Sabal

Liliatae; Arecidae; Arecales; Arecaceae (Sabal Palm)

Sabal palmetto hammock at Yankeetown, FL. Photo by D.M. Jarzen

Palms are a familiar and characteristic feature of most tropical and some warm temperate landscapes. They occur in habitats ranging from the mesic forests of southeastern United States, rainforests of the Americas and Southeast Asia, to many of the tropical deserts and savannas of the world. To some cultures, such as those of the Middle East, southwestern Asia, and northern Africa, the presence of palms is equated to life since these trees occur only at oases, often the sole sources of water in the region. In other parts of the world palms are equally as important as a source of food, shelter, furniture, and clothing. In the Plant Kingdom, palms are eclipsed by only the grass family (i.e. grains) in importance to the lives of humans. The palms are a unique group of monocotyledons, with distinctive trunks, leaves, and flowers. Approximately 300 genera with about 2650 tree and liana (vines) species are broadly distributed over the tropical and warm temperate regions of the world.

Life History The genus Sabal, commonly called palmetto palms or hat palms, consists of 16 species that occur from the coastal regions of southeastern United States, west to northeastern Mexico, Bermuda, some Caribbean Islands, Panama and northern South America. They usually live in open habitats, such as coastal dunes and tidal flats, and savannas, but also occur in shaded swamps. Some species, such as the dwarf palmetto, Sabal minor, have a subterranean trunk, leaving only the crown of the palm above ground. Sabal species can be difficult to identify as hybridization occurs frequently, particularly in cultivated populations. The flowers of Sabal species are bisexual, pollination usually occurring with the aid of insects. Wind may also assist in pollination. Seeds are often dispersed by birds and small mammals that feed on the prolific numbers of fruit produced by mature trees. Germination occurs in the soil within 2 - 3 months. The sabal palm, Sabal palmetto, also known as the palmetto palm, cabbage palm, and Carolina palm, usually occurs near the coast from southeastern North Carolina to the Florida Keys, west along the northern Gulf of Mexico, Cuba, and various islands of the Bahamas. It is considered one of the most common species of native trees in North America. It occurs along sandy shores, commonly in crowded groves, as islets in vast expanses of salt marsh grasses, and in inland hardwood hammocks. Since it occurs further north than most other New World palms, the sabal palm is relatively cold-tolerant and hardy, making this species a favorite with home owners and landscapers. To meet the ever-increasing demand for this ornamental tree, the species is widely cultivated and several varieties are available through commercial outlets.

Distribution of genus Sabal after Zona, 1990. Sabal palmetto hammock at Yankeetown, FL. Sabal palmetto. Two forms of trunk condition. Sabal leaf.

Evolutionary History

Palms are an ancient group of woody monocotyledons assigned to a single family, the Arecaceae (or Palmae). They form a natural group based on their many shared characters, such as the usually distinctive leaf and fruit morphology. Palms are frequently identified from fossil floras from these unique and easily recognizable features. The earliest known palms are leaves (fronds) described as Sabal magothiensis and stem parts referred to Palmoxylon cliffwoodensis recovered from several localities along the Atlantic Coastal Plain from New Jersey to Georgia. These early palms are dated as late Cretaceous (80 mya). Since these earliest fossils are immediately recognizable as palms as we know them today, it can be theorized that this unique group evolved earlier than the fossil record presently reveals.

The palm family has been divided into six subfamilies, each further subdivided into a number of smaller groupings (tribes and subtribes), based on unique morphological characters, such as leaf shape and folding. The most recent taxonomic revision was completed in 1987 by N. W. Uhl and J. Dransfield of Cornell University, Ithaca, NY (see Selected Bibliography).

The genus, Sabal, is assigned to the Coryphoideae, a pantropical (throughout the tropics) subfamily of palms consisting of about 32 genera and 322 species.

Biogeographical History

Palms have a long and diverse fossil record in many parts of the globe. The mangrove palm, Nypa fruticans, still living in Southeast Asia, is recognized from rocks dated about 69 million years old (latest Cretaceous of Borneo) solely from its distinctive pollen features. This same species, as well as several other genera occurring only in the Tropics today, including Sabal, have been collected from Eocene sediments near London.

In North America, fossil leaves of Sabal have been discovered from the Paleocene (about 59.0 mya) of Montana, Wyoming, Colorado, and New Mexico, from the Eocene (about 39 mya) of Tennessee, and the Oligocene (about 27 mya) of eastern Texas. The occurrence as fossils of this tropical and temperate group in regions far to the north of their present distribution strongly suggests that much warmer conditions existed in these areas in the past. The Sabal specimen illustrated here is from Miocene deposits of northwestern Florida.

Conservation Efforts

Habitat destruction has probably caused the extinction of nine species of palms in the last few decades. Sabal miamiensis, described in 1985, is now extinct because of loss of habitat due to urban sprawl. Many other species face a similar fate if controls are not put in place to curb habitat loss and collection for food, crafts (i.e. hats and baskets), and building materials.

