I was on a local property in central Austin this summer, when I was introduced to a new invader to our town. At first I had no way to identify this vine. No one knew about it, and there were no seedpods or flowers to help identify it. Local inquiries amongst my peers led me nowhere, so I had to do a little extra legwork.
This vine was located on a slope and down into a riparian shady area with a year- round stream. It was located in shady and sunny areas, and was climbing up everything, from shrubs to trees and even a utility pole.
It turns out that the vine can be easily identified by looking closely at the three claw-like appendages that stick out from the center rachis in between each pair of oppositely-spaced paired leaflets along the vine itself. This is what gives it the common name of “Cats-claw vine” or “cats claw ivy” ,Macfadyena ungis-cati.
Additionally, this South American vine grows large tubers below the ground throughout its root system. These have to be pulled out or the vine will re-grow from these tubers. Other than that, the vine spreads from tubers or from flat seeds that form in very long, glossy green seed pods up to 20 inches long!! These pods turn dark brown at maturity and have very long oblong seeds.
The vine will flower in late spring or early summer if conditions are right, forming very large yellow trumpet-like or bell-shaped flowers up to 3 inches long and 4 inches wide! However, this vine does not flower and fruit every year, making identification more difficult for those not familiar with this exotic pest.
This vine is also hardy to 20 degrees, which means the mild Austin winters will only defoliate it at best most winters. Harsher winters might knock it back to the ground where it can still re-grow. In the US, it has invaded Florida and the southern states, and has now made it to Austin. It is devastating to forests in Australia. There is no chemical control for it, and pulling it out by the roots seems to be the best way to keep it at bay. It can also climb anything, and get up to 50 feet into the air.
I have attached pictures to help with identification. If you see this vine on your property, pull it up at once and try to get out the roots and the tubers as well!