Duplicate thread with suggestions so far. Previous question didn't mention the neighbour's vine. This makes a Passiflora more likely. We could do with a graphical location to help get an id.

Passiflora foetida? Floral, it's duplicate, because I encouraged him to post it here. We are following your tip. I grew a beautiful passion vine once, and it bloomed gloriously, but it never reached a flowering stage in the following couple years. It would just send up suckers that never grew tall, they were just like the ones in OP's photo.

Passion vine. It is a thug in southern regions. Should be grown in a pot with a saucer underneath.

If neighbor planted it for the flowers, am guessing it's a cultivar (or hybrid) of Passiflora incarnata since it's probably the most common hardy 3-lobed-leaf species. Also tends to be a bit larger and a more assertive root spreader than P. lutea, a smaller flowered and bit less hardy U.S. native. Pretty certain P. foetida does not do well (as a perennial) as far north as OP's NE Oklahoma location.

Lots of other non-native species in the genus, but not many reliably winter hardy into your zone. P. caerulea cultivars (hybrids) are fairly common exceptions that may show some 3-lobed-leaves, but a portion to all of the mature leaves will usually have 5 lobes. I've heard it can be even more "assertive" than P. incarnata.

Could help to see a mature leaf off of the neighbor's vine as the lobes on your young shoots may not be representative.

Whatever it turns out to be, agree it appears to be among the plants that should not be used on a shared fence-line without an effective root barrier/container or some sort of maintenance agreement with the neighbor.

*Sigh* Wish I could get Passiflora incarnata to grow here. My zone 6 is a little to chilly for it and I've not succeeded even in my warmest microclimate. Ah well, with global warming all I have to do is wait.

from the other post: our neighbors have a ferocious vine growing on their side of our fence
and we think it’s from their vine. We’re good friends so we’re going to
talk to them about removing it.

==>>> imo ... there is only one option .. kill it at the source ....

obviously .. its hyper aggressive ... with an incredible root mass .. mowing wont stop it. lawn spray isnt going to kill the root mass .. and every time you knock down one sprout.. 4 to 6 weeks later ... it is replaced ... and the more mature the root mass gets.. the more that will come ...

imo.. your only option is to destroy the mother plant.. use a stump killer.. and spend a year or 3.. killing every sprout.. until the root mass dies ...

you can either volunteer to dig it up .. pay to have it removed .... or move .. lol ... since you claim they are good friends.. it sounds like it can be worked out ...

once the mother is killed.. you can obtain the applicator at the link .. and fill with stump killer or undiluted round up [which is labeled as a stump killer] ... and snip each sprout and apply one drop of killer.. for as many years as it takes.. to kill that root mass .. do not store near the hot dogs ... the key is.. one drip .. and if you knock over the applicator... it doesnt all run out ... IT IS NOT A SPRAY THING.. BESIDES THE FACT THAT YOU WILL KILL ALL THE GRASS WHERE YOU SPRAY ....

ken

https://www.google.com/search?q=plochmans+mustard&oe=utf-8&aq=t&rls=org.mozilla:en-US:official&client=firefox-a&um=1&ie=UTF-8&hl=en&tbm=isch&source=og&sa=N&tab=wi&ei=XQTcUYCCC_OFyQGCg4DAAg&biw=1154&bih=805&sei=XwTcUbmZHZK4yAHD0oDYDw

Matts' Mom,

I hate to give you bad news, because I know this is not fun. However, all rooted sections are "sources". There is no one, single source once it has runners. If you have ever seen passion vine - and you are now, it spreads rampantly by runners - all of which have roots - and all become sources of more underground runners. You need to pull them all at once and then remain vigilant as new ones pop up (and they will, for awhile).

I am a long-time Florida gardener and have dealt with this menace. Best of luck to you! It won't take that long if you keep removing the sources of photosynthesis (stem, leaves, vine), which provides the plant with energy. Just keep on it for a year or so.

Carol

As long as you keep them mowed, you will eventually win (if all are mowed). I have passionflower in my yard (yes I planted it), and I mow it...and it at least keeps it in control (so far).