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Monday, February 28, 2011

Florida's Palms

Royal palms (Roystonea regia) at the Four Arts
Center in Palm Beach. Regal!
What would the Florida landscape be without our palm trees? Those gracefully curved trunks and topknots of fronds are mainstays of any tropical setting. While many palms serve as trees in the landscape, they are not true trees, botanically speaking, because they don't have a cambium layer under a coating of bark and cannot develop annual layers of wood like actual trees. Palms are monocots and are more like grasses. A cross-section of a palm shows a curly or random fibrous grain rather than annual rings. This arrangement of woody tissue is usually quite flexible, making palms an excellent choice for wind tolerant landscaping.

A palm cross-section shows that there are no annual
rings and no true wood--just a fibrous mass.







After a palm seed sprouts, the plant goes into the establishment phase for several years when it looks and behaves like a shrubby palmetto. This time is necessary for the development of its growing tip and for the establishment of the tree trunk's diameter prior to its vertical growth. Once its trunk is established, then the palm starts growing vertically. The trunk doesn't increase much in girth thereafter. Almost all of the cabbage palms used for landscape plantings are transplants from the wild, because they take so long to get started.

Palm vs. Palmetto

At the front of this thicket is a young cabbage palm, while the larger
plants are saw palmettos.
The cabbage palm (Sabal palmetto), our state tree, is closely related to the blue palmetto (S. minor), but not the saw palmetto (Serenoa repens), which belongs to a different genus. The scientific name of the cabbage palm, which includes the term "palmetto," confuses the issue of palm vs. palmetto. Generally, a palmetto is a shrubby plant. The trunk of a mature palmetto isn't usually vertical for more than few feet. The fibrous palmetto trunk grows either underground or it lies on top of the soil while palms eventually develop vertical trunks. While a palm tree will look much like a palmetto while it develops a trunk, you can identify whether it’s a palmetto or a palm by the shape of the fronds.

A cabbage palm frond.

Palm Parts

Palm leaves, known as fronds, grow only from the terminal bud atop the trunk. There is only one terminal bud per trunk, so if the stem of a single stem palm is damaged, the entire plant will be killed. Depending upon the species, as the fronds die they may leave a persistent petiole, or leaf stem, known as a boot. Florida’s state tree, the cabbage palm, often has boots adorning its trunk. They provide habitat for birds and growing perches for ferns or epiphytes such as orchids or bromeliads. In south Florida, boots may also host a strangler fig (Ficus aurea) seedling that might eventually engulf the palm.

Cabbage palm boots

The palm roots are different, too. Palms have hundreds of thin roots originating from the trunk and most palm roots do not expand in girth or branch. A palm won't disturb sidewalks, roads or other hardscape features like a true tree because the roots cannot expand. Usually when palms are transplanted, they will develop all new roots from the trunk. This is why they usually are staked for six months or more when planted. Until new fronds start to grow, a newly planted palm tree will need additional water over and above the general landscape irrigation. After they are established, most palms are quite drought-tolerant.

When you see truckloads of palms, they have proportionally small root balls for the size of the trees and they have most of their fronds trimmed off. This way the roots do not have to support a full complement of fronds while they are trying to grow anew from the trunk. At no other time should a palm be treated in this way: once it’s established in your landscape only have the dead fronds trimmed away—never the green ones.

Because palms and palmettos do not produce wood like true trees, they cannot seal over wounds like true trees and any gouges in the trunk could become entry points for insects, fungi, and even small animals. To keep your palms strong, replace about 18 inches of lawn around the trunks with mulch, but don't pile it against the trunks. This mulched area also makes mowing easier.
Palmetto trunk running along the ground.

Choosing Palms to Plant

Do some research before you purchase palms to ensure that you select those that suit your climate and specific growing conditions in your landscape such as sun exposure, salt spray, and soil moisture. Our native cabbage palm is usually the best choice in northern half of the state, but there are several other palms native to south Florida. Be sure to avoid the queen palm (even though it’s widely available) because it’s not wind tolerant like most other palms and cold snaps will kill back much of its foliage. Queen palms are also invasive in parts of south Florida.

Choose the correct size for your space. While the palms may be tolerant of being close to buildings, make sure you leave adequate space for the tree's growth. You surely don't want to ruin your roof or your palms by planting them so close to your house that the fronds scrape the walls or roof.

Saw palmettos create a tropical feel and a coarse texture
in this florida landscape.
Palms: Tropics in Your Landscape

So plant some palms in your landscape for some coarse texture and to create a tropical feel. Choose species that are native to your region, water them liberally while they become established, trim away only the dead fronds, and you’ll find that palms and palmettos are a wonderful drought-tolerant and wind-resistant addition to your yard. FNPS likes palms and palmettos so much, that a palmetto
frond is our logo.


Ginny Stibolt


Cabbage palm at Heathcote Botanical Gardens in Ft. Pierce.
Notice anything weird??  It has three heads--very rare and
probably caused by an injury long ago.

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