plant-weed? ID.

[Daniel_B]

Hello, I live in the midwest, IL., USA. I was visiting my brother and his family today and noticed a very strange plant I have never seen before growing in one of their outside flower pots. I asked my sister in-law about it and she said it just startd growing a couple of weeks ago and she decided not to pull it out. My other brother who was also there and is an avid gardener said he had never seen this type of plant either. The plant is about a foot high now. It has lots of stems with leaves that, when the sun is on them, open up. When I saw it, the plant was in shade and the leaves were folded up, kind of like a zipper. Each leaf is about a 1/4 inch length. The whole plant is the same color of green. I would say about the same shade of green as a tomatoe plant leaf. Looks like something that would grow in a rain forest. I wanted to do a google search on it, but where to start? Thanks for any info. Dan.

[Jim Shaffer]

Sounds like a mimosa tree. Not genus Mimosa, but I don't remember what it is.

[DrLith]

There are two completely different plants that are commonly known as "mimosa," and it's probably one or the other. Mimosa pudica is a tropical plant native to south america that's often grown as a curiosity ornamental, but I don't know if it would naturalize as a weed in Illinois. This type of mimosa folds up when touched.

The other, Albizia julibrissin, known as mimosa or silk tree, is native to Japan but is hardy to zone 6 and has naturalized around much of the mid-atlantic and southern US. It grows very quickly, spreads easily, and has big fluffy pink flowers in June. This type of mimosa folds up in the evening, but are not as responsive to touch, in my experience.