Fire Weed is a plant that appears in the game, DreamWorks Dragons: Wild Skies.
In the Wild Skies game, fire weed appears similar in shape to grasses.
In reality, there is a plant native to Northern latitudes in North America, Europe, and Asia with the common name Fire-weed (Chamaenerion angustifolium). Other members of the Genus Chamarnerion may also be referred to as fireweeds. Chamaenerion angustifolium is a flowering perennial (comes grows back after winter for multiple years) with reddish stems, lance-shaped leaves, and a spike of small purplish to reddish pink flowers.
There is also a genus of fireweed (Senecio species) native to many areas of the planet in real life.
In the Franchise, Fire Weed is a food to feed certain dragons to help tame them.
In actuality, Chamaenerion angustifolium Fire-weed has been used as food by native peoples. Young shoots can be eaten as potherbs, the roots can be roasted, and the stems eaten raw are a good source of vitamins. As the plant ages and flowers, parts may become bitter, but is not toxic, and planned harvest and preparation can avoid the bitterness. The leaves can also be harvested for tea, and was popular historically as "Russian Tea".
Medicinally, some Native American tribes have used the stem to place on infected wounds to draw out the pus.