Please help! I have absolutely no idea what the heck this weed is. Over the last 3 years, these big boys resurface in the same place on the east side of my house. Morning to noon sun, loves being near the hydrangeas, grows rapidly, tall, prone to weed killer and bleach, resembles a succulent with thick stalks and hollow, snaps easily, has little clusters of white flowers at the top. I have even dug them up at one point. A couple of months ago I cut them to the base, hollowed the stalk heads out with a screwdriver and poured straight bleach in them and this is what I get back (see pics). It took a bit longer for them to come back...thought I was good for a little while them bam, ugh! Any advice would be appreciated. The only good thing about them is they shade the hydrangeas from getting burned in the Kansas sun, wind, and heat. Thanks! I will have to post pics from the computer as the phone photos are too large to submit.