Fireweed
Chamaenerion angustifolium (Epilobium angustifolium)

Family: Evening Primrose (Onagreaceae)
AKA: Giant Willowherb, Cottonweed
Photo taken on: July 14, 2010
Location: Taylor Reservoir, GV, CO
Life Zones: Montane to subalpine
Habitat: Openings, disturbed soil

Grows to 3ft in dense patches, often in recently burned or logged areas and along roadsides. Showy flowers produce seeds with a cottony parachute.

Flora of North America reference.