question: What is a genus of North American plants in the aster tribe within the daisy family, Sorbus or Townsendia ?
answer: Townsendia
context: Title: Triniteurybia
  Passage: Triniteurybia is a genus of North American plants in the aster tribe within the sunflower family.
  Title: Petradoria
  Passage: Petradoria is a genus of North American subshrubs in the aster tribe within the daisy family.
  Title: Townsendia
  Passage: Townsendia is a genus of North American plants in the aster tribe within the daisy family.
  Title: Sericocarpus
  Passage: Sericocarpus is a genus of North American plants in the aster tribe within the sunflower family.  Whitetop aster is a common name for the genus.
  Title: Toiyabea
  Passage: Toiyabea is a genus of North American plants in the aster tribe within the daisy family.
  Title: Xanthocephalum
  Passage: Xanthocephalum is a genus of North American plants in the aster tribe within the sunflower family.
  Title: Pityopsis
  Passage: Pityopsis is a genus of North American plants in the aster tribe within the sunflower family.  Species of "Pityopsis" are known by the common names silkgrass or golden asters or grass-leaved goldenasters .
  Title: Psilactis
  Passage: Psilactis is a genus of North American and South American plants in the aster tribe within the sunflower family which are known by the common name tansyaster.
  Title: Rigiopappus
  Passage: Rigiopappus is a genus of North American plants in the aster tribe within the sunflower family.  It is closely related to genus "Pentachaeta".
  Title: Sorbus
  Passage: Sorbus is a genus of about 100–200 species of trees and shrubs in the rose family Rosaceae.  Species of "Sorbus" ("s.l.") are commonly known as whitebeam, rowan, service tree, and mountain-ash.  The exact number of species is disputed depending on the circumscription of the genus, and also due to the number of apomictic microspecies, which some treat as distinct species, but others group in a smaller number of variable species.  Recent treatments treat "Sorbus" in a narrower sense to include only the pinnate leaved species of subgenus "Sorbus", raising several of the other subgenera to generic rank.
citations: Townsendia Sorbus