when plants go wild?

I was told of a crop planted near a relatives house yrs ago. i have a feeling if they do grow back on their own that after a season would they jsut die off or worse a male grow an ruin everything. so i guess my question is , is it possible that a crop left to its own what would happen to it? thanks its prob a newbie question but u never know

in the mid-west there are wild plants growing in the ditches (hence the name ditchweed). the males and females grow side by side and the flowers are full of seeds. they say that they are a throwback from when the government was growing hemp for ww2...there's no sense smokin it tho cuz it's only like 2% thc.