ragweed

noun3

1. •
   A plant of the genus Ambrosia, native to North America and a common invasive species elsewhere, particularly noted for producing pollen that triggers hay fever.

   • RAGWEED (Jeffogia Fingerolia) : The hayfever king, ragweed, brings tears to the eyes of grown men. — 2009
2. •
   A summer cypress, mock cypress (Bassia scoparia).
3. •
   (Ireland, Scotland) Synonym of ragwort.