Imagine walking through your local bushland reserve and every time you did so the types of plants you observed had dramatically changed.  This is what it can be like when you visit a wetland and try to identify the plants in different seasons or over different years. Depending on the ecological drivers of the wetland, particularly the hydrology, different plant species will emerge when their unique set of conditions are right.  The depth, season and duration of wetting and drying provide a constantly changing environment for wetland plants.  Figure one illustrates changes in wetland plant species composition during wet and dry phases at Scotties Billabong in far north west Victoria.

Figure 1: Scotties Billabong in wet phase

Figure 1: Scotties Billabong in wet phase

Scotties Billabong in dry phase

Scotties Billabong in dry phase

Figure 1: When inundated Scotties Billabong supports a vegetation type known as Aquatic Herbland, which is composed of species including Billabong Pondweed, Wavy Marshwort, Pacific Azolla and Eel Grass (left). When the billabong dries out it supports a vegetation type known as Floodway Pond Herbland, which is made up of species including Southern Liquorice, Old Man Weed, Sprawling Saltbush, Hairy Carpetweed and Mousetail

Wetland plants have evolved unique and frequently amazing survival strategies to cope with and benefit from these constantly changing conditions. Images below illustrate some examples of these adaptations.

Water Ribbons (left) have tubers that store carbohydrates which can be drawn upon to survive prolonged dry periods. These stored carbohydrates are also edible by humans, making Water Ribbons an important bush tucker species.

Wavy Marshwort (centre) has floating leaves allowing it to move with rising and falling water levels.

Submerged aquatic species such as the Eel Grass (right) can extract the carbon required for photosynthesis from carbonates dissolved in water, as only limited amounts of carbon dioxide may be available under water. The pollination strategy of this submerged species is quite remarkable. The male flowers of this species are free-floating, while female flowers are attached to the base of the plant on a coiled stem (pedicle). The male flowers are released to float on the water surface, where they come into contact with the female flowers that rise to the water surface when ready to be pollenated. When they have received pollen from a floating male flower the stem of the female flower re-coils, drawing the fertilized ovaries back down to the of the base of the plant where the seeds can mature in relative safety.

 

The ability to accurately identify wetland plants in these ever-changing environments is a very important skill for wetland managers. Ecologists Damien Cook and Elaine Bayes will run a three-day Wetland Plant Identification Course, commencing in October 2017.  The course will run over a 6-month period from spring to autumn. Each day will focus on a different wetland habitat (water’s edge, deep marsh and mudflat) and be timed so as to follow the wetting and drying of the stunning Reedy Lagoon at Gunbower Island and nearby wetlands.

The spring session focuses on grasses, sedges and rushes, the summer session on submerged and floating aquatic plant species and the autumn session on plants that germinate and grow on drying mud.  Each session includes a field trip to look at plants in their natural habitat and to collect plant specimens, presentations on plant ecology and key identification features and time for keying out plants in small groups. For more information, call Elaine on 0431959085 or check out the website http://rakali.com.au/education-and-training.