These plant have reached a height of about 24" by May 20th.
Young seedlings look like this.
The dead seed heads are over 10 ft high
Close up of the stem
There are a lot of plants in this small corridor
see if you can see the young rabbit just to the left of the flower pot
medium sized juvenile plant
Roundup or glyphosate can be used to treat this noxious weed.
Pulling or cutting can also help but beware of getting plant juices on your skin. The sap can leave nasty burn marks, itching, rashes and worse.