"lantern" weeds

Once again I was late getting out of work, so had to resort to another "back yard weed blip". I told my husband that it was obviously a GOOD thing that I haven't weeded in such a long time, as otherwise I'd have nothing to take pictures of! Ha! I found this one way in the back, growing under the lilac tree. Actually, for a weed, I think it's kind of neat, as it has all kinds of these little lantern-shaped things growing on the stems. I tried to look it up online, but only found a question from another person who had them growing & wanted info. on them. They commented that it became very invasive in just a few days. Wouldn't you just know that some highly invasive plant would find it's way into MY yard! (Probably because it was made to feel so welcome by all the other weeds!! Ha!) :)