Plants are Amazing- Series Two

Well I hope you have all been admiring the many amazing adaptations that plants have developed to cope with the harsh Australian climate in your gardens or while bushwalking, and have possibly noticed a few more structural features that plants have and maybe questioned the reasons why they have these features. Detailed below are some more amazing features that you may have noticed along your tracks.

As you walk around the garden or along your bushwalks you will see numerous examples of leaf adaptations designed to cope with low rainfall, searing summer temperatures, or saline soils. Examples of leaf adaptations include short, leathery leaves which have reduced surface area to minimise evapotranspiration (water loss due to evaporation). Other examples are terete (tubular leaves), spiky or in rolled leaves. Look at the leaf structure of Spinifex plants. Wattles have phyllodes (modified stem structures) instead of true leaves- this is believed to be a response to our infertile soils, rather than to the dry, hot climatic conditions.

Some heat defecting modifications of leaves include the presence of stellate (star-shaped) or branched hairs, scaly or waxy cuticles (outer surface of leaves), and the blue-grey colouration of many plants. Many of the Emu Bushes have hairy stems or leaves, and many of them are also blue-grey coloured. Saltbushes are well represented in arid regions in Australia, and many of these have scaly or hairy foliage, as well as succulent leaves (water-storage), and vesicle structures on their leaves to assist with salt exclusion for survival in saline soils.

Another leaf modification some plants have to limit evapotranspiration is the placement of stomata (the structure where gas exchange occurs) - some plants limit these to the underside of leaves, while others have their stomata hidden in pit-like structures, often covered by fine hairs.


The orientation of leaves in plants is often with the leaf edge turned toward the sun in order to reduce the surface area impacted on by evaportranspiration. Look for this feature in some wattle species.

Stem modifications are also apparent in some plant species to help them survive the harsh climate. Mallees are multi-stemmed gum trees (Eucalyptus species) that have modified stem base called a lignotuber which allows the trees to sprout again after severe drought or fire has killed off the top growth. Multiple growth points under the bark of trunks of many Eucalypt species allow them to re-sprout along their trunks after fires.

Stay tuned over the next fortnight for more amazing plant adaptations.

Imaged sourced from Botanical Gardens at the University of California, Los Angeles (UCLA)