Out of Season Flowering and Fruiting

Skyrail Nature Diary: June 2012

May has been an unusually wet month for Cairns this year which has resulted in some trees flowering a little "out of season". The most obvious are the beautiful Alexandra Palms which have been covered in flowers on both sides of Red Peak station alongside creeks in the rainforest. The flowers are tiny and white with no petals, borne on bush-like structures known as 'panicles'. The fruits are small red drupes and are an important food source for a number of birds. The fronds have a slight silvery tinge to them, making them quite attractive, especially when seen from above. 

The Dodder Laurel started flowering late last month and should be fruiting shortly. The flowers are tiny and yellow, typically invisible like the flowers of most laurels whilst the fruits are small green berries. The Dodder Laurel is an unusual parasite. It starts life like an ordinary vine on the forest floor and makes its way to the canopy by winding around the future host’s tree trunk. Once it reaches the top, it attaches itself to a branch and taps into the host’s sap, sheds all of its leaves and severs its root.

Hickory Ash (Flindersia ifflaiana: Rutaceae) is currently fruiting along the entire cableway. The fruits look like small gherkins covered in tiny pyramids. They start out green and turn brown when ripe and split open into five fingers, releasing numerous papery seeds into the wind. The flowers are small and white and are borne on round clusters on top of the canopy. Despite being related to citrus trees, the flowers have no obvious fragrance. The leaves are compound (several leaflets combining into one leaf). The bark is thick and deeply fissured on mature trees. The timber is yellow and smells of curry - it is a multi-purpose timber.

Briar Silky Oak has been fruiting since April, some trees are even still flowering. The flowers are borne on upright racemes on top of the tree and are normally white. However, in Barron Gorge they are usually brownish in colour. The fruits are grey woody pods filled with papery seeds - interestingly these pods are red brown when unripe rather than green. The leaves are simple and strongly lobed when young with shiny brown hairs on the underside. Like most silky oaks, these trees have special cluster roots adapted to poor soils. The roots form clusters of closely spaced short lateral rootlets that make up two to five centimetre thick mats just beneath the leaf litter. They enhance nutrient uptake, possibly by chemically changing the soil environment to improve nutrient solubility. This is particularly useful in phosphorous deficient soils of Australia. Good soils actually cause the life span of silky oaks to shorten drastically.

Red Tulip Oak flowered unusually well along the cableway in April and it's quite likely that they will start fruiting in June. The flowers are tiny and white, borne on bushy stalks. The fruits are large round seeds with a half propeller attached which causes the fruits to spin in the wind, hopefully away from the mother tree. The leaves are trifoliate (each leaf consists of three leaflets) and are covered in shiny brown hairs on the undersides. The timber is dark red and has high electrical insulating properties. It was commonly used for flooring and when sanded it takes a high polish and is very decorative.

By Tore Lien Linde