Trees in the Rainforest

Skyrail Nature Diary: August 2012

This month we will be looking at the various primitive trees that produce seeds without the use of flowers.

Queensland Kauri (Agathis robusta: Araucariaceae) is the most obvious tree at Red Peak station. It can grow up to 50 metres on decent soil, whilst 30 metres on the granite ground at Red Peak is probably the limit. The female cones look like a ball of thread and literally fall apart when ripe. The male cones look like brown fluffy index fingers. Both male and female cones are produced by the same tree but never at the same time. This avoids self pollination. The trunk is incredibly smooth. Even the normal presence of knots where a branch used to be is absent on these trees. Rainforest Treets All bark is shed regularly to maintain this smoothness. It is possible that this is a defense against cyclones, presenting the strong winds with very little to grab a hold of. The bark and sap are both acidic which may explain why termites and insect borers avoid it. These trees were second only to the Red Cedar (Toona ciliaris: Meliaceae) as the most sought after timber in the Wet Tropics. The beautiful honey golden timber was used in the production of ships masts, cabinet furniture, walls and floorboards. These Kauris resemble the famous ones in New Zealand but have two significant differences. Firstly, the New Zealand Kauri (Agathis australis: Araucariaceae) is a swamp dweller and likes wet feet. The pines in Australia prefer areas with good run-off. Secondly, the New Zealand Kauri has a massive girth due to the almost temperate conditions where it grows. Ours are tall and skinny due to the enormous competition for space in the tropical rainforest.

Weeping Brown Pine (Podocarpus grayae: Podocarpaceae) grows up to 30 metres and has fleshy female cones. The cone itself is a dark red berry with a grey/green seed hanging underneath. The flesh is edible while the seed is toxic. The male cones are tiny yellow fingers that occur in clusters of up to four cones. Male and female cones usually occur at different times to each other on any particular tree. The leaves are long fleshy straps that droop noticeably. When new, the leaves are a striking yellow. These trees make nice pot plants for indoors when young and produce a very useful timber to make boxes, butter churns, office fittings, kitchen fittings and internal house sheeting.

Cypress Pine (Callitris macleayana: Cupressaceae) is a beautiful tree related to the junipers and other true cypresses. These timbesr are often very hard and resistant to termite attack. The leaves are tiny scales tightly compressed on the surface of the twigs. The female cones look like brown woody pyramids that split into six valves when ripe. The tiny seeds have papery wings that allow them to float down to the ground like helicopters. The male cones are tiny yellowish spikes often occurring in clusters. These trees normally prefer drier areas. Callitris intratropica is a close relative found out west near Undara and have small woody globe shaped cones that were used for Christmas decorations.