#1325 - Jacksonia floribunda - Many-flowering Stinkwood
Also known as Holly Pea.
This native stinkwood grows up to 5 meters tall, and from Perth up to Three Springs. It was one of the plants in the Alison Baird Reserve that the other insect people and I were checking for insects, but we didn’t find much. Interestingly, those aren’t leaves - they’re flattened and very pointy branches.
But the other reason I’m showing you this is to show just how dense the flora in the reserve is, and in each area much of the vegetation grows to a particular height and stops dead. That’s probably because the claypan just under the sand puts hard limits on growth, but the fact that the soil in the reserve is the Worst In The World can’t help. I’m not kidding about the soil either - most Australian soils are poor in essential nutrients like phosphorus, and the sand here is so atrocious, almost completely lacking, that it’s a wonder anything can grow at all.
Of course, there’s a trick to it. Many Australian plants have evolved Cluster Roots, finely branching rootlets that secrete acid, liberating just enough phosphorus that the plants can grow. They also make some Australian plants very vulnerable to phosphorus toxicity, if anything but the slowest-release fertilisers are used. Any sort of root disturbance is also disastrous. Cluster roots are most common in the Proteaceae and are sometimes called proteoid roots, and they’ve also found in other families. But in the reserve, they’re also being found in families that have never been known for cluster roots elsewhere in the world.
I’d been invited out here by Hans Lambers of the Kwongan Foundation - Kwongan is the Noongar word for open country lacking timber-sized trees, and describes much of Australia’s SW. Hans and his students have studied the reserve and its botany extensively, and it’s from him I learned most of the above.
