Handy definition: Rhizomes are underground stems, not roots. Roots grow from them.
Great oaks from little acorns grow. Quercus minima is great, although not great big. About knee takk tall, the mini “tree” isn’t as puny as it appears at a glance. It is hidden mostly underground as a rhizome system.
Its subterranean tastes tie in with its kinship. The closest relative to Dwarf Live Oak is Sand Live Oak (Quercus geminata) one of the dominant local scrub oaks. Capable of becoming a midsized tree, Sand Live Oak is most often encountered as a rhizomatous shrub. It and its sister Dwarf Live Oak have the leaves fuzzy beneath. The closest relative of this pair is Southern Live Oak (Quercus virginiana) we all know as ultimately a huge stately tree. Southern Live Oak often has root sprouts around the base, these often oddly similar to Dwarf Life Oak.
The species trio forms a progression of decreasing above-ground size and increasing rhizomes. Southern Live Oak, obviously the biggest, is not very tolerant of fire except for its invulnerable size, its under-canopy conditions, and its ability to resprout from roots. Does Southern LO have rhizomes? Big Southern LO don’t, but small shrubby ones can. That brings us to Sand Live Oak, ranging size-wise from trees to small shrubs, and they do have rhizomes. In the event of fire, Sand LO sprouts anew from its rhizomes. Sand LO bridges the gap between Southern LO and Dwarf LO. Rising from a sprawling rhizome system, Dwarf LO is a sand submarine with little green leafy periscopes with acorns.
Immature acorns seem well protected.
Yes, rhizomes are fire insurance, as many observers keenly point out. Stipulated, but are flames the whole truth? Oh, the things we don’t know! Dwarf LO grows in pine woods where burns are risky business, and it grows in scrub where fire is less dire, but where access to water is. Species in scrub have to drink from quick-dry sand, and/or from deep roots. Maybe the wandering Dwarf LO rhizome system is a dynamic water-gathering network?
Or maybe a fungus-assisted nutrient network? Fungal root associates (aka mycorrhizal fungi) help procure soil nutrients, and what better place to need nutritional facilitation than sterile sands? Oaks in general are well known for root-fungal symbioses, so is Dwarf LO underground a fungal-food network?
A person could say accurately that fire removes competition so that rhizome species can resurface open space after Armageddon. Yup, and another way to avoid bad circumstances is to relocate. A complex of wandering rhizomes allows for that—-drop away here, pop up there whac-a-moleishly.
In short, there’s no doubt of the obvious fact that going underground thwarts fire, cyclones, and meteor strikes. But the progression of the three oak sisters toward shrinking aboveground and increasing belowground also goes hand in hand with decreasing habitat quality in terms of water and nutrition. Which is more important…defense or infrastructure?
Really no take-home point to the short blog today, merely what it’s all about: joy in mingling this steamy afternoon in the Mangroves with Sulfur Butterflies dancing cheek to cheek in the sunflecks. A reminder to go out and cherish Creation even when it reeks like Mangrove mud.
Photos above by John Bradford
Whenever you get around mangroves you see Sulfur Butterflies (Statira Sulfur I think). Mangroves don’t actually attract these pale yellowish flutterbys, but rather the Coinvines (Dalbergia ecastaphyllum) around the Mangrove habitats are the points of interest. Coinvines may be sprawling prone on a brackish shore, or a tangly shrub all mixed up with grapevines and whoknowswhat, or when among large trees, large woody climbing lianas. Why are they so often by brackish water—even if not necessarily so?
Coinvines are Legumes, even though they don’t look like it. Not sure about the Sulfur Butterfly Family collectively around the world, but the Sulfurs I know prefer Legumes as larval hosts. For the Statira Sulfur (if it is that species) caterpillars, the Coinvines seem to be a preferred salad.
Walking where the Coinvines grow, look for ragged chewed Coinvine leaves. Aside from the present suspects, not much else eats Coinvine, it seems. At the edge of the munched area you can find the muncher loitering. Or maybe eggs.
