The dynamic upper intertidal zone between mean and high tides is home to a number of specially adapted salt marsh plants. Plants that grow in estuaries adapt to tolerate regular flooding and inundation by salt water. At the same time, these plants play an important role in stabilizing estuary soils. In addition, the salt marshes help with flood mitigation, habitat and food sources for wildlife, and carbon sequestration. However, climate change and rising ocean levels can threaten the health of the salt marsh and the plants that grow there.
The Chemainus River estuary is an expansive salt marsh that is easily accessible by a farm road/walking trail. At low tide, botanists can explore areas of the salt marsh that flood at high tide. The extensive salt marsh is a maze of mud flats, areas stabilized by salt marsh plants, and constantly changing tidal channels, pools, and runnels. It’s a dynamic environment. As a result, exploring carefully and intentionally is important. Since the wetland is also home to countless mosquitos and other insects, moving slowly can sometimes be challenging!
Some Salt Marsh Plants
Because the Chemainus River estuary is so large, the plant communities are diverse and spread over a wide area. It is an advantage to wear rubber boots to navigate the wet and muddy landscape. Jumping over some narrow tidal channels, I ventured in the upper edges of the marsh to see what kinds of plants I could find. The bright orange of salt marsh dodder particularly caught my attention.
The plant community at the edge of the mudflats in the estuary has several distinctive members. Firstly, at the edge of the mud, patches of American glasswort (Salicornia pacifica) are common. Masses of wiry, parasitic salt marsh dodder (Cuscuta salina) cover parts of these glasswort areas. Secondly, salt-tolerant common orache (Atriplex patula) occupies slightly higher ground or mixes with the upper areas of glasswort. Then, clumps of Oregon gumweed (Grindelia stricta) mark another slightly higher elevation. Finally, in a more sheltered part of the marsh, seaside arrow-grass (Triglochin maritima) was common among grasses and sedges. Detailed descriptions of all of these fascinating salt marsh plants follow below.
Salt Marsh Dodder (Cuscuta salina)
Salt Marsh Dodder (Cuscuta salina) is very visible in the Chemainus River estuary. The bright orange, threadlike plant occurs in the upper tide line areas along the edge of the tidal marsh. Large tangles of it intertwine with the salt marsh plants which it is parasitic on. At a distance, the dodder looks like discarded orange fishing line washed in by the tide.
Salt marsh dodder is a holoparasitic plant found in tidal salt marshes. It winds its way around the stems of salt marsh plants and is particularly common on American glasswort. Lacking leaves, it uses suckers to penetrate the plant tissue of the host plant. Because it is unable to photosynthesize, the host plant provides salt marsh dodder with the nutrients it needs to survive. Eventually, small white flowers appear. These flowers produce large quantities of seed. Finally, when the seeds drop to the soil, the cycle begins again.
Salt marsh dodder has adapted to a saline environment and periodic tidal flooding. Despite its parasitic nature, the plant plays in an interesting role in the salt marsh ecosystem. The flowers provide a source of nectar for small insects. In addition, dodder helps to stabilize the dynamic estuary ecosystem. In fact, the “netting” formed by the threads of dodder helps to provide some resistance to erosion, holding plant communities together.
American glasswort (Salicornia pacifica)
One of the more common salt marsh plants in the tidal flats is American glasswort (Salicornia pacifica). Glasswort is a fleshy, jointed, essentially leafless (very small, scale-like leaves are present) plant that forms large mats in the salt marsh. Because this succulent plant is edible raw or cooked, it is also called “sea asparagus” and “pickleweed.” Picked and eaten in the marsh, it often has a salty taste due to exposure to salt water at high tide. Surprisingly, the common name “glasswort” comes from the traditional practice of burning the plant to make the alkali needed for making glass. American glasswort typically occupies a band between exposed mudflats and upper areas just beyond the high tide range.
Similarly to other salt marsh plants, American glasswort has special adaptations to deal with exposure to salt water. The plant’s primary source of water is tidal. As a result, glasswort takes in salt water, processes the salt out of the water and stores the excess brine in vacuoles in terminal segments of the plant stems. When these segments become full of brine they turn red and drop off which removes the salt. It’s a fascinating adaptation to living in a harsh environment!
