The Collaborative International Dictionary of English v.0.48:

Rosebay \Rose"bay`\, n. (Bot.)
      (a) the oleander. [Obs.]
      (b) Any shrub of the genus Rhododendron. [U.S.]
      (c) An herb (Epilobium spicatum) with showy purple
          flowers, common in Europe and North America; -- called
          also great willow herb.
          [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Willow-herb \Wil"low-herb`\, n. (Bot.)
   A perennial herb (Epilobium spicatum) with narrow
   willowlike leaves and showy rose-purple flowers. The name is
   sometimes made to include other species of the same genus.
   [1913 Webster]

   Spiked willow-herb, a perennial herb (Lythrum Salicaria)
      with willowy leaves and spiked purplish flowers.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Fireweed \Fire"weed`\, n. (Bot.)
   (a) An American plant (Erechthites hiercifolia), very
       troublesome in spots where brushwood has been burned.
   (b) The great willow-herb (Epilobium spicatum).
       [1913 Webster]