Hurry up, and lay some more eggs!
BTW…added value extra bonus, not today, not the same species, but Sulfur chrysalids can be well disguised:
(Polygala smallii is a very similar rare species in SE Florida.)
Polygalaceae
Time for a fetching little wildflower in bloom now (and otherwise often) on exposed sands, mostly in moist shallow depressions. It’s a sunny eye-grabber out where much of the beauty is of a slightly harsher flavor.
Today’s photos by John Bradford.
Speaking of flavor, why the name “Candyroot”? The bruised root smells licorice- -ish. And how do we know that? The Seneca Tribe used similar Polygala species as medicines, most notably to treat snakebite. The flower clusters can look like rattler tails, thus the name “Seneca Snakeroot,” giving the genus Polygala the synonymous name “Senega.” That the fragrant roots are bioactive has long been known, involving the plants in commercial patent medicines. Don’t eat ‘em—polygalas contain toxins, including ones that irritate the digestive and respiratory system. The irritants include compounds known as “saponins”, and there’re is evidence of these stimulating milk production, potentially (speculatively) explaining the name “Poly-gala,” meaning “lotsa moo juice.”
What fascinates me about these little plants is their leafy rosette and skinny taproot. No need to dig one up….below is a photo of a museum specimen. Nobody to my knowledge has looked into Polygala rosette functions directly. So let’s play a natural history game. What is known about similar plants we can stretch extremely speculatively to today’s charmers?
Puny little root!
Does that spindly little taproot look capable of meeting the water and nutritional needs of all those rosette leaves? Accomplishing that is difficult in sterile loose sand drying quickly after rain. But maybe there is a supplement. Better known in deserts than in Florida scrub, some harsh habitat rosette plants harvest airborne water (including fog, mist, seaspray, dew, and drizzle) through their foliage. The rosette capturing water resembles The Dish capturing CNN, and the flattened leaves protect each other and the immediate ground from exposure. Some rosette water-catchers have tissue called “hydrenchyma,” expandable for hydro-storage. Polygala nana does have a hint of succulence.
Don’t get me wrong—I’m not suggesting Polygalas have any known carnivory (they do not), but come to think of it, the idea of taking in water and nutrients through rosette leaves brings to mind carnivorous rosette plants such as sundews and butterworts. Maybe these carnivores started out long ago in evolution absorbing water with dissolved nutrients, and became “so good at it” they expanded to taking in dissolved bugs.
Butterwort with its carnivorous rosette.
To sum it up, I’m just “trippin’” with all this, but even so, I’d bet a couple bucks that Polygala nana supplements its water and nutrient elements via the leafy rosette.
For a minor medical reason I’ve been housebound for several days. So no fieldtrips, but, then again, plenty of “fieldtrips” on the bookshelf and file photos in the archives. A mystifying new book is titled, “Unsolved Problems in Ecology.*” One of the head-scratcher chapters in it is, “What Determines the Abundance of Lianas and Vines”?
Oh yea, ha, ha, our little blog shall now answer answer one of the “Unsolved Problems in Ecology,” Not actually within our reach, but still fun to poke the conundrum here in vine-tangled South Florida.
Being a vine** is a great deal. You get a free ride up a tree into the life-giving sunshine without all the blood, sweat, and sap invested in building a tree. Vines can adjust their growth to seize the best canopy real estate. The puzzler is, if being a vine is such a bully deal, why aren’t there even more of them? Why do only some trees have climbers. What limits their abundance. It’s not from failing to get around, given that most Florida climbers have seeds rained down from perched birds. How convenient is bird delivery for establishing around tree bases?
Do vines help trees? The general consensus is, not much. There are some conceivable minor benefits, but most observers believe the net effect is negative.
Do vines hurt their trees? Yes, by stealing light, by root competition, as physical burdens, as wind-catchers, as entanglements with other trees, and sometimes as fire conduits. From a tree’s standpoint vines are green tapeworms. In fact, people who study vine infestations borrow statistical methods from medical parasitology.
