A TREE TALK WITH MASTER ARBORIST MICHAEL MURPHY
Story by Carolyn Males
Palm: from the Latin palma (hand) a tree with a leaves/fronds that resemble a hand’s spread fingers.
Once again, master arborist Michael Murphy and I meet up beneath a canopy of live oaks, this time on the Bluff in Beaufort. But today we’re not here to talk about these leafy giants. Instead we’ll focus on palm trees. With more than 2,600 species worldwide, we’re narrowing our discussion to the sabal palm or palmetto, the state tree of South Carolina, a cold-hardy variety that thrives here.
In front of us along the waterfront stand several palmettos: some perfectly groomed, some scalped and others clustered with vines. Behind us along Bay Street a dozen or so flank a row of historic houses. Problem is, these palms may be doomed by their proximity to the overhead power lines and Dominion Energy’s plans to take down trees they’ve deemed hazardous. In this case that means palms with fronds that could entwine into the wires, causing outages. But strangely, the crowns of this particular grouping have angled away from those overhead cables. Could that save them?
It’s here that Murphy begins today’s lesson, one he refers to as Tree Truths and Frond Facts.
[LOCAL Life] This row of palmettos along Bay Street is so iconic. Even the odd bend they take adds to their picturesque beauty. [Michael Murphy] Palms are negative geotropic — that means they grow directly away from the earth. So the way these palmettos grew straight but then took a hard right isn’t typical at all. Every once in a while you see something like that, but this is a whole row of them. Maybe at one point a big wind tipped them and they veered away from the power lines. So these may not be on Dominion’s current hit list. By the way, the roots of these palms, on the other hand, are geotropic. They grow down into the soil. This means if you bend these big grass plants over, they’ll want to grow straight again.
[LL] Big grass plants? [MM] Palms really aren’t trees, per se. They’re monocots while every other tree is a dicot. Monocots have a single cotyledon or shoot-like blade of grass that sprouts from their germinating seeds; dicots have two cotyledons. Along with palmettos, bamboo and yucca are the only two other plants in the monocot family that have any tree form to them. To add to the confusion, there are palms that aren’t palms, like the sago palm which is really a cycad, more related to pine trees.
[LL] Does that mean palms don’t have trunks like other trees? [MM] Unlike dicots such as these live oaks, palms don’t have their conductive tissue in a bark. Instead their conductive tissue is spread in a thin layer of fibrous bundles throughout a protective false bark. In other words, palmettos have a vascular system just like we do. But in their case, they have xylem tissue in their stems that brings water and nutrients up to the leaves and phloem which brings nutrients produced by photosynthesis down to the roots.
[LL] How does that affect the way they grow? [MM] When palmettos grow, they’re not like trees. They actually stay at ground level until they attain their diameter and then they start shooting up. A sabal palm that has all its fronds (measuring maybe ten feet across) and is popping up out of the ground, could be twenty-five years old. But it’s not going to get any height to it until its trunk reaches its full diameter which is about fourteen inches.They can’t be transplanted until they are eight feet tall. That’s when they get this maturation in them. That’s why if you find a shorty in the woods and you take it back and transplant it, even with a root ball, it will die. It has to be eight feet tall.
[LL] I’ve noticed that the fronds on newly planted palmettos are often sheared off into a feather duster shape. [MM] Palmettos don’t have to be trimmed back for transplanting. However, fronds can break when they’re being taken on and off the truck during transportation from Florida, so growers prune them back before loading. Doing that once isn’t going to kill them. They do recover, and fronds grow back. But if something happens –– if they’re not watered properly or air pockets are in the soil or they’re planted too deep –– they can die.
[LL] Planted too deep? [MM] Yes. For example, if you ordered a twelve-foot palm and installers can only find a fourteen-footer, they may plant it very deep so it looks like a twelve-footer. That tree won’t recover because sabals have to be planted at the same level they were growing on. So a damaged tree, feeding off stored energy and staying green, may look alive after two years. But if it still looks like a feather duster, it may be dead. That’s why you want a two-year guarantee.
[LL] Speaking of shearing, the roots of palmettos I see being transplanted don’t look big enough to support their weight. [MM] The roots, which are fibrous, are shaved off before they’re delivered because they’re not going to regenerate. Instead, new roots are generated from the bowl of the stem that’s planted underground. (By the way, this is true across many but not all palms varieties.) That means even with a big palm tree, you can still take a small root ball, and it will sustain itself.
[LL] Any growing tips for newly transplanted palmettos? [MM] They’re very easy to care for. But the main cause of failure for new transplants is water stress, either too little or too much. When they’re first planted, they have to be watered a lot, but you need to keep them well drained. Then gradually lessen the irrigation. After that first year when you see that new growth come up, you might not have to water them at all. They recover from transplanting quickly. Just make sure they’re planted securely in the soil.
