This coarse, homely American weed is an annual and derives its name from its habit of growing freely in moist open woods and clearings, and in greatest luxuriance on newly-burnt fallows. It has composite flowers, blooming from July to September.
Lactuca Canadensis, the wild Lettuce or Trumpet Weed, and Hieracium Canadense, are also given the designation of 'Fireweed' in America from their habit of growing on newly-burnt fallow, but Erechtites hieracifolia (Rafin.) may be called the true Fireweed, as it is the plant which commonly goes by that name.
Senecio is derived from Senex (an old man), in reference to the hoary pappus, which in this order represents the calyx; Erechtites comes from the ancient name of some troublesome Groundsel.
Fireweed is a rank, slightly hairy plant, growing from 1 to 7 feet high. The thick, somewhat fleshy stem is virgate, sulcate, leafy to the top, branching above, the branches erect. The leaves are alternate, delicate and thin, very variable in size and form, lanceovate to linear, apex-pointed, margins irregular, sharply toothed, or divided right down to the midrib into leaflets, which are sometimes then bipinnatifid, the lower, very short-stalked and becoming sessile as they grow up the stem. The flowers are white or yellow, a corymbose panicle. The little fruits are oblong, slender, tapering at the end, striate and crowned with a very fine copious silky pappus, white or violet. The whole plant is succulent, the odour rank and slightly aromatic, with a bitterish and somewhat acrid and disagreeable taste.
In the United States Fireweed is a very troublesome weed; the fields often get infested with it, and when growing among Peppermint, it is definitely destructive, as it gets mingled with the plant in distilling and causes great deterioration of the oil.