Thursday, February 23, 2012

Barbed Wire Vine

Smilax australis
Considering that they use three climbing techniques, we would expect barbed wire vines to make a better job of it!
They have tendrils, they can twine, and they use their prickles to scramble through nearby vegetation. So why are they most often found in a tangled mess near the ground?
Despite its common name, this plant doesn’t have large barbs. What is does have is lots of scratchy little prickles on its strong, pencil-thick stems. Bushwalkers know it as the plant most likely to trip them as they walk.
The tendrils are botanically interesting. This is our only local native climber with paired ones. They have evolved from stipules, whereas most plants’ tendrils are modified leaves, stems, or flower-heads.
The leaves are large and leathery, and new ones can be showy bright red.

Once a year the plants have a flush of fluffy flower clusters, followed (on female plants) by bunches of berries which ripen to black and are popular food for birds.

This light vine is sometimes recommended for gardens, despite its scratchiness. It would certainly be easy to grow, and can be encouraged to reach a height of 8m. The prickles are small and are irritating rather than injurious, but I can’t see it ever becoming a popular garden plant. It should be nurtured in native scrub remnants, however, because of its value as a wildlife plant.
It is a valuable host for a number of showy little jewel butterflies, as well as for the erebus moth (above).
An alternative common name is “ant vine”, because of a sweet secretion from the leaf tips which attracts those insects. The same ants protect and care for the butterfly larvae.
Yet another “common” name is the misleading “native sarsaparilla”. Commercial sarsaparilla is made from several central American species of Smilax. It was a traditional medicine for rheumatism, whose strange but agreeable taste led to its use as an ingredient in the popular drink. Our local plant has neither the flavour nor any known medicinal qualities.

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