Although Sabal palmetto is not a rare or endangered species, related species are indeed threatened and require conservation efforts to insure their future. Isolated in a bend of the Rio Grande River along the United States and Mexican border, the Sabal Palm Audubon Center and Sanctuary harbors one of the most beautiful and critical ecosystems of southern Texas and northern Mexico. The Texas palm (Sabal texana, referred to as S. mexicana by some authorities), also known as Texas palmetto, Rio Grande palmetto, palma real, and palma de Micharas, is a native of the lower Rio Grande valley. This species once grew profusely along the banks of the Rio Grande in small stands or groves extending some 80 miles upstream from the Gulf of Mexico. With increased human population pressures and changing land-use policies, today only a small portion of the forest remains, protected by the Audubon sanctuary.

Floridians and visitors to Florida are fortunate to be able to visit the Fairchild Tropical Gardens in Coral Gables, near Miami. Here scientists carry out research on a variety of palm species, with an emphasis on conservation and improved horticultural varieties for the home and garden.

History of Specimen

Frond Fossil.

In late 1990 staff members of the Florida Museum of Natural History excavated a nearly complete frond of Sabal sp. (UF 18049-29145) from the banks of the Apalachicola River near Alum Bluff in northwest Florida. This classic Miocene (Chipola Formation, 16-18 mya) exposure is well known for its great diversity of fossil mollusks, corals, microinvertebrates, and plants. This unique specimen is a compression consisting of most of a single frond (leaf), preserved in a coarse sandy sediment. The matrix (surrounding rock material) is very loosely consolidated, and easily breaks apart with repeated handling. The specimen was prepared with a dilute mixture of toluene and Acryloid B-72™ (ethyl polymethacrylate) to harden the surface so the fossil could be safely examined.

Kitsch Korner

Florida State Seal, featuring a Sabal palm. The South Carolina State flag, featuring a Sabal palm. A chickee hut.

An image of a palm tree evokes a sense of tropical paradise. The beauty and recognition factor of this distinctive image has led both Florida and South Carolina to name the sabal palm as their official state trees. In South Carolina the tree is also symbolic of the defeat of the British fleet at the fort, built of palmetto logs, on Sullivan's Island. The sabal palmetto has been used by humans in many ways for perhaps thousands of years. The fruits have been credited with the ability to improve the digestion of native people in southeastern United States. Early human inhabitants of Florida had a variety of uses for the sabal palm. The bud of the tree was eaten as food, the fibrous trunk was used for shelter materials and the large, thick fronds were used as roofing material. Still today, Native Americans in south Florida use the sabal palm to build chickee huts, shelters with water tight palm-thatched roofs and constructed with hand-hewn logs without the aid of any kind of metal, including nails. The large leafbud (the "cabbage") is still highly prized by many Floridians and visitors as a salad vegetable and for making pickles or relishes. However, this practice is not condoned by many since the palm must be destroyed and takes many years to be replaced. Recipe for Taal-holelke (Boiled Swamp Cabbage) The following recipe comes from the Seminole Tribe of Native Floridians. Cut out the heart of the cabbage palm. Strip off the outer hard tough fronds to reach the actual white heart. This is the most tender part and should be cut into 1/2-inch strips or cubes. Cook slowly in very little water for 20-30 minutes, adding two tablespoons of cane syrup or sugar and salt to taste. Stir frequently to prevent sticking. (Swamp cabbage appears on your grocery shelves as "Hearts of Palm.")

Bibliography

Brown, K. E. 1973. Ecological life history and geographical distribution of the cabbage palm. MS Thesis, North Carolina State University, 101p.

Graham, A. 1999. Late Cretaceous and Cenozoic History of North American Vegetation North of Mexico. Oxford University Press, New York, 350 p. ISBN 0-19-511342-X.

Jones, D. L. 1995. Palms Throughout the World. Smithsonian Institution Press, Washington, DC, 432 pp. ISBN 1560986 166.

Manchester, S. R. 1996. Petrified woods in Florida. Papers in Florida Paleontology, Florida Paleontological Society, Number 8:1-8.

Oehlbeck, B. 1997. The Sabal Palm: a native monarch. Gulfshore Press, Naples, Florida, 86pp. ISBN 0-9654019-0-1.

Scott, T. M. 1997. Miocene to Holocene history of Florida. In: Randazzo, A.F. & Jones, D.S. (eds.) The Geology of Florida. University Press of Florida, Gainesville, pp. 57-67. ISBN 0-8130-1496-4.

Stevenson, G. B. 1996. Palms of South Florida. University Press of Florida, 251 pp. ISBN: 0813014417.

Uhl, N. W. & Dransfield, J. 1987. Genera Palmarum: A classification of palms based on the work of Harold E. Moore Jr. International Palm Society and the Liberty Hyde Bailey Hortorium at Cornell University, Ithaca, NY, 600pp. ISBN 0935868305.

Zona, S. 1990. A monograph of Sabal (Arecaceae: Coryphoideae). Aliso 12(4):583-666.

Zona, S. 1997. The genera of Palmae (Arecaceae) in the southeastern United States. Harvard Papers in Botany 11: 71-107.

Links

Fairchild Tropical Gardens, Coral Gables, FL - http://www.ftg.org/

International Palm Society - http://www.palms.org/

Sabal Palm Audubon Center and Sanctuary - http://www.audubon.org/local/sanctuary/sabal/

Seminole Tribe of Native Floridians - http://www.semtribe.com/culture/recipes.shtml/

Excellent photographs of Sabal palmetto are found at: - http://www.plantapalm.com/vpe/photos/Species/sabal_palmetto.htm