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Elephant’s Foot and the Green Treasurechest

Elephantopus elatus

(Translated: Tall Elephant Foot)

Asteraceae, the Aster Family

Among the local wildflowers, Elephant’s Foot is a standout… pretty, weird, and abloom all over Halpatioke Park this morning where John and I pursued a photo project.

Elephantopus elatus 1

Elephant’s Foot with its rosette, photos by John Bradford.

Preferring open dry habitats, its leafy rosettes rest flat upon the earth.   A vertical stalk rises a foot or two, often branching as a perfect Y,  and tipped with three equal bracts embracing a dense bushy-bristly flower head.  The spongy base of the head protects young flowers and fruits, and probably holds moisture funneled inward by those bracts.  Having just a few flowers exposed at any given time allows the reproductive cycle to span weeks accommodating pollinators of every buggy sort.

Elephantopus elatus 3

Most of the foliage sprawls radially on the ground atop a perennial taproot.  Rosettes are common in the Aster Family, and in plants of harsh open environments.   There are multiple advantages to rosettes in such places, including minimal wind exposure, using the ground to support the leaves,  safety beneath most grazers and fires, easy regrowth straight from the root,  and extra water collection.

Members of the Aster Family tend to have a biting pungence, some might find unpleasant while others may approve, Marigolds for example.  Asters are the primary although not sole sources of defensive compounds called lactone sesquiterpenes, which are bioactive as you might expect chemical defenses to be.

Normally I’m skeptically unenthusiastic about the countless historical uses of most plants.  Google a widespread species and see how many ailments it has treated.   Thousands of plants have been screened for antimicrobial activity, and no surprise, many do kill cooties.    Most plants have chemical defenses. (Please do not eat the weeds.)

Elephantopus elatus 2

But there is chasm between historical remedies and modern clinical efficacy.  Today we may witness a potential bridge across that divide.

Lactone sesquiterpenes have attracted attention for anti-cancer activity, and the positive indicators extend promisingly past vague traditional treatments all the way to specific understanding of the biochemical mechanisms by which these chemicals cause programmed cell death (apoptosis), including roles in gene control.   Elephantopus species are players in this realm.

Elephantopus species produce lactone sesquiterpenes, some named for today’s plants: elephantin,  elephantopin,  and others.   These have hit the cancer literature as understood in mechanism, effective in the lab, and worthy of a deeper testing.

This is all promising hand-in-hand with the march of biotechnology, and lactone sesquiterpenes or derivatives from some relatives of Elephantopus have made it to clinical trials, including products from Mulleins, Feverfews, Wormwoods.  All in the Aster Family.

Exciting stuff, and maybe the beginning of the future predicted emphatically by the leading botanist of my generation, Dr. Peter Raven, who was 1999 Time Magazine Hero of the Planet with the message of saving the rainforest as a green treasurechest waiting pharmacological discovery.     Emerging biotechnology of today and tomorrow is the likely  key to that treasure, and maybe some of the gems are behind the soccer field in Halpatioke Park, Stuart, Florida.

elephantopus elatus head

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A start for those who want to dig deeper:  DIG HERE

 

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Posted by on September 22, 2017 in Uncategorized

 

Hurricane-Induced Cladoptosis Spreads Across Florida Woodlands

At the suggestion of Virginia nature friend Pat Bowman, how about wild plants and hurricanes. Do the wild plants care?

Some relocate.  It seems that during Hurricane Wilma in 2005, a tropical weedy grass. Steinchisma laxum, previously unknown in North America invaded South Florida Florida arrival was overdue, an easy breezy hurricane hop from the Caribbean, assuming the hurricane did it.   Blog co-conspirator John Bradford standing in Halpatioke Park was the first soul in North America to say, “hey this does not fit the measurements of any grasses expected around here.”    Now you can hardly escape it.

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Steinchisma laxum is everywhere, perhaps thanks to Wilma.

My lawn today still has on it millions of small leafy twigs shed from Live Oaks.  It is obvious to reckon, “well the gusts blew those free.”  True,  and  branches whipping wildly knocked them off too.  But there’s more to it than immediate physical damage.    That something more is cladoptosis, defined as “planned” twigdrop.   It happens in certain trees, notably in Oaks.

Earlier research indicates the tree somehow “decides” which twigs shall live and which shall shed.    Determination occurs early in the life of the twig.  Those fated to shed follow an odd development:  the “veins” connecting them to their parent branch narrow and choke off supply.   It looks like a ring of decay girdles the twig at the snap-off point, and the bark appears to pinch in.   When the twig separates, the severed base is not fractured and splintered, but rather more of a rounded knob, like your femur joining your pelvis, essentially “designed” to drop free smoothly.

cladoptosis 2

Irma-severed end of Live Oak twig.  Unplugged cleanly, not torn, splintered, or fractured.

Why?  The limited literature indicates a hormonal seasonal reaction abetted by stress.  In short, those scattered twiglets were poised to come loose before Irma roared in.   The storm merely shortened the timeframe to hours instead of weeks or months.   The tree conceivably needs all its leaves during the moist growing season, but can’t support the full canopy as the warm wet season winds down and dry times approach.   The hormone ethylene is implicated.   The same hormone serves commercially to defoliate crops for easy harvest.  The twigdrop helps storm-proof the tree by reducing wind drag.  How many wind storms does a 500-year-old Live Oak experience?