Do some trees have more than one type of vine? Yes, frequently and dramatically. Inter-vine competition has never been studied much though. Hard to measure!
In a forest, do different tree species have different hosting tendencies? Yes but long story short, perhaps not as much as we might think, and trunk diameter matters too. Even Gumbo Limbo gets vines.
Do trees have defenses against vines? Yes, although not enough to answer today’s big question, especially because defenses can be bypassed by vine trickery. Examples of defensive measures please:
1. Death. When a tree dies it is no longer bothered by vines.
2. Fire. If you are a lucky tree, a passing fire may fry your vines but spare you. Even so, many vines can resprout from their bases, Smilax being a prominent example.
2. Bark that flakes off or sheds frequently, such as Gumbo Limbo, or Slash Pine. That’s a big help with vines that climb by clinging to bark, such as Poison Ivy or Virginia Creeper, less help with twining or scandent species such as Air-Potato or Cat’s Claw. Vines with tendrils, such as Grapes and Smilax, can defeat shedding bark by getting a “toehold” on branches or on neighboring trees and then spread all over, sometimes in great masses climbing their own older stems.
3. Shedding of low branches, and of old palm petiole bases. Dropping branches is not likely to help much in preventing vines altogether, but may reduce their volume.
4. Symbiosis. There are cases of useful ants snipping vines from trees.
NOW HERE WE ARE. NONE OF THE ABOVE IS ENOUGH TO ANSWER TODAY’S BIG QUESTION. THEREFORE WE HAVE NO CHOICE BUT TO VENTURE BRAVELY INTO THE SPECULATION ZONE. LET US GUESS:
If birds rain multiple species of vine seeds at the base of a tree, what might prevent those seeds from spawning an invasion of the trunk?
A. One partial answer is that life is tough for all young things (except rats) to establish, so maybe those baby vines often succumb to fire, to herbivores big and small, to flooding or drying, to competition from non-vine species, and to the many perils that allow only one seed in a zillion to mature.
B. Underground competition. Baby vines at the tree base need to compete with the massive established root systems of host the tree and its mycorrhizae. Additionally, most forest tree bases are sheathed with moss. Vines don’t seem to like that.
Hmmmm…moss vs. baby Virginia Creeper.
C. Shade. Tree bases are shady. Although variably shade-tolerant, vines do ultimately need light. A sign that shade matters is that you see more vines on dead trees than on living ones, and more vines on trees out in the open. I think shade is important.
D. Chemical warfare. You have “allelopathy” when one plant poisons competitors. I am aware of no studies testing trees poisoning vines, but why not? Those little baby vines are positioned directly where stemwash and fallen bark collect.
D. Basic life history. A big fundamental difference between trees and climbing vines is their plumbing. In relation to stem diameter, vines move vastly more water upward than trees. Fire hose vs. waterpik. For a rapidly climbing vine spreading hither and thither, making flowers, feeding berries to birds, taking over a tree, it must be great to have a high-volume pipeline in that skinny vine stem. But when the vine is young is that greedy tendency a liability? Maybe the immature roots, competing with the tree, can’t satisfy the demanding stem pipes.
E. Carbon dioxide? Temperature? Disturbance? Here is the actual major mystery for today. It is that climbing vines are increasing in prevalence around the tropical world. We can guess but nobody knows what was keeping them in check, and now isn’t. If we automatically say, “climate change,” we’re still left with the question of why that would favor vines over trees. There is one possible answer to that we already know—that special big-pipe plumbing. Without getting into boring details, vines store water and other resources better than trees, and also can repair drought damage. They tolerate drought and disturbance. Could the explanation be as simple as increasing drought and disturbance?
That was fun. If you have any new ideas of your own, chime in! I’ll tell the editors of “Unsolved Problems in Ecology” they can omit the vine chapter in the next edition.
*Dobson, A., R. Holt, D. Tilman. 2020. Unsolved Problems in Ecology. Princeton University Press.
