noun (n)

• widespread European weed with spiny tongue-shaped leaves and yellow flowers; naturalized in United States(noun.plant)

  Synonym:
  bristly oxtongue, bugloss, oxtongue, picris echioides
  

  source: wordnet30
• any of numerous chiefly North American weedy plants constituting the genus Ambrosia that produce highly allergenic pollen responsible for much hay fever and asthma(noun.plant)

  Synonym:
  ambrosia, ragweed
  

  source: wordnet30
• A species of Ambrosia (A. artemisiæfolia); Roman worm wood.(noun)

  source: webster1913