Trees of the Lower Suwannee Region: A Natural History

Part IV. Cabbage Palm – A Survivor

Cabbage palm (Sabal palmetto), a tough generalist, is nearly ubiquitous in the region, including both the Lower Suwannee and Cedar Keys National Wildlife Refuges. Swamps, offshore islands, old sand dunes, river bottoms, and a variety of upland habitats support these trees. Their almost ubiquitous presence in a variety of situations seems so natural that in most landscapes they are so familiar as to often escape notice. A single factor accounts for the wide range of conditions in which cabbage palms are found, and it is their toughness—their wide range of tolerances for adverse conditions.

Distribution of Cabbage Palm. Largely restricted to the Florida peninsula, cabbage palms occur along narrow coastal bands northward to South Carolina and extreme southeastern North Carolina, and westward along the Gulf of Mexico through the eastern Florida panhandle. They are the only tree-like palms to naturally extend this far north in North America. Planted cabbage palms can occur in a much wider range, as do some other palms not native to North America.  

Cabbage palms are tolerant of drought, flooding, are highly tolerant of saltwater, and they are extremely tolerant of fire. Like other pioneer tree species, cabbage palms are likely to be found in places that are unfavorable for other tree species. Sea level rise has been flooding low-lying forests, killing trees and replacing them with salt marsh. As the forests retreat landward, cabbage palms are the last trees to be killed.

Cabbage Palms along Sanders Creek. Emerging from a stand of black needlerush (Juncus roemerianus) in the marsh bordering the tidal creek, these cabbage palms display their tolerance for flooding and for saltwater. Nearby can be seen a few individuals of eastern redcedar (Juniperus virginianus) on higher ground, but the palms are clearly more tolerant of the harsh conditions in this area. This idyllic view of the creek can be seen from the Dixie Mainline, an old logging railroad bed repurposed as a road on the Dixie County side of the Lower Suwannee National Wildlife Refuge.

 

Sea Level Rise. In this scene a stand of cabbage palms occupying what was formerly a low-lying island near Shired Creek on the Dixie County side of the Lower Suwannee refuge has been overtaken by the effects of sea level rise brought on by global climate change. Although tolerant of both saltwater and flooding, their tolerance has limits. As forest changes to marsh and marsh changes to open water cabbage palm is the last tree species to succumb to deteriorating conditions. Cabbage palms are also dying out in other places where sea level rise is eating away at the margins of high ground.

Survivors on a Tiny Island. The plants on this small island at the confluence of McCormick and Sanders Creeks demonstrate that in the marsh often only slight differences in elevation determine what can grow there. The cabbage palm is growing near the water’s edge, and black needlerush (Juncus roemerianus), amaranth (Amaranthus australis?), and saltwater falsewillow (Baccharis angustifolia) grow nearby. On what appears to be the highest point on the island, a stressed looking swamp bay (Persea palustris) hangs on.

Immolation and Resurrection. Cabbage palms are not easily killed by fire. The upper image, made in March 2019, shows a cabbage palm near refuge headquarters that was completely engulfed by a controlled burn a few weeks earlier. The lower image, made in May 2020, shows the same tree, having apparently recovered fully. In fact, the tree was so little troubled by the fire that it put out a seed head soon after the burn and before new leaves had come out.

Experts disagree on whether cabbage palms are tolerant or intolerant of shade. The answer is probably both; although they grow best in sites with full sunlight, they have adaptations to resist elimination by more shade tolerant trees. A young cabbage palm may endure heavy shade thrown by a closed forest canopy and hang on for many years, barely surviving until a tree fall provides an opening. Once exposed to full sun they grow rapidly to keep above their competitors. They rapidly colonize openings in forests and often grow on the edges of forests where ample light comes in from the side.

Along the Suwannee River. A stand of trees on the riverbank is overtopped by a few baldcypresses (Taxodium distichum) near the right center and a few cabbage palms toward the left. Both the cypresses and palms have compensated for their intolerance of shade by growing tall to remain above more tolerant species. As in other shade intolerant species, their leaves are near the top of the trunk; any lower leaves would be shaded out by the upper ones. Old cabbage palms also tower over other forest trees in many different parts of the Lower Suwannee refuge.

Close relatives of cabbage palms occurring locally include two shrubs, bluestem palmetto (Sabal minor), which grows in moist woods and scrub palmetto (S. etonia) which occurs on old sand dunes. Other shrub-like palms found locally are more distant relatives. Saw palmetto (Serenoa repens) is frequent and abundant, especially in pine flatwoods. Needle palm (Rhapidopyllum hystrix) grows as an understory in moist hammocks and has been recorded from the Waccasassa Bay State Preserve, also in Levy County, but has yet to be recorded from the refuges. Like cabbage palm, and unlike most palms, our four other species can tolerate occasional freezes.