While I don't have a bucket list of weeds, it's always nice to find a new one. Today I had my first encounter with blue mustard (Chorispora tenella). Like all mustards, this plant has four petals, but the petals of blue mustard are pink to purple in color and very narrow, relative to their length. My initial thought was that it might be Dame's rocket since that is another mustard with bluish flowers, but the narrow petals made me go to the books.
I encountered this plant at the entrance to a pasture at one of Animal Science's teaching farms. I suspect it may have been introduced in feed or bedding imported to the farm. Blue mustard is a winter annual and a problem in states west of us. Its life cycle is out of sync with those of corn and soybean, so it shouldn't pose a threat to those crops. It could be an issue in small grains and hay fields, but since it's not a serious weed in the west I suspect it will not be real aggressive at this site. It will be fun to watch over the next few years.