Plant classification is a subject only a plant lover finds intriguing. Within the United States public school systems, we were all once exposed to the distinctions between the plant and animal world and yes, we were once taught about domain, kingdom, phylum, class, order, family, genus, species – the taxonomic description of life forms. It was something we had to learn, then we promptly filed it away, never consciously using it again, unless our future led us into the world of science.
I did choose science or perhaps, science chose me. Anyway, I had a love of plants and the outdoors, and an early college counselor suggested a career in landscape horticulture. My first classes about plant morphology (outward form and external structure) and anatomy (internal structure) opened up a fascinating world of order, revealed in the lab using dissecting tools and microscopes, and in field exploration outdoors with hand lens and the senses of taste, touch, smell and sight. Plant identification was a challenge that I embraced; to this day, I still bring home the unknown specimen to study and analyze. Friends know I will readily search for an answer to “What is this?”
Yet, if you think about it, all of us use some type of classification as we look around us, whether it is in the plant or animal kingdom. So, let’s talk about the plants you see. Your brain says tree, flower, grass, shrub. If you live in Coastal Georgia, you subconsciously know the difference between a pine and an oak and yes, a palm. You group them by the similarities that you see, be it the shape, the form or the leaves. And if you were to go back to fifth grade biology books, you would see that conifers, such as pines, are gymnosperms that produce “naked” seeds that are not enclosed within a fruit (think pine cone). The flowering plants, grasses, trees and palms are angiosperms, producing flowers and seeds enclosed within a fruit (think peach). They further separate into dicots (two embryonic leaves, leaves with netlike veins, flower parts in fours or fives, vascular bundles in a ring around the stem and taproots) and monocots (one embryonic leaf, leaves with parallel veins, flower parts in threes, vascular bundles spread throughout the stem and fibrous roots). An oak tree is a dicot; grass is a monocot. And a palm, well, it is also a monocot. But from there on, a palm is very different.
Dicots and conifers produce lateral meristems that grow in different directions from the trunk resulting in what we call branches. However, palm stems have a single growing point known as an apical meristem. A palm species can have a single stem or multi-stems but they do not have branches growing outward from the stem. They can only grow the stem upwards in height. This apical meristem or growing point is often referred to as the bud or heart. All new leaves and flowers develop from the heart. Death of the heart of a palm results in death of the entire palm in a single-stem species and the death of the one affected stem in a clustered species. In addition, any wound to the trunk is permanent whereas wounds in dicots and conifers will heal because the lateral meristem produces vascular tissue and bark that will grow over the stem wound. Protecting the heart of the palm, then, is crucial!
What damages the heart of a palm? The first thing that comes to mind is injury in transport where an improperly secured palm bounces back and forth on a truck and winds batter the plant. The second is the impact of improper pruning off of older palm fronds. When old fronds are removed that leave existing fronds that form a V-shape along an imaginary clock face between 10 a.m. and 2 p.m., rather than fronds that form a half circle along an imaginary clock face between 9 a.m. and 3 p.m.; too many have been removed. This allows for greater stress on the heart of the palm in high winds. The removal of older fronds also takes away available mobile nutrients that the palm can and will use when nutrient deficiencies occur; a starved heart becomes weak, producing less new fronds critical for plant vigor. Remember, a palm has only one area of growth – that precious apical meristem or heart. The third is insect damage to the heart such as giant palm weevil (a great threat to Bismarck palm, Bismarkia nobilis, and Canary Island date palm, Phoenix canariensis; and a lesser threat to sabal palm, sabal palmetto.) The fourth is not proven, but damaging winds from hurricanes may also be a cause of death of a palm heart.
What does an injured apical meristem look like? You will see brown foliage (dead fronds) in the center of the stem at the very top and no new growth. If a newly planted palm (whose fronds are often cut off completely before transport) does not push out any new growth after proper planting and watering, then the palm has had critical injury to the heart and is dead. Fifteen percent of all palms will die outright at transplanting because the heart has been injured or the roots don’t rejuvenate after being cut way back in preparation for transplanting (a common practice since the existing fibrous roots often dry out during transport anyway). Please note that it is normal for older fronds to die after three or four years, eventually dropping downwards towards the trunk. These do not harm the palm nor do they indicate that the heart is not healthy. They can be removed for aesthetic reasons.
A palm is a big investment in a landscape and can often cost thousands of dollars. Be sure to use a reputable firm that offers a minimum one-year warranty on the palm they provide. Be sure palms are watered every day for the first week, then tapering off the water to allow for enough to keep the soil a bit moist but not wet. The very best time to plant palms is in the spring, when ground temperatures are 70 degrees F or above, before it gets too warm. Spring provides the optimum temperatures for root growth, so necessary to replace the roots cut off in transplanting from the field to the landscape site. Tall palms above 8-feet in height are best braced at time of planting, and all reputable companies know the proper method. A web search will provide pictures. No staples or nails that penetrate the truck should be used. Bracing can be removed after two full growing seasons depending on site location. If in a high wind area, bracing can remain for two years.