You can check Calyptocarpus vialis, but that one may be a miss. We need better photos of the flowers, and some kind of scale.

Are you absolutely certain the flowers are connected to the leaves and not another plant growing amongst them? The yellow flowers look like a Lactuca or Lapsana but the leaves don't fit.

That reaction would be a good argument for the use of Roundup.

You can apply it with a paintbrush to avoid touching the plant, and so one does not harm valuable ornamental plants with the herbicide.

You are absolutely right floral! I followed the stem of the yellow flowers and it was not attached to the evil weed in question. I am getting more pictures.

I added a bright pink pen for reference, this one happened to be growing in my kalanchoe planter. They go from the small size like picture 1 to the bigger size very quickly.

All of these plants were recently repotted with new bags of potting soil and all of them now are just full of these things. I have a feeling it was in the new soil.

Could it be Quickweed?

Oh dear that looks like it might be the correct answer. I looked closely and do see some have those ball looking flower pods. I read some people had serious rashes from them.

from the University of Alabama extension page on this weed:

"The flowers appear as tannish, pea-sized clusters at each node. Unfortunately, mulberry weed is in a hurry to produce seed, so flowers usually appear when plants have only three leaves on them. Plants 2 inches tall are capable of producing copious amounts of seed. Larger plants that get missed in the weeding process produce a truly scary amount of seed.

According to one source, the seeds are explosively discharged and spread up to 4 feet from the original plant.

The first line of defense against this pestiferous weed is to learn to identify it. Then, dispatch it post haste to the trash bin. This one does not go in the compost heap because my pile never gets hot enough to kill seeds. Be sure to pull it before the seeds mature, which in landscape beds, is most concentrated in September and October. Because light is needed for germination, one study found that a 2-inch layer of mulch gave good, but not complete, control.

Chemical weed control is easy using any of the direct contact herbicides,"

It should not be necessary to use any chemicals to rid pots of unwanted plants, just pull them out of the pots. If you don't want to touch the unwanted plants, put a plastic bag over your hand and arm to pull, or use a disposable glove.

Thanks for the ID Carol!

I can't even get near enough to pull because the scent that it gives off as soon as touched sends me into an asthma attack. I start coughing and gagging and can't breathe. I have never had that kind of reaction to any plants. My husband and neighbor will attack the atrium this weekend. It has spread through out the atrium. I feel sure after reading about this pest it came in the new bags of potting soil. Most reported they got it from mulch or soil. Very unfortunate.

Thanks

It has become a common weed in nursery containers.

Raven, in that case, it sounds like you would need a whole plastic bubble! Hopefully a friend or family member can yank them for you, and soon.

I'm surprised to read this discussion because so many of my "house plants" can give me a rash, I get poison ivy, and seem generally susceptible to having issues with plants, but I can pull & be around this weed without problems. I really dislike it because it can't be left to grow to a decent size to add mass to compost before being pulled because it starts makings seeds so quickly. I'm sorry it's giving you trouble and affecting your enjoyment of your potted plants.