Around Jupiter in a couple sites are huge ancient Live Oaks. Odd that some of don’t have many epiphytes (mainly tillandsias, ferns, and occasional orchids) riding up on their branches. Others are overwhelmed. In Riverbend Park just west of Jupiter there’s a stand of magnificent live oaks, including the “Tree of Tears,” allegedly watching over the Battle of the Loxahatchee in 1838. Several of the big old oaks in the park are covered with the Bromeliad known as Southern Needleleaf, Tillandsia setacea.
When I say covered, I mean blanketed, coated, festooned, dripping, and smothered, the bromeliads jammed edge-to-edge on every surface except the trunk and main vertical stems. The tillandsias are like frosting on a cake on tiny twigs and massive branches alike, sun and shade, toward the inside of the trees, and the periphery.
Let’s make a fake ballpark calculation. Suppose a big old live oak has 10 major branches, and each of those has 10 secondary branches, and each of those 10 minor branches, and each of those 10 branchlets, and every one of the branches and branchlets hosts (easily) 100 tillandsias, the imaginary tree has 1 million hitchhikers, and I’ll bet that estimate is low. Even if our math is dubious and dirty, you get the idea. To continue to speculate, say each tillandsia weighs on average 2 ounces, we then have 62 tons of Tillandsia setacea on one tree, and that is not counting soaking wet in a strong wind, nor the decayed leaves at the base of the tillandsias.
That’s a lot of biomass, and it isn’t just sitting there doing nothing. Any botany textbook will tell you in simple terms that epiphytes are not parasites…they are just getting a free perch “at no cost” to the host tree. That that may not be always accurate is largely untested. Botanists back in the 70s David Benzing and Jeffrey Seeman wondered if certain Florida bromeliads…Spanish-Moss and Ball-Moss, were parasites on their host trees. They checked to see if the roots penetrated or choked the oak bark, and the answer was “no,” but what they found was arguably more significant, if not surprising. The epiphytes are parasitic in their own fashion.
Live oaks tend to live in nutrient-poor soils where they depend on recycling essential nutrients from their own dropped leaves. But what if somebody steals those essentials before they hit the ground? Although not much studied, Tillandsia setacea has what you might call a “trashbasket” leaf collection system (discussed in an earlier blog) where its clustered knitting-needle leaves trap falling debris, such as oak leaves. The falling leaves compost in the company of an arthropod fauna, in the tree presumably nourishing the Tillandsia way up in its perch. The Tillandsia additionally has absorbent leaves able to capture dissolved nutrients from stemwash and drip-through, before they percolate to the oak roots. Benzing and Seeman concluded that the nutrient theft is sufficient to cause decline in the host tree. You might say, well, eventually the Tillandsia dies, and that would return the critical elements to the soil. True, in part, but 62 tons of organic matter tied up in an uninvited guest shading your branches is a lot of your own flesh & blood tied up permanently useless to the tree. And some of that escapes altogether as the Tillandsia disperses seeds onto the wind. The oak is feeding an ever-growing massive “tapeworm” on its branches.
(Thank you to everyone who ordered a weed book!)
To dig deeper on parasitic tillandsias CLICK. Here are a couple snips from that article:
John Bradford
George Rogers
George Rogers
Dee Staley
Treasure Coast Natives 
Steve Woodmansee
December 7, 2020 at 7:35 am
Hey George, Have you ever notice how many native trees have peeling bark? Gumbo Limbo, Mastic, Pigeon Plum, and many more have bark that peels off the trunk and limbs. Could this not be an adaptation to “discourage” epiphytes from growing on their limbs/surface? Great article!
George Rogers
December 7, 2020 at 7:36 am
Hi Steve…thanks, great point, and totally agreed.
Harvey Bernstein
December 7, 2020 at 11:29 am
Perhaps it’s a zero-sum game, overall. The tillandsias sequester nutrients that otherwise would go directly into the ground. When they die and decay, being heavier than oak leaves, they tend to drop closer to the root zone of the host tree, rather than being carried some distance by wind. Mature oaks also drop plenty of their own dead branches, presumably ones that are also tillandsia-covered.
George Rogers
December 7, 2020 at 3:48 pm
You seem to have missed the point. At any moment an enormous portion of the nutrients the tree has lifted up to its canopy are tied up in a huge population of a permanently out-of-reach “parasite” population. I am not aware of any reason to believe oak leaves to blow away more than do young Tillandsia plants and its many seeds. Also not known are the limits of the root zone of a multi-hundred year old live oak, which may be considerable. Falling limbs would be negligible relative to what is sequestered in the living epiphyte population. The actual data are in the Benzing & Seeman paper which I attached to the blog precisely for any reader wanting to get busy on details. Tacked on at the end of the blog are a couple snippets from the article. In short, it a big proportion of the nutrients in the system are tied up, even if in a dynamic flux, those nutrients are lost to the host tree. The nutrients in the tree’s realm are a finite pool, shunting a third of that pool aside will cost the tree.
Harvey Bernstein
December 7, 2020 at 4:07 pm
Definitely general speculation on my part. Also, many times what seems obvious isn’t what’s happening. It would be great if there would more research on this.
theshrubqueen
December 7, 2020 at 1:28 pm
Hmmm, I like the peeling bark theory. And the zero sum, maybe they are partners. I forgot all about the weed book – did not get one..need to.
George Rogers
December 7, 2020 at 3:49 pm
Peeling bark may be a general adaptation in some trees to minimize epiphytes, but when you are frosted in a coating of epiphytes, it didn’t do the trick on the tree in question.
theshrubqueen
December 8, 2020 at 4:46 pm
Definitely and does not explain River Birches..
Linda Grashoff
December 18, 2020 at 7:04 pm
I’m sorry I’m only responding to your blog post now. I’ve never seen so many epiphytes on one tree. Wow. I enjoyed your animated discussion. So how are these big old oaks doing? They’re OK? (It was fun to read my husband’s name in this post, BTW.)
George Rogers
December 29, 2020 at 7:32 pm
Hi Linda, Amazing load of epiphytes-eh? The historic tree, the “Tree of Tears” in that stand, dubiously reputed to have overseen the battle of 1838 is in a bad way losing massive patches of bark and dropping limbs….not sure you can blame the tillandsias. The likewise large old neighbors seem to be faring better.
jbarth2
February 24, 2025 at 8:21 am
This is definitely a parasite.
Among 70 crepe myrtle trees of 12' height, a cluster of stunted trees was found to be infested with these and may be recovering since their removal. A hedge of 2' - 3' schillings hollies below the infested trees was also infested: some died and others are recovering since the parasites were removed.Still trying to find out how they spread, and whether the similar-looking but tiny 1/4″-1/2″ sprigs sometimes associated are the younger version or a distinct parasite. They too are associated with dead branches. But the needleleaf sometimes has just one or two needles, so it could start out that way.