Wednesday, May 6, 2015

The Streblus Mystery

Whalebone tree, Streblus pendulinus (Streblus brunonianus)

Why do some of our local Streblus seedlings have mature-shaped leaves from birth, while others have odd elongated leaves with lobes?
This seedling at the Bunya Mountains shows the whole range, from long thin baby leaves to the adult-shape leaves at the top.

Here is a closer look at the leaves. I didn't put them in order of age. Leaves like the narrow one at the bottom of the photo were produced first. The leaf second from the top is the mature leaf shape.

So far as I can discover, the reason for the difference is not known. I have wondered whether it indicates whether the seedling is a male or female tree, but have never found anyone who has tracked a seedling’s life from juvenile leaves to flowers to find out.

The male flowers (above) are very obviously different from the tiny green female flowers.

Female trees have these little yellow fruits, which are attractive to birds, including chooks.

In the Streblus fruiting season, these chooks run to my friends’ female whalebone tree, as soon as they are let out of their yard each day. They scratch in the litter for newly-fallen fruit, and will jump up to get them off the tree.

Like so many trees of our drier rainforests, whalebones can be tall trees with no low branches, when they grow in forests. They can also thrive in dry, hard country, changing their shape to suit their conditions.

The paddock this tree grows in has probably been supporting cattle for at least a century. The tree hadn’t even managed to form its typical single trunk before the cows started “pruning” it, but it has struggled on to produce this wonderful bird-sheltering plant, with tight growth of branches and leaves.

For more on whalebone trees, see my blog of February 16, 2008,
or type Streblus into the white search box at top left.

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