I've got a newcomer to the yard in at least two locations but I haven't
figured out what it is yet.

It's a vine with lots of little thorns on the stem. The leaves are spade
shaped,smooth edged, alternate, mottled green on the top, solid green
underneath. Up to 3" long, about an 1 1/2" at the base ending in a
point. The older leaves are changing to browning green.

Any ideas?

Kate
Zone 6b