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Pilosella officinarum
Also called Mouse Eared Hawkweed
A low, hairy perennial with a basal rosette of leaves and single lemon-yellow flowerheads on stems up to about 50 cm tall. It spreads by stolons into dense mats, and it is grown mainly as a hardy garden or ground-cover plant in dry, sunny spots with poor soil.
Pilosella officinarum (synonym Hieracium pilosella), known as mouse-ear hawkweed, is a yellow-flowered species of flowering plant in the daisy family Compositae (= Asteraceae), native to Europe and northern Asia. It produces single, lemon-coloured inflorescences. Like most hawkweed species, it is highly variable and is a member of a species complex of several dozens of subspecies and hundreds of varieties and forms. It is an allelopathic plant.
Mouse-ear hawkweed has become a common introduced invasive species in North America (where it is found in southern Canada and both north-east and north-west United States), and New Zealand. It is a level C noxious weed in the United States (with higher levels in the states of Washington and Oregon), and a weed in Quebec. It does not have special designations in other locations in Canada. It is known to be strongly invasive in New Zealand's tussock fields, where there are no native species of hawkweed, and biological control measures are being undertaken to control it and other similar species. In Victoria and NSW, Australia, Hawkweed Sp. are declared as State Prohibited Weeds and are controlled under The Bio Security Act 2015. Currently there are several eradication programs operating (often employing volunteers) to locate, prevent the spread of and eradicate any Pilosella (Hieracium) sp. plants.
Joseph Pitton de Tournefort mentions that blades covered in this plant's juices were believed to cut through stone as easily as through wood.
It is a known allelopathic plant, whose roots secrete several substances inhibiting root growth, including its own. It can be controlled through rotation with clover and grasses where possible.
Text excerpted from the Wikipedia article Pilosella officinarum by its contributors, under CC BY-SA 4.0; the excerpts and the care summary drawn from them are shared under the same licence.
The care summary was written by AI (Claude, Anthropic) from the sources on this page, with general growing knowledge where they are silent. Check before relying on it.
Life form, climate and native range: World Checklist of Vascular Plants, Royal Botanic Gardens, Kew (CC BY 3.0), reformatted; see Plants of the World Online.
