Treasure Coast Natives

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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.

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*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

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Taxodium distichum

Re-re-revisited

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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.

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*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.

(revisited)

Utricularia subulata

Lentibulariaceae

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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 19^th 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?

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Xyris caroliniana

Xyridaceae (The Xyris Family,  not real grasses.)

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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 18^th 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

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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.

Meanwhile back in the Cretaceous

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Fimbristylis cymosa (fim-BRIST-ah-lis sigh-MOSE-ah)

Cyperaceae, the sedge family

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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.  

(are miniature hoses)

Obviousness should not always “go without saying.”  In nature, obvious everyday experiences have plenty of beauty and wonder, and can sometimes prompt new explorations.   There’s no “eureka” in observing that rainwater trickles to the bases of plants.  Yet  it’s fun to go out after a rainshower and see where the drops drip. Plants are giant funnels.

Direct water capture is critical to some species, such as tank plant epiphytes.

Photo by John Bradford

But what’s arguably more fascinating are the more “iffy” cases.   Is there a correlation between dry habitats and plant funnel-ness?   Haven’t “done the math,” but, probably:   think Yucca in Yucatan. In other species, funnel abilities might be a mere advantage,  or sometimes the opposite. 

By JB

Many plants have “winged stems”:   blackroot, crownbeard,  winged elm, and many more. These often have “winged” or “alata” in their names.   Do the wings help channel water?  

Winged stem on crownbeard. By JB

I wonder if the corky wing in Corkystem Passionvine might absorb water into the climbing stem without recycling all the way down to the roots.   Or if the spongy bark on Peelbark St. Johnswort helps with water storage and evaporative cooling.  Ants love that species;  maybe soggy bark is why.

Coincidental association of tree and small plants at its feet, or nurse tree in action?

Nurse trees aid smaller plants around their bases.  Lots of ways a big plant may benefit a little pal, including funneling water to its base.  Vines climbing a tree may have a double plus:  a free ride up into the sun, and free water running down the host tree to the spot where both are rooted.

Ever notice how fire ant nests center around large grass clumps?   Betcha rain collection at the grass base helps wet their whistle.  And speaking of “grass,” a clump of hurricane-“grass” has lots of little sedge funnels around a big spongy tussock.    Does the “sponge” store and distribute the captured water? 

Plants in your ants.

Bald Cypress grows mostly in swamps comfortably free of water deficiency.    Its close relative Pond Cypress, by contrast, often occupies open places prone to seasonal drying.  Do its upright twigs and upright leaves help with seasonal water needs?

Big flat fluted semi-upright cabbage palm and saw palmetto leaves, in addition to being sun-catchers, sure look like water catchers.  Somebody should measure stemflow down a cabbage palm trunk.   All those vines, mosses, and ferns on the trunk love it.

Who knows.  Very little about external water dynamics has received formal study.  That just means “more freedom” to wander, wonder, speculate, and discover.  

C4 Yourself!

Euploca polyphylla (aka Heliotropium polyphyllum)

Boraginaceae, the heliotrope family

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Ever wonder how some species flourish, bloom, and prosper at ground level in the hottest, most sun-parched habitats.   I accidentally dropped a digital temperature-recorder in a dry marsh the other hellishly sunny day, and it maxed out flatlined  at  115 degrees F before I recovered it.   Who knows how much higher the actual reading should have been?   Think of walking barefoot across hot asphalt on a bright hot day.   That’s why there are no plants in Hell.   Maybe it is counterintuitive that it often tends to be (a lot) hotter on the ground than above it.    A burnin’ ring-o-fire at  ground level can raise fun questions:

All photos today by John Bradford. This is how the PH looks this morning.

Do the broad lower leaves under a saw palmetto or the skirt of dead foliage under a Golden Aster heat-shield the more-delicate tops?    How important is evaporative cooling on the down low?   Why do some plants have rosettes during the cool season and move their leaves up the stem in the heat?   Does it help dry marsh plants have a “mulch” of spongy periphyton persist from the wet season?   Does leaf litter protect shallow roots?  Why do sedges often cluster leaves at the top of the plant?  Why do low Myrtle Oaks in scrub have a bewildering array of leaf forms, sizes, and textures?  And so forth.  A fun theme for a walk with one of those point and shoot “covid” no-touch thermometers.

