Ecology

  • Common on open, sandy and semi-dry sites. 
  • It is found on grasslands, roadsides, pastures and sites that are commonly disturbed. 
  • It is well adapted to soil with low moisture and nutrient levels. 
  • Mouse-ear hawkweed is shade intolerant. 

Impacts

Social:

  • Seeds will often contaminate agricultural seed crops. 
  • Reduce forage availabilty for livestock. 
  • Reduce the quality and value of crops. 

Ecological: 

  • Invades open space quickly and will out-compete native species. 

Management

Prevention is a high priorty for this plant. 

  • Ensure that equipment, vehicles and tools are clean and free of debris. 
  • Considering increasing shade by planting native shrubs and trees.  
  • Promote healthy grass cover by seeding and fertilizing to prevent hawkweed establishment. 
  • Report this plant if you think you have seen it. 

Mechanical/Manual Control:

  • Small, young infestations can be dug up and removed. It is recommended to remove when soil is moist so entire root systems can be removed. 
  • If flowers are present cut off the stem carefully. 
  • Bag and dispose of all plant parts in the garbage. 

Resources

For more for details check out the Invasive Species Compendium datasheet on Pilosella officinarum (mouse-ear hawkweed). 

For more details on how to distinguish and control hawkweed species please check out the King County Best Management Practices for Hawkweeds

Header photo (gailhampshire).