I wanted to see what it grew into. It's really a pretty interesting plant, about 6 feet tall with a plume of flowers at the top. These pics are from several years ago and I've discovered this thing is really aggressive if you are stupid and let it grow to full size and spit out seeds. But still, pretty cool looking. I would like to know what it's called and the latin name if possible.
Looks like Conyza canadensis to me. Common names include Horseweed and Marestail. It grows to upwards of 6 feet in one tall stem, before branching to produce many small white flowers which then proceed to produce LOTS of tiny seeds with little white tufts to help it spread in the wind. Leaf shape of your weed appears to match up, long with a few serrations along the edge.
It's becoming an increasingly troublesome pest in agricultural settings because many populations have developed immunity to Glyphosate.