Let’s get to the point via one final question.  How do the species that actually love the hotfoot soil get away with it?   Yes, some have extreme adaptations, like Cacti.   Some dodge hot times or actual fire & flood using seeds, or deep roots, or shape-shifts.    Harsh habitats are good opportunities for species able to tolerate them, because harshness suppresses competition, and pestilence may be tamped down too.   In a “nice shaded moist” rainforest you’re competing with a zillion close neighbors.   By contrast, in the desert or Florida scrub there’s plenty of real estate,  if the harsh physical conditions don’t thwart you.   The late British ecologist J.P. Grime divided basic plant  lifestyles into a triangle:  competitors, ruderals (weedy fly-by-nights), and stress-tolerators.   (Hey, that’s kinda like office politics.)  

This all leads to the fact that being a stress tolerator can open doors.   Especially in “new” environments with changing climates, such as the passage of an ice age.   A local stress tolerator is the beautiful Pineland Heliotrope.   It stands up to ground-level cookery even without obvious protections.

Biologist Michael  Frohlich and about 19 collaborators nailed that mystery with molecular research.   Pineland Heliotrope’s secret weapon is a superpower called C4 photosynthesis, best known in grasses, which live at ground level.   C4 allows comfort and joy in places too hot and dry for many competitors.   What’s interesting about this ability in heliotropes is that only some have it.   As the Frolich team uncovered, there’s a cluster of about 18 species (in the genus Euploca)  that  evolved and diversified rapidly in hot exposed American habitats thanks to an ancestor bestowing upon them the C4 ticket to invulnerability. So they prosper in the exclusive stress-tolerator corner of Grime’s triangle.    How cool is that?

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To dig in deeper:

https://academic.oup.com/botlinnean/article/199/2/497/6510913

Centella asiatica

Apiaceae (Carrot Family)

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In the great big plant world, 250,000 flowering species, only a handful are known to be pollinated by ants.   Let’s guess:  ten species, probably too high.  That’s 0.00004 percent.  Do we have one of them here in PB County?   Maybe, maybe not.

Centella asiatica, sometimes called Pennywort, and sometimes called Gatu Kola, is an odd little wonder.   [Oops, that should be Gotu, see reader comment below.] It grows all around the tropical world, including around here in wet marshy places, although it tolerates seasonal drying.   It is one of those bioactive plants with a million historical and current medicinal and cosmetic uses, in many cultures.   (Careful,  there are toxins.) I’ve never been much interested in “medicinal plants,” so if that’s your interest, there are 100 websites with info on this species.   

How has a small creeping plant crept all over the hot-climate world?   Part of the answer is fragments.   If you take marsh soil and put it in a container nice and wet, up pop lots of baby Centellas.  A whole lot of them.   I don’t think that is from “seeds,” but rather rhizome pieces.  The reasons I don’t like “seeds” is that the flowers and fruits are rare.  I have the species growing at my home, and the babies are coming from tiny unplanted plant pieces.  That ability alone is mysterious.  How can the mud be full of ANYTHING that spawns baby Centellas every few inches?  Maybe it is magic.

To dig in deeper, the floral biology has been studied a little.  Biologist Asma Javaid and collaborators looked into it:   in pots, in  a garden, in Jammu, India.   (How does that relate to a Florida marsh?)    They found the plant to be largely self-pollinated. That I believe.  They also concluded ants are the insect pollinators to the limited extent there are insect pollinators.   But that sets off alarms:

1. See above. Ants pollination is EXTREMELY rare.

2. The results were based on potted plants in a garden.

3. Did the ants merely get on the flowers uselessly or worse, or did they actually pollinate?   In the Jammu study, flowers covered with bags produced more seeds than those open to pollination.  Maybe the ants visited the flowers in a bad way, stealing pollen or otherwise deleterious, and the bags protected the flowers from the ants?

The flowers are minute, not even ¼ inch in diameter,  held near ground level under foliage, maybe an inch in the air,  when you can find them which is not easy.   Find the flower in the photo below. (They are dead-center.)  

Find the flower

But being low does not necessarily = ants.   There are little flying insects, not to mention that pervasive self-pollination.   Today I sat on the soil in the Pine Glades Natural Area all soggy-assed for 24 minutes watching the Centella flowers to see if anything visited. Naw!  But who knows what 24 hours watching might discover.    Wherever and whenever the species originated (tropical Asia?), I’m sure Florida is distant in time and space  from the original pollination context.

So all in all, nobody knows the Florida Centella story.  Self-pollination is surely substantial.  So is super-sprouting from fragments, no doubt.  

I suspect that marsh animals, such as marsh ricerats,  help spread the fragments as they scurry around the marsh on their criss-crossing trails, which can channel flowing water able to relocate plant bits over long distances.   And that’s where it stands with Gatu Kola.   Does anything visit those tiny hidden lilac flowers here?  I’ll place a wager…not ants.

Animal (ricerat?) trail in Centella habitat marsh