Nancy Was Right All Along

My wife has often told me I'd better trim those brambles before they droop to the ground, else they'd take root again.
While I'd certainly heard of plants doing that, I thought that was only in exotic far away places, Baobab trees or something. So I put it to the test and let the brambles go.

Fast-forward to this morning.
Imagine my surprise to find conclusive evidence that she was right all along!
Several of the droopy ends looked like they were trying to burrow into the grass, but then I pulled this one up and became a true believer. Again - this is the part that was formerly reaching for the sky.

 

I see multiple telling factors too:

 1) Roots at the end of two branches.

2) Direction of the thorns points toward the original root, not the secondary root.

3) Tufts on what was the upper side of the leaf stem.

I bet you awready knew about this too.

I've always called these brambles, don't know what a botanist would call the plant, any ideas?