Trees at Skyrail

Skyrail Nature Diary: April 2015

March started out quite dry and hot and sticky and thanks to Cyclone Nathan north of Cairns, we received a fair bit a rain for a few days. Now in April, it may very well rain given the fact that the wet season has had noticeably late starts over the last few years. Red Tulip Oak flowered in moderate numbers last month and should now be fully fruiting. The flowers are white and are borne in small clumps on top of the tree. The fruits are large samaras consisting of a spiny seed attached to a large papery wing. The fruits tend to stay on the tree for a while. The leaves are trifoliate, consisting of three leaflets covered in silvery brown hairs on the undersides. Red Tulip Oak grows up to 35 metres and is often buttressed. Timber of this species has high electrical insulating properties and was formerly used in northern Queensland as flooring. It is hard wearing and when sanded it takes a high polish. These trees produce a useful general purpose timber suitable for house construction where not exposed to the weather. 

Black Wattle flowered extensively along the Kuranda section of Skyrail. The small spikes covered in dull yellow flowers with no petals are quite striking. The fruits are twisted woody pods with dark curly stripes on a light background. Ants disperse the seeds in return for the stringy fruit flesh. The mimosa like leaves are shed permanently at a fairly young age and replaced by flattened twigs known as phyllodes. Black Wattle is a fast growing species and is typical of regrowth areas. Like most wattles, Black Wattle is often plagued by borers. Snapped branches of these trees are a very common sight. Although this is a fast-growing species, it can produce reasonable logs and the timber can be quite useful. 

Briar Silky Oak flowered in moderate numbers last month and with some luck, there should be some fruits on them now. The white flowers are borne on medium sized spikes or racemes. The fruits are orange woody follicles filled to the brim with papery seeds that are dispersed by the wind. The leaves start out with huge lobes and shiny brown hairs on the undersides. The texture is slightly papery. As the trees mature, they lose the lobes on the leaves and they turn yellow green. New growth is rusty red and hairy. These trees grow up to 30 metres and are often buttressed. The timber has a distinct oak grain to it and is ideal for doors thanks to its high density.

The Umbrella Tree is fruiting along both lines this month. The fruits are borne on giant spikes arranged in a whorl on top of the tree. Each separate fruit looks like a large hard inedible raspberry. These fruits are preceded by pinkish flowers that produce a large quantity of nectar that is often allowed to ferment. Umbrella Trees have an unusual life cycle. The fruits are eaten by frugivorous birds and dispersed. Depending on where the seeds land, one of three things can happen. If a seed lands in a Basket Fern it will germinate in the compost and live as an epiphyte for a few years. Over time, the Umbrella Tree sends down roots to the ground and becomes what is called a hemi-epiphyte. If the seed lands on granite ground, the seed will germinate and grow as a lithophyte, its roots invading cracks and crevasses in its search for water and scarce minerals. These plants rarely grow very large. If the seed lands on moderately good soil it germinates and grows into a clumping tree. The trunks are normally quite narrow and soft. The leaves are compound and consist of a very large pedicel topped by a whorl of large leaflets. The leaves leave triangular scars on the trunk when they are shed.

by Tore Lien Linde