Tree of the Week: Louisiana Palmetto (Sabal minor)

The Centenary arboretum is home to innumerable Louisiana, or dwarf, palmettos (Sabal minor). These evergreen fans are primarily found in the low, wet areas, densely crowding the upper and lower ponds. However, a couple of volunteers have sprouted and developed in drier spots.

In this photo, we have two distinct, massive Louisiana palmettos flanking a smaller volunteer. The two large individuals are held responsible for the countless palmetto volunteers. They are more than 30 years old, having entered the collection in 1988, when Professor Ed Leuck brought back two seedlings from the Caroline Dormon Nature Preserve, located in Bienville Parish.

The two seedlings grew up in wet conditions. They were planted next to the arboretum drainage channel, on the north side of the upper pond, under the partial shade of an old, on-site native white oak (Quercus alba).

Over the course of three decades, these Louisiana palmettos have developed substantial, sloppy trunks, which are uncommon for the species. Much has been discussed about whether palmettos such as these are in fact something other than Sabal minor. For now, they are considered a specific growth form of Sabal minor. These are Sabal minor caulescent (with a trunk).

A leaf was trimmed from each trunk for inspection. These are heavy leaves, with wide fans and long petioles. The two leaves have very similar measurements. Petioles are nearly 5 feet long. Leaf blades measure more than 4 feet long, and more than 6 feet wide.

For comparison, two leaves were trimmed from two different sabal palms (Sabal palmetto), both approximately 20 years old.

LEFT: Louisiana palmetto
RIGHT: sabal palm
Sabal palm leaves are larger with longer petioles. We also see two distinct leaf shapes.

Louisiana palmetto leaves are flat and fan-shaped.

Sabal palm leaves have a wild appearance. The leaf blade is distinctly not flat.

The two different species also exhibit an interesting difference in their petioles. This is a Louisiana Palmetto petiole. Can you see how it twists?

The sabal palm petiole is uniformly straight.

For more information about this species consult the following:
Loyola University New Orleans
Louisiana Plant Identification and Interactive Virtual Tours (LSU AgCenter)
"A Taxonomic History and Reexamination of Sabal minor in the Mississippi Valley"