By Dale K. Nichols (Board Member)
Dear friends of Shirley Heinze Land Trust: This is the fourth in a series of “snapshots” featuring our Beverly Shores/Great Marsh preserve. My last post included a high-level overview of the different families of plants that grow here. This one will delve into more detail on one of them—the Sedge family.
What is a Sedge? Sedges (Cyperaceae) are members of a large family of plants that, like Grasses (Poaceae), Cattails (Typhaceae) and Rushes (Juncaceae), are commonly found in wetland habitats such as marshes, swamps, bogs, and that have adapted to thrive in moist to waterlogged conditions. Sedges are characterized by their leaves (which are long, slender, and grass-like with parallel veins, and often arranged in three vertical rows along the stem, giving them a distinctive triangular shape in cross-section); stems (which are typically cylindrical or triangular in shape, providing structural support for the plant); flower structure or “inflorescence” (which may be organized as spikes, umbels, panicle or head-like clusters, with individual flowers often small and inconspicuous in appearance); and fruit structure (called archenes, which are typically small, contain a single seed, and are either scale-covered or, in the case of Carex species, are contained within small sac-like structures called perigynia).
Why are Sedges Important? Sedges play an essential role in the health of the Great Marsh and other wetland habitats. Here are a few of their notable ecological characteristics and values:
- Wetland Stabilization: Sedges, with their extensive root systems, play a significant role in stabilizing wetland soils. Their dense network of roots helps prevent soil erosion and provides structural stability to marshes and wetland areas.
- Water Filtration: Sedges are known for their ability to filter and purify water. Their dense root systems help to trap and retain sediment, nutrients, and pollutants, thus improving water quality by reducing sedimentation and filtering our contaminants.
- Habitat and Food Source: The dense vegetation and seed heads of Sedges offer cover and nesting sites for birds, mammals, and amphibians. Additionally, the seeds, shoots, and rhizomes of Sedges serve as a food source for numerous wetland-associated animals.
- Wetland Hydrology: Sedges play a role in regulating water levels within wetland ecosystems. They can tolerate periods of flooding and high-water tables while also assisting in water retention during drier periods. By influencing hydrological patterns, Sedges help maintain suitable conditions for wetland plants and animals.
- Carbon Sequestration: Wetlands, including those dominated by Sedges, are efficient at sequestering carbon. The organic matter accumulated in Sedges and other wetland plants gets stored in wetland soils, helping to mitigate climate change by reducing carbon dioxide in the atmosphere.
What types of Sedges can be found in our Great Marsh preserve? Twenty-four different Sedge species have been identified as growing in our Great Marsh preserve, comprising close to 10% of its total plant diversity. These species are members of a number of different genuses within the broader Cyperaceae family. The three most represented genuses in the Great Marsh are:
- Carex (commonly known as “true sedges”) – 15 species;
- Cyperus (commonly known as “flatsedges” or “nutsedges”) – 6 species; and
- Scirpus (commonly known as “bulrushes”) – 3 species.
How can you tell plants in the three genuses apart? Members of the SHLT stewardship staff could lecture for hours on the differences between genuses and individual species, but for a lay person like me, one way to distinguish plants in the three genuses is by their flowers. The flowers of all three genuses are “inconspicuous” (that is, not showy) and form in clusters called inflorescences that are arranged in spikelets. The spikelets of the Scirpus genus are generally larger and more open than those of the Carex, while those of plants in the Cyperus genus are typically arranged in compact or umbrella-like clusters called umbrels. Here are photos of a number of representative species.
Which species of Sedge does SHLT collect as part of its Great Marsh stewardship efforts? Stewardship staff and volunteers have been actively collecting and replanting seeds from many different plants over the past several years to encourage their more uniform presence across the entirety of our Great Marsh preserve. Among the Sedges, we have concentrated on Carex species (all we can find), and on seeds from the Dark green bulrush in the Scirpus genus.
When are the seeds ready to collect? While harvest times for individual species can vary widely from year to year, depending on the weather, there is a pretty predictable pattern as to which Sedge seeds ripen first, later and last.
The earliest of the Sedges is usually the Fox Sedge (Carex stipata). This season it was ready to harvest in mid-June. We had a truly remarkable crop, especially in the block between McAllister and Wells. I was able to participate in one of two workdays devoted to collecting it. Between the efforts of Stewardship Ecologist Doug Botka, our new Volunteer Coordinator, Jim Haniford, and volunteers, we collected 38 oz of Fox Sedge seed on that day. That translates into about $1,140 worth of effort using the current $30/oz market price for this seed if purchased commercially.
Next up, probably in late July, will be a variety of other Sedges, including:
- Bottlebrush sedge (Carex lurida);
- Bristly sedge (Carex comosa);
- Broom oval sedge (Carex scoparia); and
- Crested sedge (Carex cristatella).
Then, in the August to September timeframe, we can expect to harvest the last of the season’s Sedges, including:
- Hop sedge (Carex lupulina); and
- Dark green bulrush (Scirpus atrovirens).
SHLT relies heavily on volunteers to assist in our seed collection efforts. If you would like to help, all volunteer workdays are posted in advance on the Shirley Heinze website (www.heinzetrust.org) and through email blasts. You can sign up online or contact Volunteer Coordinator Jim Haniford directly at jhaniford@heinzetrust.org.
Shirley Heinze volunteer workdays are fun, educational and a great way to meet other nature-lovers. Please come out and join us!