Plants

Gulf Islands National Seashore comprises about 95,000 acres of barrier islands, mainland areas, and adjacent submerged lands along the northern coast of the Gulf of Mexico. Throughout these holdings are areas apparently devoid of vegetation, but each area contains a surprising number of plant species.

Some plants are easily observed; others are sighted only by the keen-eyed naturalist. Most noticeable are the flowering plants with the conspicuous blossoms, like St. John's wort, standing cypress and woody goldenrod. Flowers of Florida rosemary and turtle grass may go unnoticed. Not all plants have flowers: pines produce seeds in a cone instead of a flower; mosses, ferns, fungi and algae reproduce by spores instead of seeds; lichens, a combination of a fungus and an alga living together, also reproduce by spores.

Habitats

Different plants are found in different habitats, as defined below. Each habitat is an area with a particular combination of environmental factors where certain plant and animal species live.

Gulf
Algae, including Sargassum, grow in the Gulf of Mexico, and sometimes wash ashore on Florida barrier island beaches.

Dune Strand (includes primary dunes)
Sand dunes up to 10-20 feet in height are parallel to the Gulf, and often continuous in appearance; areas adjacent to dunes are included. Gulf beaches are south of primary dunes, while the north face joins the dune-swale. (Bay and sound shorelines in some places provide a similar habitat.)

Dune-Swale
Isolated or connected dunes interspersed with low, wetland areas are called swales. Dunes are dry and sandy. Sometimes swales are flooded with fresh rain water; their soil remains moist even during dry periods. Tree species in the dune-swale are shrub-like.

Forest-Marsh
Taller pines and oaks, shrubs and other plants grow in dry sandy soils; marshes typically contain standing fresh water.

Interfaces, or transitions
Transitions between dry and wet soils of the dune-swale and forest-marsh support a mixed plant population.

Salt Marsh
Salt-tolerant wetland plants grow along sound and bay shores at some sites. Water is brackish, a combination of salt and fresh waters; its level fluctuates with the tides.

Sound or Bay
Water in bays and sounds is brackish. Aquatic grass beds grow where water is shallow enough for light penetration.

Mainland Forest
Naval Live Oaks area mainland forest is made of several distinctive plant associations. Live oaks draped with Spanish moss; southern magnolias; hickories; and eastern red cedars typify the live oak hammock community which is found along the coastal fringe. The sandhill community occurs on ancient sand dunes found in the center of the peninsula. Sand pine, longleaf pine, turkey oak, saw palmetto, prickly pear cactus, and yaupon holly are characteristic species of this unique forest type. The marsh community is a meeting place of land and water. Composed of tall grasses such as cordgrass, these wetland areas are among some of the richest habitats.

Environmental Indicators

Soil type and chemistry, light intensity, wind exposure, moisture and air quality are among the environmental factors that determine what kinds (Species) of plants live in certain areas. Exposure to salt spray permeates the presence of sea oats on dune strands, while it slows or prohibits the growth of other plants on the beach. Sea oats help form and stabilize dunes, which in turn block the salt spray and allow less salt-tolerant plants to grow in habitats behind the dunes. Presence or absence of plants in a given location indicates the surrounding environment.

We need your help

Knowledge and study of the park's plants help guide the National Park Service in protection and preservation. You can play a role in this endeavor, too, by respecting and caring for the resources around you. Please do not pick wildflowers.

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Last Updated: 1/6/03
Webmaster Gulf Islands
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