Words and photos: Natarsha McPherson
Your Adelaide Park Lands are home to many kinds of plants, but it’s not always easy to identify them. Continuing this series, Know Your Park Lands Plants, we take a closer look at the plants that call your Park Lands home.
Walking along the River Torrens/Karrawirra Pari, you may have noticed tall grassy reeds clustered along its banks.
Found along rivers, lakes, and other wetland habitats, this aquatic plant is the Common Reed (Phragmites australis), a native species that you can find in every continent except Antarctica.
You will often find the Common Reed growing in dense reed beds with its roots submerged underwater. This cluster was found along the River Torrens in Red Gum Park / Karrawirra (Park 12).
Throughout your Open Green Public Adelaide Park Lands, the Common Reed borders the waterways. However, you may have previously confused their messy and dense appearance for a weed.
Growing up to 4 metres in height, their blue-green leaves are generally flat, narrow, and long; measuring up to 80cm in length.
With thick stems, the plant flowers during spring (September-November) wherein the shape and colour of its flowers bear a close resemblance to a close relative, wheat.
Residing predominantly within freshwater environments, the species uses the wind to disperse their seeds – covering large distances in high loads that allow them to grow quickly in dense units.
However, the species can also spread along banks through “horizontal runners” – stems that grow along the banks, establishing new roots and plant growth.
Flowers of the Common Reed appear fibrous with its colour ranging from light yellow to dark purple. This inflorescence was found along the River Torrens in Tarntanya Wama (Park 26)
Leaves and tall appearance of the Common Reed is supported by thick stems and dense reed beds. This group can be found in Tarntanya Wama (Park 26).
While temperate and humid regions have often reported the species as a weed, South Australian distributions are less expansive.
And though you might even overlook them for the beauty of your Park Land’s terrestrial plants, the Common Reed plays a critical role in protecting the River Torrens and surrounding Park Lands.
Structurally, these plants supply a buffer against erosion – slowing fast flowing waterways that form from land clearing for urban areas.
The Common Reed relies on constant inundation which makes them vulnerable to bursts of drought common across the state. This dense grouping can be found at the footbridge in Red Gum Park / Karrawirra (Park 12).
Subsequently, their extensive root systems also act as a filter to improve water quality by removing excess nutrients and pollutants from nearby run-off.
But, more importantly, these reeds provide critical shelter and food for a variety of animals, including small fish, insects, and birds that you may find along the bordering parks.
Bridging the gap between aquatic and terrestrial landscapes with thick soil beds – many birds use the Common Reed as nesting or foraging sites.
As the River Torrens and your Park Lands face ongoing threats from development, invasive species, and drought conditions, the presence of native species such as the Common Reed is one of our best natural strategies for protecting habitats and biodiversity!
Don’t be confused!
Photos: Oliver C. Stringham; Insiderelic (from iNaturalist)
The native Common Reed (left image) can easily be mistaken for the Giant Reed (Arundo donax), an invasive weed (right image).
To differentiate them, note that the invasive species has a much thicker, woody stem with wider leaves and larger stature – growing up to around 10 metres in height.
Want to know more about the plants in your Park Lands?
Head over to iNaturalist, where you can record, share, and discuss your findings with fellow naturalists.
See the other plants featured in this series here:
https://www.adelaide-parklands.asn.au/know-your-park-lands-plants
