By the way, this plant attracts a lot of ants and some kind of insects. This plant has thorns on the branches and stems. As least, I noticed that usually perennials don't have thorns. Only do weeds have thorns.

I have this weed too! Very hard to get rid of. I believe this is horse nettle. If anyone knows how to eradicate it, please let us know!

Simone

Sure looks exactly like the photo of horse nettle (Solanum carolinense) on wikipedia. Scary!

Here is a link that might be useful: horse nettle

You wrote:
"By the way, this plant attracts a lot of ants and some kind of insects."

The "some kind of insects" are aphids. Lots of them. That's why the ants are there. To obtain the sweet sticky honeydew the aphids excrete.

It's horsenettle. Roundup works--eventually. You'll have to repeat the treatment several times. There's a thick root, very deep--sometimes 15 inches down--that you have to exhaust.

Yes, it's horsenettle and it's a real doosey to get rid of once it colonizes. Get rid of it before those seeds mature.

Janet

What ky said! Remember always that blooms mean seeds are close behind. l0 blooms mean l0 million seeds to pull nexty year! Pull that sucker out! Even if you don't get all the root, it beats millions of seedlings (especially thorny ones.)

And, put it in the trash, not the compost pile; I've had similar problems with canadian thistle, and the seeds seem to be able to mature after the plant's been dug up and composted. Yuck.