Chapter: Muller-Landau, S. Pacala. What determines the abundance of lianas and vines. P 239-264.
**I’m using the term “vine” for any of what we think of locally as climbers, most of them woody: Air Potato (not native), Cats Claw, Cissus, Coinvine (can be a climbing vine), Old World Climbing Fern (not native), Grapes, Peppervine, Poison Ivy, Smilax, Snowberry (can be a climbing vine), Trumpet-Creeper, Virginia Creeper
Bald Cypress has to be one of the most beautiful and fascinating trees in Florida, in many ways. Thanks to sprawl, drainage, harvesting, hurricanes, and who knows what, you don’t see many large examples in eastern Palm Beach County. But there are a few, and a surprising little “micro-forest” is hidden in the bosom of Jupiter along Jones Creek just west of Jupiter High School.
The Bald Cypresses are the gray-colored treetops to the right of the swimming pool. A postage stamp urban habitat remnant. The darker area between the cypress and the orange rooftops is mangrove swamp.
The swampy nature of the habitat may be why the magnificent bald cypress and their associates are still there. The associates include pileated woodpeckers today, and two barred owls on the previous visit. Also notable, although all hard to find: Golden-Clubs (Orontium) and Jack in the Pulpit (Arisaema)
OK, how old are the Bald Cypress? Tough to figure, too many variables, and no way to measure precisely noninvasively.
The “cable” on the trunk is Coinvine (Dalbergia).
Disclaimer: my estimate is rough. UF biologists Katherine Ewel and William Mitsch estimated wild Bald Cypress diameter (not radius) to increase 1-3.3 mm per year. Let’s go arbitrarily with 2.5 mm per year.
Bald Cypress growth rings, by John St. John. Although tree rings generally represent years, that is not strictly so in Bald Cypress where water levels influence ring formation.
Today I measured the diameter of one jumbo trunk at 1200 mm, about 5 feet above the dilated base. That gives approximately 500 years, give or take a wide margin of error, but you get the idea. What was going on in the year 1524? By coincidence, I happen to know an answer. Last week I visited the Museo Nacional de Antropología in Mexico City and learned about Aztecs in the 1500s. The BC trees in Jupiter were young at the time of the nasty Aztec Conquest. Boggles my mind to know that today’s diehard urban Cypresses predate DeSoto and the Fountain of Youth. Seems that immortal Bald Cypress does not need a Fountain of Youth. The site then probably looked much as it looks now, just a whole lot bigger. Hope it is still there in 500 more years.
Aren’t the knees supposed to sit down in the mud and water? Knee-ish things sprout on massive horizontal branches. Rats—at first,from a distance I thought that might be an owl.
*There is a trail, and a short boardwalk connecting the parking lot just N of the Aquatic Center with the Cypress, but you may not want to go there. The site is tiny, and like most urban woods, there are human-related occurrences ranging from “unaesthetic,” to questionable people in the shadows. Don’t go there alone, and be aware that the entire visit will take under 20 minutes.
Several years ago I made a “Winogradsky Column” for my classroom, a tall glass vase filled with wet mud to study wetland soil bacterial growth. To my amazement the top half filled suddenly with a million thin strands resembling a plate of vermicelli, or an oversized fungus, or icky dead nematodes.
Pre-Bladderworts (the thin threads, not the thicker stems)
At first, the tangled strands were a mystery, but they soon morphed into Utricularia subulata complete with its teensie traps. Then it happened again. This spring I filled a Tupperware with wet marsh soil to grow Harper’s Beaksedge for a project. Got more than bargained for: first spaghetti, then beautiful sunshine flowers on delicate stalks rising from the mud.
That plant has supreme reproductive power! How does it do that? Sure, seeds probably help, although a lot of utricularias are self-fertilizing, some, including U. subulata, have self-fertilizing flowers that make clonal fake seeds without opening. Even more useful when colonizing fresh marsh mud, utricularias can grow from fragments.
ZZBW on the march in the marsh! Are there enough pollinators for all!? Photo by ‘Soggy-Foot’ John Bradford.
