Opulent Olax may wear out wattle

Back in September I encountered this shrub next to a jetty on the ocean side of Nornalup Inlet, just south of Walpole, in south-western Western Australia. About here, with South to the North...

I had reached the jetty, and the shrub, thanks to Gary Muir's WOW Wilderness ecocruise. The cruise was both wow and eco-, because Gary (pointing above) is an exceptional host.

Olax phyllanthi, my jetty-side shrub, was identified for me by Steve Hopper, also on the cruise, and now an inhabitant of this region. Lucky Steve.

It's a partly parasitic plant in the olive family, Olacaceae. We have 12 (or perhaps 11) of the world's 60 species of Olax in Australia, with half of these native to Western Australia. In Victoria we have one, Olax stricta, in the far east of East Gippsland.

The genus also grows in tropical Africa, Madagascar and 'Malesia' (north of Australia). Not a distribution entirely aligned with the breakup of our great southern land, Gondwana, but I can't resist this picture of Gary Muir explaining the separation of the continents (with the red peg on the back of some stuffed marsupial being New Zealand, attached to Australia).

Olax might sound a little like Olea, the genus name for the olive we value so much for cooking, nibbling and salad-dressing but olax means 'evil smelling' in Latin, I gather the name applies more accurately to some of the Asian species.

Our species, phyllanthi, is presumably a reference to the leaves, which are arranged a little like some of the species of Phyllanthus (that genus name itself means leaf-flower, because the flowers are produced on the edge of the leaf-like 'phyllodes').

As you can see, Olax phyllanthi grows on sand dunes near the cost. It's quite common from the far west corner of WA through to Esperance.

While the flowers are not particularly conspicuous, the weeping habit and soft, pale green colour of the leaves are definitely attractive. Or perhaps it was sea, the sun and the scintillating commentary from Mr Muir.

Our shrub isn't fussy about its host and will attach itself to the roots of various grasses and woody plants to extract water and nutrients. One well studied relationship is between it and local wattles (you can see one next to the plant I photographed, in the top picture) with their own nitrogen-fixing bacteria living in root nodules.

The Olax soaks up a lot of nitrogen from the host wattle, which then produces more root growth, and more nodule potential, to make up the difference. This all constrains the growth of the wattle due to more resources going into the roots.

All good for Olax phyllanthi though, allowing it to grow in a place with this view (as I swing the camera around 180 degrees)...