Over the course of 3 months, these things grew from non-existent to, in some cases, nearly 7 feet long/tall. Mainly growing up the sides of fences and trees/bushes, they have thick red vines, large green leaves, and little white flowering buds. Started with two or three, now there are a couple dozen all along the property lines. No idea what they are, but local landscaper said he wouldn't touch them. Brushed up against one and ended up with large blisters. Not sure if they are poisonous or just had an allergic reaction. Any idea what I'm dealing with?
Pokeweed, Phytolacca americana http://davesgarden.com/guides/pf/go/576/ It's not a vine though, so I wonder if there's something else growing in there that is a vine and could cause that reaction? Pokeweed is poisonous (as in toxic if you eat it, although you can eat the blanched greens when they're young) but I don't know that it would cause blisters, so I wonder if there's something like poison oak/ivy mixed in there somewhere and that's what he rubbed against.
In the 3rd picture there looks something reminiscent of poison ivy in the background on ground/fence, considering the trifoliate leaves, small side leaflet stems, opposite leaflets. Not saying it wasn't the pokeweed though, because plants are different for everyone.
Thanks for the incredibly quick responses! Mine definitely appear to grow more like vines, but the Pokeweed photos are a dead-on match. Blisters were actually mine, not the landscaper's, though I've got a variety of 'mystery plants' growing in close proximity - I may have jumped the gun on blaming the pokeweed that's taking over my perimeter. I'm best with plants when they wear name tags, so I may be back with photos of a couple others the invited themselves over - figure out where that chicken landscaper can start first. :)