Balloon vine (Cardiospermum grandiflorum)
Balloon vine (Cardiospermum grandiflorum )
A large climber with compound leaves consisting of 9 leaflets arranged in groups of 3, with each leaflet coarsely toothed. The stems, leaflets and leaf stalks are finely hairy, particularly the new growth. Flowers are white, about 1cm across, with 4 petals, and carried in dense clusters on a long stalk in the axil of each leaf. At the base of each flower cluster is a tendril, which balloon vine uses to climb. The fruit is a papery capsule, ripening from green to straw coloured in autumn. It splits into 3 segments, each containing a single black seed.
Preferred habitat and impacts:
Only found in the northern part of the region, from the Illawarra northwards. It prefers moist soils and will tolerate occasional flooding, so it is often found along creeks. It will tolerate some shade but is most vigorous in full sun.
Balloon vine can smother and kill trees, shrubs and groundcover plants.
The light papery capsules float in water and are transported by wind. Seed is only viable for 18 months or so.
Small balloon vine (Cardiospermum halicacabum) is very similar, but smaller and non-hairy. It is only known to be naturalised around Sydney to date.
The native vine, slender grape (Cayratia clematidea ) also has tendrils, and similar compound leaves with only 5 toothed leaflets. Its flowers are very small and greenish, in clusters, and fruit is a small blackish berry. It grows in moist forest and rainforest north from Nowra.
Two more native vines, clematis or headache vine, or old man’s beard (Clematis glycinoides and C. aristata ) have leaves composed of 3 leaflets. These may have toothed edges or not, and may have silvery markings on the leaf, particularly as seedlings. They have white flowers with 4 long thin petals, which are conspicuous in early spring. The small black seed has a fluffy "parachute" of hairs attached. C. glycinoides has thin textured leaves, while those of C. aristata are thicker and slightly fleshy, and its flowers are bigger. Both climb by twining their leaf stalks around their supports.
Hand-pull or dig young plants, or spray larger plants. Alternatively cut plants at the base, leave top growth to die off in place and dig out the root. Cut and paint or scrape and paint very large plants. Because of the short viability of seed, balloon vine infestations can be eradicated in a couple of years if regrowth is monitored and there is no seed source for further infestation located upstream.