POWO appears to be mistaken in placing Hieracium horridum in genus Pilosella. Hieracium horridum is endemic to western North America (California, Oregon, Nevada). All of the references I have been able to find online agree that Pilosella is an old world genus which is represented by several exotic and invasive species in North America.
Current regional floras covering the area where Hieracium horridum is found all agree on placing it in genus Hieracium. These floras do also place invasive species in genus Hieracium, but note that others consider them to be part of genus Pilosella.
Los desacuerdos no intencionados ocurren cuando un grupo padre (B) se adelgaza al cambiar un grupo hijo (E) a otra parte del árbol taxonómico, provocando que las Identificaciones existentes del grupo padre sean interpretados como desacuerdos con las Identificaciones existentes del grupo hijo cambiado.
Identification
La ID 2 del taxón E será un desacuerdo no intencionado con la ID 1 del taxón B después del intercambio de ancestros
Si el adelgazamiento del grupo padre provoca más de 10 desacuerdos no intencionados, deberías dividir el grupo padre después de intercambiar el grupo hijo para substituir las identificaciones existentes del grupo padre (B) con identificaciones con las que no esté en desacuerdo,
POWO appears to be mistaken in placing Hieracium horridum in genus Pilosella. Hieracium horridum is endemic to western North America (California, Oregon, Nevada). All of the references I have been able to find online agree that Pilosella is an old world genus which is represented by several exotic and invasive species in North America.
Current regional floras covering the area where Hieracium horridum is found all agree on placing it in genus Hieracium. These floras do also place invasive species in genus Hieracium, but note that others consider them to be part of genus Pilosella.
Flora of North America (2006) http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=250066944
Jepson eFlora (2012) http://ucjeps.berkeley.edu/eflora/eflora_display.php?tid=3509
Oregon Vascular Plant Checklist (2017) http://www.oregonflora.org/family_treatments/Asteraceae.pdf
Flora of the Pacific Northwest (2018)
Bräutigam & Greuter (2007) A new treatment of Pilosella for the Euro-Mediterranean flora https://www.bgbm.org/sites/default/files/documents/wi37-1Braeutigam%2BGreuter.pdf
Gaskin & Wilson (2007) Phylogenetic Relationships Among Native and Naturalized Hieracium (Asteraceae) in Canada and the United States Based on Plastid DNA Sequences https://www.cals.uidaho.edu/hawkweed/pdf/Gaskin%20Wilson%20phylogeny%202007.pdf
Moffat et al (2015) Morphology delimits more species than molecular genetic clusters of invasive Pilosella https://bsapubs.onlinelibrary.wiley.com/doi/pdf/10.3732/ajb.1400466
Wilson (2007) Key to Identification of Invasive and Native Hawkweeds (Hieracium spp.) in the Pacific Northwest https://www2.gov.bc.ca/assets/gov/environment/plants-animals-and-ecosystems/invasive-species/publications/key_to_identification_of_invasive_and_native_hawkweeds_in_the_pacific_northwest.pdf