Although the relative importance of this compared with seeds is unknown. Now I’m guessing for high relative importance: it seems the ZZBW can spring forth with astounding abundance and vigor to colonize marshes and Dollartree containers. My gut sez that’s from little pieces, and some other utricularias have pre-formed fragments called “turions.”)
Not only can it take over a marsh, the Napoleonic little Utricularia can take over whole continents. It thrives from New South Wales to Rio de Janeiro To extend the guess to cross oceans—birds carrying my imaginary microfrags (or seeds, or clonal pseudoseeds) from land to land and from pond to mudpuddle. To test the fragment notion, I’m going to put some pieces on wet filter paper, and on moist boiled sterilized soil. That’ll showya!
In the meantime, in 5 centuries of organized botany, a plant around the world can get discovered here, and discovered there, and discovered again some more. How’s a 19th century botanist in Lisbon to know a species discovered there was the same as one described separately in Albany? I counted (an incomplete list) of 24 different names for the same species. How did they ever do it before the Internet?
Xyrises are a big group, about 300 species, approximately 25 in Florida. The local species live mostly in sunny open wetlands. But an outlier, Carolina Yelloweyed-Grass, thrives relatively “high and dry” in open slash pine savannas and similar places.
Tagalong on the Xyris
The eccentric habitat is merely one unusual feature of a species with n oddball history, starting on or near an 18th Century rice plantation way down upon the the Santee River in South Carolina. To this day, it is unclear exactly what species actually was “the first” Xyris caroliniana, as no original material exists. That original “X. caroliniana” was probably not actually the species now officially designated to carry the name. Xyris caroliniana may be the “President George Bush” of the plant world. Serial use of one name is ok with presidents, but a bummer in botany.
Hard to generalize about 300 species, but most Xyris species have broad flat thickened leaves fanlike meeting edge-to-edge. Think of an Iris. Their main ecological challenge for those aquatic xyrises may be excessive sun while aerating oxygen-starved submerged roots.
Xyris smalliana in flooded marsh
It is different up in the pine savanna where Xyris caroliniana grows. Its problems include surviving fires. Xyris caroliniana consequently has a safe underground bulb from which skinny grasslike leaves rise in a three-row spiral. That the leaves and flower stalk are twisted probably reflects their spiral origins, and the twists may help the foliage compete with thick crowded grass.
Closeup flower photos today by John Bradford.
Speaking of unusual attributes: the flower color. With exceptions, xyrises generally blossom yellow. Xyris caroliniana differs by having white flowers and yellow ones on separate individuals. In the northern part of its range, yellow dominates, whereas in South Florida white rules, but yellow occurs too, even occasionally alongside white.
White (left) and yellow together
Despite the presence of both, it seems (with inadequate data) that on large regional scale and in a small meadow, either way, the two colors cluster, not at all evenly intermixed. This uneven clustering probably does not have much to do with pollinator distributions. Fact is, limited study shows much-to-most reproduction to be by clonal seeds produced by the plants sans pollination. The seeds are genetic replicas of the parent. That could explain the patterning, a white-flowered pioneer peppers its neighborhood with clonal white-flower seeds, these growing up to add more and more white-flower plants, and there’ya have it, a white-flowered cluster. Ditto for yellow in its own corner You’d wind up with “white zone” and “yellow zones,” plus here and there limited mixing.
Acrostichum danaeifolium (acros= tip, stichum = row, referring to rows of spore cases I guess. Danae was a mythological Greek princess and mother of Perseus. A plant genus, Danae, honors her, so I’ll take a guess that “danaeifolium” reflects similarity of the fern leaves to those of Danae.)
Pteridaceae, Maidenhair Fern Family
Distributed from Jacksonville to Brazil, Giant Leather Fern is one of only two (or three) Leather Ferns in the world. (The similar Acrostichum aureum has one known occurrence in PB County.) Not only is Acrostichum widespread in space, but also in time, dating back at least into the Cretaceous Period. This fossil from Spain (discovery and photo by Rafael Moreno-Dominguez) doesn’t look much different from this current specimen (discovery and photo by John Bradford).
