Adonidia merrillii: Christmas Palm1
The Christmas palm, also known as the Manila palm, plays an important role in tropical landscapes because few other palm species are so well suited for small sites. This species is native to the Philippines but has been cultivated throughout the world's tropics for many centuries. It grows fairly quickly to a height of about 6 feet, but very slowly thereafter, retaining its proportions for a long time (Figure 1).
Eventually, Christmas palms can reach heights of up to 20, or even 25, feet, with trunks 5 to 6 inches thick and a canopy spread of about 5 to 8 feet. Although single stemmed, this species is often planted as multiples of 2 to 4 plants in a clump, which typically grow out from each other with gracefully curving trunks. Leaves are pinnately compound (feather-like) and about 4 to 5 feet long with strongly arching form, and leaflets are held in a V-shape along the rachis. The flower stalks are formed beneath the prominent crownshaft. Clusters of bright red fruits, each about 1.5 inches long, ripen in late fall to winter, giving this palm its common name of Christmas palm.
Christmas palms are considered to be cold hardy down to about 30°F or USDA zone 10b. They are fairly drought tolerant once established and are moderately tolerant of salt spray on their foliage. This species is very well adapted to Florida's nutrient-poor soils and seldom displays any nutritional deficiencies. Occasionally, boron (B) deficiency symptoms are observed. Symptoms of B deficiency in Christmas palm include small, malformed new leaves, multiple unopened spear leaves, and sideways growth (Figure 2). For more information about B deficiency in palms see Boron Deficiency in Palms. When Christmas palms are planted as multiples, it is not unusual for one of the plants to be shorter than the others, exhibit a micronutrient deficiency, or even die due to slightly deeper planting depth or competition among the individual plants constituting the clump (Figure 3).
Christmas palms require little maintenance once established. These palms are self-cleaning, meaning that once an old leaf has died, it will drop off cleanly by itself. However, unless the attractive red fruits are desired, it may be advisable to cut off the flower stalks before they develop fruits, which will eventually fall to the ground and create a mess beneath the palm. Although often unnecessary, optimum growth and quality can be maintained by regular application of an 8N-2P2O5-12K2O-4Mg plus micronutrients palm fertilizer. See Fertilization of Field-Grown and Landscape Palms in Florida for more information about palm fertilization.
Although Christmas palms are relatively disease free, one disease, lethal yellowing, has greatly reduced the popularity of this species. This disease, caused by a phytoplasma (a type of bacteria without a cell wall), causes wilting and discoloration of the foliage before the spear leaf and bud eventually die. Often, the oldest leaf on affected palms will be kinked in the middle (Figure 4). There is no curative treatment for this disease, but it can be prevented by trunk-injection of the antibiotic oxytetracycline. For more information about this disease, see Lethal Yellowing (LY) of Palm.
Like all palms, Christmas palms are susceptible to ganoderma butt rot, a fungal disease that causes an internal decay of the lower portion of the trunk. The pathogen, Ganoderma zonatum, often, but not always, produces a fruiting body called a conk on the lower part of the trunk. If seen, these conks should be removed immediately to prevent spore production which can spread the disease to other palms. For more information about this disease, see Ganoderma Butt Rot of Palm.
Elliott, M. L., T. K. Broschat, J. Y. Uchida, and G. W. Simone, eds. 2004. Compendium of Diseases and Disorders of Ornamental Palms. St. Paul, MN: Amer. Phytopath. Soc. Press.
Meerow, A. W. 2006. Betrock's Landscape Palms. Hollywood, FL: Betrock Info. Systems.