Cardiospermum grandiflorum (SAPINDACEAE) Balloon Vine

Native to the tropical areas of Asia, Africa, and America, Balloon vine is a major problem in the catchment. It can easily take over neglected and disturbed creek habitats and produce screens of foliage blocking out light needed by native plants. It spreads easily and smothers trees, completely taking over the canopy. Stems are ribbed and covered with hairs, particularly when young. Small specimens are relatively easy to remove, but larger mature vines often reach 1 cm in cross section and by then they almost certainly have produced seed, which can persist in the seed bank for up to 11 years. Not noxious in Queensland but declared in New South Wales. Its status is currently unassessed in Western Australia and it is therefore prohibited entry until a weed risk assessment has been carried out.

Leaves are compound, alternately arranged with leaf stalks (petioles) to 3.5 cm long. Leaflets arranged in three groups of three (i.e., biternate). Leaflets are hairy, pointed at the tips and have a toothed (serrated) margin.

Some research on biological control is being undertaken by Carroll-Loye, a biological research company operating out of Davis California. By training the local soapberry bug Leptocoris tagalicus to feed on the Balloon Vine, it is possible that the spread of this vine may be slowed by companion planting of native host plants such as Alectryon tomentosus.

Flowers are white, 4-petalled, clustered on stems (peduncles) that can be from 5 to 30 cm in length and possess two tendrils near the apex, from summer through to winter.

The fruit are large inflated, balloon-shaped, ribbed capsules covered in small hairs. They are green initially, turning straw-coloured and darkening with age. Seeds are rounded and black in colour (about 7 mm long). Balloon Vine propagates readily from seed. Another closely related species is small balloon vine Cardiospermum halicacabum. Balloon vine Cardiospermum grandiflorum can be distinguished from small balloon vine Cardiospermum halicacabum by having larger leaves, capsules and flowers (petals 9 mm long versus 4 mm long).