Common Orache (Atriplex patula)
Another common salt marsh plant found in the Chemainus River tidal wetlands is common orache (Atriplex patula). This plant grows in the same zone as American glasswort and often intermixes with it. Common orache is a distinctive looking plant and has a number of features that make it easy to identify. The fleshy, almost succulent, leaves are lance-shaped to oblong with an overall triangular shape. In addition, a fine pattern of raised white spots covers the leaves and stems. Similar to pickleweed, orache is also edible (in small amounts due to the accumulation of oxalate salts). Steamed, it apparently is similar in taste and texture as spinach. As with all native plant harvesting, moderation and awareness of potential hazards should be considered before proceeding.
Common orache is a hardy halophyte that does well in waste areas and saline environments like tidal salt marshes. It is well adapted to poor soil conditions and withstands periods of drought and submergence in salt water. In addition, the deep roots of the plant help to stabilize the estuary mudflats, working with American glasswort and Oregon gumweed to reduce the erosion in coastal landscapes.
Oregon Gumweed (Grindelia stricta)
Oregon Gumweed (Grindelia stricta) is common in the upper parts of the salt marsh. The bright yellow flowers make it easy to find. Usually, it is associated with upper beaches, rocky shores and estuary wetlands.
Also known as entire-leaved gumweed, this plant has a number of distinctive features which help identify it. The flower consists of a flat topped disk with numerous petals. Sticky green bracts that give the plant its common name surround the yellow flowers. Often a white resin covers this part of the plant, giving it a latex-like appearance. The stems and leaves have sticky glandular hairs as well.
Entire gumweed blooms in June and July, making it an important source of late-season pollen and nectar for insects like butterflies and bees. In a dynamic estuarial environment, Oregon gumweed plays an important role in stabilizing soil and preventing erosion.
Seaside Arrow-grass (Triglochin maritima)
Another interesting salt marsh plant can be found in the sloughs at the Chemainus River estuary. Seaside arrow-grass (Triglochin maritima) grows in the protected brackish meadow behind the dyke and between the outer rocky ridge and the higher stretch of inner land. There are some deep tidal trenches in this part of the estuary, but the saline marsh is dominated by grasses and sedges. Seaside arrow-grass grows here in a a small, well defined patch on the edge of the wetland.
Identifying this distinctive salt marsh plant is fairly straightforward. Seaside arrow-grass has basal leaves that form a cluster of tall, upright leaves. The leaves are fleshy, long, linear, and somewhat flattened. The flower spikes are dramatic, spike-like clusters rising above the leaves. The flowers are numerous, small, inconspicuous and greenish in colour. The dense root mat of seaside arrow-grass produces a ring of elevated soil that other wetland plants can colonize.
Finding Salt Marsh Plants at the Chemainus River Estuary
Exploring the salt marsh at the Chemainus River estuary is best at a low tide. Make sure to check the local tides and take care not to get trapped out on tidal flats. Waterproof shoes or rubber boots are recommended, but not essential. It is possible to avoid areas of deep mud and standing water and still see all of these salt marsh plants. Move slowly and intentionally to minimize your impact in the salt marsh.
All of the plants described above were photographed on the south side of the Chemainus River estuary. This part of the estuary is easily accessible via public access farm roads. Expect about 4.5 km of walking (out and back) in exposed sun to get to the part of the estuary where these plants grow. Mosquitoes are common.
Getting There
From Chemainus, follow Chemainus Road towards Crofton. After crossing the Chemainus River look for Swallowfield Road. Turn left on Swallowfield Road and drive to the parking area at the end of the road. The Chemainus River Estuary Trail begins by following the farm access road on the other side of the gate in the parking area.
From Duncan, follow Highway 1 towards Chemainus/Ladysmith. Watch for the Chemainus Road/Crofton exit and turn right to leave Highway 1. Follow Chemainus Road until you see Swallowfield Road. Turn right onto Swallowfield Road and drive to the parking area at the end of the road.
