South Africa
Cape-ivy is an herbaceous vine with a woody base that grows as a perennial from stolons, rhizomes, and very shallow roots. Vines grow up to 20 ft (6 m) long, and stems are typically green but may be purple. Leaves are alternate and ivy-shaped with 5–9 sharp lobes. Leaf blades are up to 3 in (8 cm) long and wide. One form of Cape-ivy produces two small, kidney-shaped stipules at the base of the leaf; the other form does not. Flower heads occur in tight clusters from vine tips and nodes. Each flower head has 10–12 tiny, yellow, and tubular florets. Each floret produces a single cylindrical and ribbed seed topped by a tuft of fine hairs.
Cape-ivy forms dense mats that smother, shade out, and prevent the germination of native and more desirable species. Dense infestations can even break shrubs and trees. Cape-ivy is known to reduce plant diversity, which is expected to have negative impacts on insects and other animals that depend on them. Dense Cape-ivy mats reduce nesting habitat for shorebirds, and the plant contains compounds toxic to humans, other mammals, and aquatic organisms, reducing forage quality and stream health. Cape-ivy also has a shallow root system, leading to increased erosion in riparian areas the weed has invaded.
Moran, P.J. and S.L. Portman. 2022. Cape-ivy (Delairea odorata): History and Ecology in North America. In: R.L. Winston, Ed. Biological Control of Weeds in North America. North American Invasive Species Management Association, Milwaukee, WI. NAISMA-BCW-2022-17- CAPE-IVY-P. https://bugwoodcloud.org/resource/files/23202.pdf