The Sollya genus has only three species. Sollya belongs to the pittosporum family (Pittosporaceae) and is closely related to Billardiera. The plant is endemic to southern Western Australia although it is established as an invasive weed in parts of South Australia, Victoria and Tasmania. The name is in honour of naturalist, Mr R H Solly.
Generally the leaves are elliptical in shape and dark green in colour. The stems twine themselves round anything that will act as a support including other plants, trellises or fences. As one of few blue-flowering Australian native plants, the sollya has endeared itself to gardeners by its star-shaped, bell-like flowers. As well as blue, sollya flowers may be pale pink or white. Flowering occurs in summer.
Sollya heterophylla (also known as Sollya fusiformis or Australian Bluebell Creeper) is a hardy, twining climber, relatively dense in habit. It is also sometimes called Billardiera heterophylla.
Its natural habitat is the forests and woodlands of southern Western Australia. The stems vary from coppery brown to grey. The leaves are 20 to 50mm long and 5 to 15mm wide. They are a mid to dark green with a prominent mid-vein and a lighter undersurface. Clusters of intense blue bell-shaped flowers hang from the tips of the branchlets mainly from September to February. The flowers have 5 petals and are around 1cm in size, occurring in drooping clusters of 1 to 5.
Cultivars include S.h.parviflora which has smaller flowers of a deeper blue. S.h.Alba has creamy white flowers. It is a hardy species, adaptable to a wide range of conditions. It responds well to pruning.
The flowers are followed by elongated green fruits which turn to purplish-green as they ripen. Each fruit contains over 50 seeds. The seeds are spread by birds, foxes and, potentially, possums and other small marsupials. Following bushfires or disturbance of the soil, there is prolific regeneration of seedlings.
This species often looks sparse when first planted but thickens up as it becomes established.
To provide an attractive display of flowers, Sollyas need a position with full sun. They need well-drained, fertile soil if they are to thrive. New plants can be propagated from fresh seed during spring or from cuttings from soft wood in late summer.
Over the last half century or so, Sollya has been widely cultivated as a decorative garden plant. It has escaped into some areas, usually those receiving over 550mm of rainfall per annum, and is now causing significant environmental problems as an introduced weed. It tolerates light frosts, partial shade and is drought resistant. It may smother native species of flora and impacts on native fauna by changing the natural habitat.
