Spartina alternifolia (Poaceae)
Origin: Eastern shoreline of North America
Back in 1997, the Marie Selby Botanical Gardens undertook a massive shoreline restoration project in front of the Christy Payne Mansion. When we acquired the Payne property, then owned by Patricia and James Paulk, there was sod grass lawn and ornamental palms growing all the way to the tidal zone. In an effort to filter runoff into Sarasota Bay from not only our Gardens, but downtown Sarasota and U.S. 41 as well, we created a tidal lagoon in the middle of the lawn, removed all of the invasive and ornamental plantings, and replaced them with Florida coastal natives. A shell mound was created, complete with a small wild banyan (Ficus citrifolia) which is huge today, as well as a trail to the new beach.
If filtering runoff was the benevolent reason behind the shoreline restoration project, preventing erosion was also an obvious concern for Selby Gardens. Coastal property owners are constantly fighting with the tides, waves, and storm surges to keep their land from turning into sea. We didn’t want to build new sea walls, which are detrimental to the ecology of the bay, and also wanted to educate the public on ways to combat shoreline erosion naturally. So dozens of red mangroves were planted, along with hundreds of Spartina alterniflora. Both of these species of plants act not only as shoreline stabilizers, keeping sand and silt in place with their root systems, but can also help to add land mass to the shoreline, especially the Spartina. It grows along the edge of the shore, and as it ages it traps and collects sediment and small marine animals such as mussels and oysters. This, in turn, “grows” the shoreline, at which point the Spartina grows even further out into the water, catching and trapping even more sediment and animals, and the process continues.
Saltmarsh cordgrass develops a hollow rhizome which is buried in the sediment of the salt marsh. The grass grows in excess of a meter tall, and is an ideal choice for shoreline restoration projects, quickly forming a dense bed which not only helps provide erosion relief but also provides habitat for crustaceans, mollusks, and nursery fish. It grows so effectively, in fact, that it has proved itself to be a major invasive species in other parts of the world, not only growing where it doesn’t belong, but also breeding with native Spartina species to create nuisance hybrids.
You can see our saltmarsh cordgrass beds, now almost twenty years old and doing great, along the northern shore of the Gardens. The best view is from the beach on the backside of the tidal lagoon. The plants are currently blooming; specimens were just collected for our herbarium.
Text by David Troxell