Epiphyte or parasite? What’s hanging out on my palm?
03/22/2014 12:00 AM
03/21/2014 4:38 PM
With spring in the air, young seedlings are looking for a home where they can spread their roots. While most seedlings find the soil a very acceptable place to live, some adventurous young sprouts are in search of something more exotic — maybe even your palm tree.
Some of these seedlings may make a perfectly suitable cohabiter and will keep your palm company on a lonely night, while others are not welcome and should be dealt with immediately. To distinguish between the two it is important to understand how they are using your palm. Identify the organism and then decide how to handle it.
Epiphytes use other plants only as a surface to grow on; they use your palm as support only. They are perfectly safe and may enhance the look of your palm.
Parasites, on the other hand, use other plants as support and steal nutrients or water from the host plant as well. These are the types of visitors you don’t want on your palm. If you have a parasite, you should remove it immediately.
When you see something growing on your palm trunk, first identify how it’s using your palm, then decide how to handle it. Here are a few common examples of epiphytes and parasites and recommended actions.
Ganoderma bud rot is an untreatable fungus that eventually kills its palm host. Spores of the fungus live in the soil, and palms absorb them through their roots. The fungus begins its mayhem by slowly rotting the trunk from the inside to the outside. After the damage is done, the fungus emerges as a conk on the outside of the trunk and starts to reproduce. The reproductive conk produces spores that spread to the soil, and the process begins anew.
By the time the conk emerges and you can identify the issue, the inside of your palm is rotten and the fate of your palm is sealed. It is nearly impossible to detect ganoderma bud rot until the conk emerges.
A healthy palm is less likely to get sick, so the best protection from ganoderma is to keep your palms on an appropriate fertilizer routine. If you do notice a conk, call a certified arborist immediately. Appropriate measures need to be taken in order not to spread the spores. Remember, since the spores live in the soil, any other palm that you plant in that location will most likely get sick. If you have to plant another palm in the same location, try a different species altogether.
Strangler fig, Ficus aurea, is a southern Florida native that can grow into a dreadful epiphyte. As a seedling it survives as an epiphyte and does not harm its host plant. As it grows, its roots reach the ground, and it begins to expand. Eventually, it strangles its host and survives as a free-standing tree.
Strangler figs are quite common along the streets in Miami. In palms, strangler figs start out in the old leaf scars, or “boots.” Early detection is key. When strangler figs are small, they are easy to remove. But, as they grow, they become more difficult to manage and can eventually kill your palm. They are especially common in our state tree — Sabal palmetto. Keep a ladder in your closet, a pair of clippers handy and be ready.
Lichens also live on palms but are not the least bit lethal. Lichens occur in all ecosystems, on all continents, and form the basic building blocks of ecological succession. Lichens are able to break down rocks to form soil substrate. But, on your palm, they are not decomposing rock, they are just looking for a place to hang out.
Lichens are usually whitish green and are on almost every oak tree in southern Florida. They pose no threat to our green giants.
In fact, lichens teach us a very good lesson of teamwork. Lichens are an amalgamation of fungi, algae and cyanobacteria, three very different organisms that must live together in order to survive. In most cases, the fungi provide minerals and water and the algae (or cyanobacteria) provide sugars and other carbohydrates. Do not fret over little green-white unifications on your palm. They are harmless.
Bromeliads, orchids and anthuriums also will find a way into the old leaf scars of your palms but they are harmless as well and, for the most part, live entirely as epiphytes. Some enthusiasts even place them in the palm “boots” and let them flourish. These kinds of epiphytes are treasured in most landscapes for their beautiful growth forms.
Tillandsia species are quite common, and some are native to Florida. Some tillandsias survive as tank epiphytes; they form a tank to hold and absorb water since their roots don’t have access to the soil. The cowhorn orchid is an endangered, southern Florida native that attaches to its host with white, clasping roots. If you find this beauty in your backyard, you are lucky indeed!
So before you get panicky about plants growing on your palm, remember that not all epiphytes are parasites. While some plants, like strangler fig, need to be removed, others, like the cowhorn orchid, are precious and should be coveted. So first, find out what the organism is. It could be something worth saving.
Sara Edelman is the palm and cycad manager at Fairchild Tropical Botanic Garden.
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