1. Common North American weed with linear leaves and small discoid heads of yellowish flowers; widely naturalized throughout temperate regions; sometimes placed in genus Erigeron
   "Horseweed sprouted in the untended garden";
   - Canadian fleabane, fleabane, Conyza canadensis, Erigeron canadensis
    
2. Erect perennial strong-scented with serrate pointed leaves and a loose panicle of yellowish flowers
   "horseweed grew tall among the native woodland plants";
   - horse balm, stoneroot, stone-root, richweed, stone root, Collinsonia canadensis

Derived forms: horseweeds

Type of: herb, herbaceous plant, weed

Part of: Collinsonia, Conyza, genus Collinsonia, genus Conyza

Encyclopedia: Horseweed