Guioa semiglauca (F.Muell.) Radlk.
Australian Crow Ash
Christine Ashe
Don Herbison-Evans

This is a medium sized rainforest tree, round about 18m, but can grow taller in very good conditions, with a spotted smooth grey trunk. It has rather dull, dark green, thick leathery leaves, which are blueish grey underneath, hence the name semi-glauca.

Underside of leaves

The leaves are pinnate-compound with 2 to 6 pairs of leaflets, each 4 to 8cm long, with one single leaflet at the end of the stem. The leaves are quite heavily veined, ovate to elliptical, with a soft blunt tip at the apex in adult trees.

Older leaves

Guioa semiglauca is still fairly common in protected coastal areas in rainforests along the east coast of Australia, from about Nowra to Mackay in North Queensland. It took me years to recognize this tree in my patch of rainforest because it blends into the background very well. I find it much easier to figure out what tree is if I have a flower or something I can use to track it down. With this tree it was just a nondescript rather dull tree for months on end. Now that I know it I can see that it is one of the backbone trees along the creek, which no doubt hold the creek banks together, provide habitat and shelter for bird and beast and also food at the appropriate time of the year.


There is nothing about the tree that makes it stand out until it flowers in early spring. It doesnít flower every year but when conditions suit. It can be covered in masses of small lightly perfumed flowers. This is not one of those fly-by-night trees that flaunt their blossom for a week or so. No, this tree begins slowly and builds to a crescendo of flowers as the weeks progress. The flowers are not particularly showy, being a greeny cream and very tiny, but in a good year, there are masses of them borne in dense clusters in the leaf axils. I admit this many are rather difficult to miss, but this year has been a particularly good one for many of the trees and so there was a mass bloom. Iíll be interested to see as the years pass just how often it flowers this prolifically.

In fact if you are not paying attention, even with lots of flowers, you may not notice the flowers at all as they blend in so well with their surroundings, but if you are bee or a butterfly or moth, you know they are there. Not only do they blend in well but they flower high in the canopy of the tree which is surrounded by other thick bush making them rather hard to see.

Before I had put a name to my trees I noticed one beginning to bud on the edge of the creek. I watched the buds develop and finally open and then noticed with great interest that thousands of bees visited and feasted on the nectar.

As successive trees opened their flowers, very high in the rainforest canopy, I could tell just by the drone of the bees, that something special was happening way up high, and then it took a pair of binoculars before I was sure.

butterfly meeting point

Even before the buds of the Guioa semiglauca were fully opened, it was attracting dozens, perhaps hundreds, of fluttering brown and orange tiny butterflies (Hypocista metirius) in early October. It was a definite meeting point.


Once the flowers finish the tree maintains interest for a little longer with the attractive seed capsules, 8 Ė 12 mm wide. These are flattened with 2 -3 wing like lobes which swell to contain brown seeds covered in an orange-red aril in summer.


Then it is the turn of the birds, who find the seeds very attractive. Those that are not recycled this way fall to the ground and generally germinate. These young trees are browsed by wallabies and so not many make adult trees.

The leaves are also eaten by caterpillars of species such as

Avatha discolor

Link to
Flowers in Australia

(updated 23 March 2008)