Late spring along Florida’s east coast is a time when the dune sea oats are at their finest. Walking on the beach early Friday morning, my eye was drawn again and again to the clusters of these plants which serve as a barrier between beach and land. All of us living on this barrier island would call it a blessing if the oats grew in an uninterrupted line both north and south, but in an area where tourism plays a part, such growth would be rare indeed. The plants during May are colored new green by fresh spurts of growth and a burgeoning of yellowish seed heads that will take on a brownish hue in the heat of summer.
The sea oat (Uniola paniculata) is a semitropical perennial that dominates beach and dune communities along the east coast and the Gulf Coast of the US, Mexico, and on islands in the Caribbean. It is a tall, erect grass reaching six feet, with thin leaves tapering to pointed tips and growing to a length of 15-20 inches, approximately a quarter inch in width. The high reaching stalks produce large seed heads that flower in early summer. Sea oats function as a trap to catch wind-blown sand that falls and eventually becomes a mound initiating the formation of sand dunes. It is an excellent pioneering species, colonizing previously uncolonized areas and in most cases leading to the desired ecological distribution. Sea oats have a high tolerance to sea water and salt spray, as well as a high tolerance for drought. It’s active growth period is spring and summer and though the growth rate is slow the plant has a long lifespan.
Well suited to a saline environment, sea oats play an important part in barrier island ecology. Often used in soil stabilization projects, their long root structure forms dense surface roots and deeply penetrating roots that hold loose sand or soil together. Because they stabilize dune ridges, they are a crucial component of an area’s hurricane defense strategy and for that reason are a protected grass in most states along the east coast. Picking or disturbing sea oats is punishable by fine in Georgia, Florida, and North Carolina. On many Florida beaches signs posted at regular intervals advising beachgoers to stay off the dunes.
In addition to sea oats, a variety of grasses and wild flowers colonize a dune as it grows taller and create a protected environment on the landward side allowing for the growth of other plants, which in turn support birds and animals. At different times it is possible to see beach mice, doves and tortoises in sand dunes. Recently, ornithologists in Florida discovered that the pygmy burrowing owl makes its nest within sea oat colonies to conceal its young from natural predators. Without the sea oats and other plant life dunes would have no anchor and blow away, changing the ecosystem drastically and also making the coastline more vulnerable to hurricanes.