Friday, May 23, 2008

Corky Milk Vine

Secamone elliptica
The delicate tracery of fine branchlets and little leaves on this vine, together with its stunning corky trunk, make it a good potential garden subject. It is very drought hardy, and like to grow in full sun or dappled shade.
Corky milk vines grow in our local dry rainforests and vine scrubs, most often in sites where hoop pines also grow naturally. They have small, star-shaped, yellow flowers (pretty enough, but too small to be classed as decorative), and pointed, pencil-sized seed follicles produced in pairs at the end of hanging stems. These hold themselves horizontally - pointing, between them, at a quarter to three - and are quietly ornamental as they mature from green to brown, then split to let their seeds float away on their silky parachutes.
Mature plants have very attractive, thick, corky bark, with pronounced longitudinal furrows. The stem in the photo is 5 or 6cm in diameter.
They are host plants for the caterpillars of the beautiful blue tiger butterflies, one of the kinds of butterfly which deliberately feed on poisonous plants. Absorbed into their bodies, it defends them from birds.
Our native birds have learned not to eat them, of course, but some birds which have suffered from the milk vine’s poison are ostriches, which have died from eating the seed follicles. It is not likely to be a problem in a garden, but the slender stems do “bleed” white sap if broken. As with all milky-sapped plants, care should be taken not to get it in your eyes.

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