Angair walks are not always lengthy, the walk this month was no more than 500m, but several hours were needed to examine the diverse range of plants thriving in this challenging environment.
As we enjoyed the view of the estuary the importance of estuarine plants growing along the creek edge was discussed; provision of habitat was an obvious choice after Ellinor described the many bird species found in the estuary. Swamp Antechinus and Swamp Rats were also mentioned as well as the presence of many invertebrates.
On examining the spreading nature of the estuarine plant roots, we discovered they worked collectively, creating a mat which holds the soil tightly, reducing the risk of erosion and soil loss.
Looking across the swathe of Sea Rush, Juncus krausii subsp. australiensis
Saline soils are associated with river and creek estuaries, the salt in the soil creating toxicity problems for plants not adapted for survival in this environment. As we closely examined the estuarine plants, we discussed their different adaptations that ensure survival.
Survival in a saline environment
Salt glands are commonly found on many estuarine plant leaves, the glands excrete accumulating salt, it then washes back into the soil and the cycle starts again.
Through the use of magnifying-glasses we were able to see salt glands on the leaf surfaces of the weed Orache, Atriplex prostrata.
The magnification was not strong enough to see the salt glands on the leaves of Australian Salt-grass, Distichlis distichophylla, but we did appreciate the distinctly flat nature of the leaves which form two rows on opposite sides of the stem. This is known as a distichous leaf arrangement.
Australian Salt-grass
Beaded Glasswort, Salicornia quinqueflora subsp. quinqueflora is one of the worlds most salt tolerant plants, and most importantly provides an essential food source (seed) for the Critically Endangered Orange-bellied Parrot.
The leafless Beaded Glasswort has thickened spongy stems which store water which assist in diluting the salt within the plant cells. Their roots can also compartmentalise salt before excreting it into the soil.
Beaded Glasswort
What looked to be a monoculture of Sea Rush offered so much more. We also discovered Streaked Arrowgrass, Triglochin striata, Creeping Brookweed, Samolus repens, Jointed Hemichroa, Hemichroa pentandra, Shiny Swamp-mat, Goodenia radicans and Creeping Monkey-flower, Thyridia repens, closely growing together, forming an estuarine habitat.
Close inspection of Creeping Brookweed
Creeping Brookweed
Jointed Hemichroa
Creeping Monkey-flower
Gail Slykhuis
Photos by John Lenagan and Gail Slykhuis