Madeira Vine (Anredera cordifolia) is a South American invader with bright green fleshy leaves and tubers growing both underground and at nodes along the trailing stems. There are numerous patches within the Hundred Acres reserve. The first photo is of a new patch heading up the nearest tree.
Once established, manual control is a painstaking task that must be repeatedly frequently to remove freshly sprouted bulbils before their tendrils generate strings of new ones. Also, it is very easy to mistake the worthy native spinach Tetragonia for Madeira Vine. In the second photo, a spinach is peeking out from the Madeira vine near the stick.