An oddity of Leather Fern was noted by plant ecologist Dan Janzen some time ago who raised the question, “why don’t mangrove forests have a more diverse understory than just Leather Ferns?” (He had no answer.)
By JB
A simple-minded partial answer that would not have impressed Dr. Janzen, as I see it, is what habitat on Earth could be worse than the mud under mangroves? Salty! Deeply shaded! Oxygen-starved! Tides! Moving sand and mud! Crabs grazing! Microbes and algae! It is a truism in Ecology that horrid habitats make for low species counts. But the survivors have a monopoly. And Leather Ferns do a good job of owning the habitat. In the photo below you can see some competitors trying to establish below Leather Fern along brackish Jones Creek in Jupiter. No doubt those upstarts are doomed, if salty tidal water doesn’t pickle and smother them, fern-shade will.
It must be rough for seeds to establish in mangrove mud, but Leather Fern has a huge advantage by not having seeds. Its millions of dustlike spores “blow all over the place,” including dead branches, hummocks, and raised spots where conditions are less harsh, facilitating establishment. Oddly, the tiny reproductive individuals that hatch from the spores can go through their sexual cycle in a matter of weeks rapidly before “trouble can strike,” and they change from starting out unisexual, to becoming bisexual and apparently able to fertilize themselves as plan-B. To be even more certain of standing its ground, the fern buds clonal babies off its rhizomes running through the mud.
Oh phooey…here comes Hurricane Season. My old island home Barbados is about to get a swirly. In Barbados, in Florida, and around the world, how can hurricane-“grass” withstand a hurricane, not to mention all the other tortures this weirdly immortal sedge survives? Answer (I think): it is one of those wonderful plants that alters its environment to its own benefit. The fancy term is “autogenic habitat modification.” You might call it positive feedback. If a beaver builds a lodge or paper wasps build a paper home, that’s autogenic modification but no big deal—creatures have intelligence and agency. But DIY “homes” for plants are pretty nifty. Sure, any dumb ol’ tree may funnel water and debris to its base, or saw palmetto may shade out competitors, but some cases of “make your own space” are more wondrous.
Hurricane-grass may weather a twister, or thrive on lava (they do), or occupy asphalt, or dominate bare scrub sand where nothing else lives because, like other post-apocalyptic survivors, they have a bunker. We sort of.
Wreath
If you’re truckin’ along and spot a Hurricane-Grass it often looks like a green wreath dropped on top of the ground, a raised ring of little green rosettes, and a black or sandy unoccupied center. Seen from above It grows outward, like a fairy ring in the lawn, leaving the enlarging hollow center behind. Viewed from the side (lie on your belly with chin to the ground – ha ha), it looks like a tiny sand dune two inches tall having green leafy rosettes on the surface.
But here’s the thing, or things. Thing 1: Each of those rosettes on top is merely the tip of the whole plant. The rosette on a trunk just like the tuft of leaves on top of a palm is on the palm’s trunk. If you pull the Hurricane-grass out of the sand it actually resembles a little palm, its sand-covered “trunk” looking at first glance like a taproot. But brush off the sand and look closely: the “taproot” is actually a stem covered with old leaf bases, like the “boots” on a cabbage palm. The weird part is that all those “trunks” are embedded in the sandy bunker. They are “buried” aboveground in congested groups. Think of a dense stand of palm trees up to its leaves in a raised sand dune. Those little stems are as protected as can be, and even better, their growing tips are not even at the exposed top, but are sunken down in the mini-dune bunker. How does the colony build up that protective sandy dunelet? Seems like sand drifting in wind (or water) catches on the exposed portions, settles, and piles up as the rosette then rises a little taller to stay exposed.
Chin on the sand view
Helpful diagram of the same view. Note the mini-sand-dune, the rosettes at the top of the sand, and the branching.