[LL] What if a mature palmetto gets damaged? [MM] If there’s an accident and a car hits a tree like one of these live oaks, that tree will produce callous tissue which covers it up. You can come back a couple of years later and not see any of that damage. But a palm doesn’t have that capability. It needs its stem for structural support, but it won’t callous or seal if it’s wounded. That wound may lead to fungus problems, but it won’t kill it. After all, growers and landscape companies pick up palm trees with chains.
[LL] What about hurricanes? [MM] Our sabal palmettos are designed for hurricanes, especially if they are growing here natively or were planted a long time ago, because of that fibrous root system. If you hang around for a hurricane or if you watch it on weather channels, they always show the palms. The fronds are kind of big and spread out like this, [to illustrate Murphy holds out his hands and spreads his fingers] so when the hurricane wind blows against these palms, they fold their fronds into a point. [He puts his fingers together in a prayer position and holds them at an angle.] Back in 1989 during Hurricane Hugo all the leaves and Spanish moss blew off the oak trees, but none of the palms lost fronds except for the dead ones.
[LL] So they’re relatively hardy. [MM] Yes, they’re very salt tolerant and can grow close to the water’s edge. With no real competition, they grow wherever they need to. They don’t need rich soil like other trees, but they do have certain requirements on the micro-nutrient side. When you fertilize palmettos, you need to use one specifically formulated for them, lower in nitrogen and phosphorus but higher in potassium and other micro-nutrients. A lot of people are wasting their money on fertilizer, so do a soil test first.
[LL] Weren’t palmettos used to repel cannon balls during the Revolutionary War? [MM] You’ve got to read about Carolina Day and the Battle of Sullivan’s Island. That’s how the palmetto got to be the state tree. Back in the Revolutionary War, with the British Royal Navy on its way to attack Charleston, American forces used palmetto logs embedded in sand to barricade and shore up the unfinished fort. With British ignorance of the tides –– the water can get dead low –– and with their cannon balls bouncing off and being absorbed by the palmetto log walls, the battle was a major victory for the revolutionaries.
[LL] Let’s move on to aesthetics. When our palmettos were first planted, they were booted, but over time the booting has peeled away. [MM] Boots are remnants of old frond bases as the dead fronds fall off or are cut away. (Growers have a machine that can neaten them up and take off any loose boots before they’re transported.) Boots are sinewy and persistent, so most palmettos hold onto their booting for six to eight years. But the boots will get loose, and once they start to come off like that one over there, [He points to a palmetto by the water where pieces of its unfurling booting lie on the ground] there’s no way to keep them on.
[LL] And pruning? The crowns of a couple of palms along the bank here look like they’ve had very bad haircuts. [Murphy shakes his head.] You should prune palmettos so their fronds are no higher than the 9 or 3 positions on a clock. You want to leave a half circle of a nice crown and keep fronds that have any kind of green in them.
[LL] Even if they’re yellow? [MM] If there’s any green on the fronds, it’s best to leave them. They’re still producing chlorophyll and energy for the plant. You have to balance that against the beauty of having everything all green. A lot of times the homeowner is saying I want everything yellow cut off, and the pruner has to say that’s not good for the plant. And while pruning them off isn’t going to kill the palmetto, it can weaken it and possibly stunt it. In fact, palmettos never have to be pruned. You don’t have to trim them unless you want to neaten them up. They shed their deadwood. But even if a palm has been pruned, there are always going to be brown fronds hanging down with piles of debris beneath.
[LL] This palmetto over here is full of vines. Shouldn’t they be removed? [MM] Vines are invasive and can grow faster than the fronds, overwhelming the crown and blocking sunlight which fronds need for photosynthesis. Without that, fronds wilt and die. Because vines grow in a winding patterns, you can’t just pull them down. The remedy is to cut them close to the ground all around the base of the tree and then clip them again four or five feet up as well. That disconnects them. Afterwards, a pruner can remove the dead vines or you could just let them dry up and fall off on their own.
[LL] And what about those tiny cream-colored flowers on the branched inflorescence that show up in early summer? [MM] Palmettos flower in late June. Their blooms are great pollinators, and the bees love them. That’s fine, but you’ve got to prune the inflorescence before it fades or it goes to seed in mid to late July. Otherwise you’ll get hundreds of tiny palms sprouting up, and if you don’t get those out in the first year, it will be almost impossible to pull them out later. Pruning the brown inflorescence is almost like deadheading a flower. It’s not that we’re worried about the energy the plant is expending on producing seeds, it’s that we just don’t want their seeds spread around a garden area or yard. If you prune them then, you won’t have to do it again until the following year. Just make sure you’ve got your tree trimmer lined up.
As we leave I take one last look at the row of palms on Bay Street, hoping their crazy growth angle garners them a reprieve. Meanwhile I’m looking forward to that flowery show of inflorescence that will be sending the bees abuzzing in June. But armed with a bit more knowledge, I’ll be sure to schedule a spot on the landscaper’s schedule before the flowers turn brown and go to seed. LL