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15 Jul 2020

Wattles – arising from the ashes of a Black Summer!

Everyone’s talking about economic recovery, but what’s happening with the recovery of our native flora after years of drought and intense bushfires? Fortunately, after the Black Summer (we’ll never forget) the burnt bush is already responding to the late summer and winter rain.

New (epicormic) growth emerging from the trunk of Eucalypts, as bushland near Oakdale starts to recover after the intense Green Wattle Creek fire in December 2019.


During summer, the massive Green Wattle Creek fire at Oakdale in SW Sydney featured on national and international news. These were full ‘crown fires’ consuming all vegetation from tree crowns to ground leaf litter. A recent visit to one of these high fire impact sites revealed the amazing resilience of our native flora, with many plants already germinating and growing strongly.

 
Wattles (Acacias) were leading the charge in this post-fire germination frenzy - from seed stored in the soil. Wattles are the great Aussie survivors and produce large quantities of hard black seeds, which the ants often carry off and bury. The heat of bushfires cracks the hard seed coat and promotes germination and the next generation starts.
 
It might seem like a ‘live fast die young’ approach to life, but wattles have evolved over millions of years to deal with fire, and seeds can live in the soil for decades. But the wattle story isn’t finished there – as some of the important first colonisers after a fire, they are soil improvers able to use special root nodules to extract nitrogen from the air and return it to the soil.  


With their hard, shiny seed coats, it’s not surprising that wattles are some of the longest-lived seeds in the PlantBank seed collection. We expect wattle seeds, which are stored in foil packets at -20°C, to last more than 200 years. So, when you’re enjoying the amazing golden yellow wattle flowers at the Australian Botanic Garden Mount Annan this winter, give a thought for these Aussie survivors and how they’re an important natural part of our bushfire recovery.

Discover more and go behind-the-scenes in our podcast 

In this episode of Branch Out, go deep into the Australian PlantBank labs to discover how scientists are collecting seeds, using x-rays, tissue culture and cryopreservation to protect plants from extinction.

Category: Education
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