Exposed! Stem (brown, superficially resembling taproot) to front and right)
Growing tip hidden safely below exposed top.
Thing 2: How does the wreath expand? Those buried stems become increasingly crowded by branching in a Y-shaped pattern, the dead zone in the broad hole-in-the-donut probably a good water-catcher.
How many ways does the sand protect the sedge and its hidden growing tips? Who knows? Undoubtedly from sun, UV, wind, drying, abrasion, bugs, hungry hippos, unfavorable surface soils, and in its typically hellishly hot haunts, from heat. Just for fun I monitored hurricane-grass temperatures from yesterday afternoon through the night and all day today. Readings were recorded every minute for approx.1700 minutes in three positions:
Position 1. Nestled down among the hidden stems 1.5 inches below the rosettes. (Green line)
Position 2. Buried in the nearby soil 1.5 inches deep. (Brown line)
Position 3. On the exposed soil surface. (Orange line)
Tracking the heat for one afternoon, night, and following day. Orange = surface temperature. Green = temperature between stems 1.5 inch below rosette. Brown = buried in soil 1.5 inch.
The protection from the soil-surface temperature (orange line) was substantial, in the daytime sun cooler and more stable. The temperatures among the stems (green line) were roughly equivalent to burial in the nearby soil (brown line), although actually a little cooler. Notice that at the highest temperature you see the biggest difference between the green and brown lines. Betcha that gap broadens at even-higher temperatures.
Darwinian competition is rough business: frogs eat flies, snakes eat frogs, hawks et snakes, and Love Vine eats other vines in the scrub. In case you don’t know Love Vine (Cassytha filiformis), it is that yellowish spaghetti vine festooned all over other plants in scrub and additional habitats. It forms massive tangles smothering and parasitizing all beneath.
Love vine bothering its neighbors, by John Bradford
Love Vine penetrates its plant victims with little suckers called “haustoria” and sucks out sugar and water.
Haustoria at work, JB
Not nice, but it gets ahead in the world. Love Vine probably came here all the way from Australia, pollinating itself to make the intercontinental hopscotch easier. Tiny thrips, insects that parasitize the Love Vine, ride in a stowaway space between the fruit wall and an outer covering of fleshy birdfood. Apparently the birds help the vine AND the thrips get around. All well and good, but what interested me today is seeing in the scrub that a different vine, Earleaf Greenbrier (Smilax auriculata), not only seems immune from the Love Vine, but also uses it to rise above the tangle into the sun. The invulnerable Smilax climbs up the Love Vine unmolested, and snakes along the top of the Love Vine to enjoy an easy path above all the shade, crowding, and parasitism below.
Smilax ignoring Love Vine. Can’t catch me!
It gets a little more complex. Another vine in the scrub (and elsewhere) is Muscadine Grape (Vitis rotundifolia). The grape resembles Smilax in overall habit, stem diameter (when in scrub), climbing ability, leaf size, small plain clustered unisexual flowers, and making “bunches of grapes.” Unlike Smilax, however, the grapevine falls prey to Love Vine.
Above: Grape is not immune!
Smilax comes out on top
Why the difference? Most woody plants have their water-conducting and sugary-sap poorly protected just under the bark. Easy pickings for creepy Love Vine. But Smilax is different: its stem is built like cables within cables. (Because It is a monocot if that matters to anyone.) If you cut across the stem and look end-on, the plumbing is deep within the stem and surrounded by a hard protective sheath. No parasite is going to break into that!
End view of Smilax stem magnified. The green circles surround the sugar pipes. The big blue rings circle the protective sheath. The large open ends within the sheaths are water pipes.
Don’t get me wrong. No suggestion here that the Smilax stem internal structure is a special adaptation to block Love Vine specifically (although it might have a lot to do with protection in a broad general sense). So do those thorns. Think of it as a chance thing…lucky Smilax winds up in a habitat with a stem structurethat just happens to offer an advantage against would-be competitors such as grape, or maybe species long-gone because of not having the “right stuff.”
Treasure Coast Natives 