Although Slash Pines may fracture or topple, another common probability is shedding, not little twigs, but rather large dead branches low on the trunk.  Ever notice how those trees have nice green canopies up high but not many dead branches down low?    There’s a perception that the branch-shedding is protection from ground fires, and that maybe those old branches even have some basal weakness to set them free.   “Cladoptosis” of large branches?   Maybe…more research needed.  The break-off is not clean, uniform, and mechanical as the Oak twigs.   Walking in The Haney Creek Natural Area today John and I saw the broken pine branches to be all sizes, alive, and dead, and torn and splintered.   Less  convincingly “preplanned” than Oak twiggies.

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Pine branch shedding uneven, messy, and fractured.

Many woodland trees lie prostrate from past thunderstorms and hurricanes.   My favorites are in swamps:  Red Maples and Sweetbay Magnolias where the fallen tree resurrects multiplied as branches rise vertically to become new trunks.  Ex uno plures!  From one comes many, a whole new mini-population.

Busted-off branch bases and torn bark on standing tree trunks invite trouble and may or may not heal.    Healing comes mostly from above, which is why branch-stumps tend to fare poorly…”above” is gone.    Sugars, hormones, and growth processes cover a wound mostly downward, like pulling down a window shade.

After pruning, grazing, or hurricanes new stems grow from the lateral buds situated where the leaf joins a skinny young twig.   Repeat, skinny young twig.   But on any tree damaged in a storm  a few years ago new branches sprout from the thick old trunk.   How can that be, that gnarly old trunk lost its lateral buds decades ago.   Well, not entirely, that old bark has an amazing emergency repair mechanism known as latent buds.  Latent buds creep outward hidden within the bark as the tree expands, waiting for hurricane day.  The equivalent of me sprouting a new leg should one be yanked off.

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Latent buds in bark competing to replace severed stem on Strangler Fig.

The magical regenerative powers of plants go doubly in an environment where storms and fires are endemic, such as here.  Check a wild area after a major storm, and there is likely less damage than expected, in some places no damage is even detectable.  That was almost true in Haney Creek today, Liatris all abloom, Hog Plums with plums still attached, and most foliage intact and green.  The native flora evolved to stand up to trouble.   And where destruction does occur, the ability of life to rise from subterranean structures or from broken plants is quick.    Moreover, the soil seed bank is ready to rise.   Disturbed dirt never stays bare for long.

If you want to find damage, seek it near the sea.  The salty winds “burn” foliage, and sow salt into the soggy earth.   The plants mostly recover ok from the saline attack.   Guess what species is especially resistant.  Live Oak.

Does a big hurricane change the composition of the flora?  Sure, within the constant ebb and flow of species in our dynamic world, but, given the fact that our flora has evolved through thousands of hurricanes, one event won’t cause radical mischief, except maybe where human activity has created an unnatural imbalance.

Upon emerging from our bunkers the morning the tempest subsided, one of the most positive sights after, “hey, we still have a fence,” were blue jays and butterflies.  Where did those jays ride out the fury, and a butterfly in a hurricane, well, that’s just poetic.

 
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Posted by on September 15, 2017 in Uncategorized

 

A Grass, a Fungus, and a Virus Walk Into a Bar…

What a dumb time to write a South Florida blog, as we all wait for Hurricane Irma to blow in some new weed species.   After the house is as ready as possible,  there’s not much to do other than hang around and fret.   So, here’s something to read before the power blinks out.   Today’s core topic came from my second favorite thing after vanilla cream donuts, “This Week in Virology” by Professor Vincent Racaniello who makes all things viral fascinating.

Can a virus be good?  Yes, occasionally, and probably far more often than we know.  Today we shall see a native grass species (if you stretch the taxonomy) and its associated fungus meet a helpful virus.

Dichanthelium,  the Witch Grasses, comprise roughly 80 species,  numbering about a dozen in our usual neck of the woods.   Pretty, often petite, sometimes forming rosettes.

D. chamaelonche 2

Dichanthelium chamaelonche.  All photos by John Bradford.

Today is all about a super-powered grass formerly classified as belonging to our local D. acuminatum.

D. acuminatum - specimen 4

D. acuminatum

Dichantheliums are notoriously tough to classify.  In any case the variants of interest are not known in Florida, but rather at scattered hot springs over a large area of western North America.    A recent and credible classification  interprets the hot-springs-inhabiting populations as a species in its own right, D. thermale.    A grass at home in hot water?    Really hot.

Recently studied in Yellowstone Park the witch powers of Witch Grass are proven where it bubbles bubbles toils and troubles in natural cauldrons as steamy as 65 degrees C (149 degrees Fahrenheit).  For comparison,  hot tap water is typically around 50 degrees C (122 degrees F).

The super-grass hosts a symbiotic fungus called Curvularia protuberata, at first glance a suspect responsible for the empowerment.  But infecting the grass with the fungus doesn’t help.   UNLESS a third player is tossed into the brew, not eye of newt, but a newly discovered virus.    The virus plus the fungus jointly confer heat resistance on the grass.

A big problem with symbiosis is that the codependent species must have coordinated reproduction and dispersal.    Our hotfoot grass turns up in small isolated populations at hot springs sprinkled over hundreds of miles.   Do the Three Musketeers all travel together?    How?  One component is known…the virus moves generation to generation in the fungus within the fungal clonal spores.   Then do those virus-bearing spores ride along somehow in the grass’s seeds?  Unknown, but don’t they have to?  How did the three species hop from Yellowstone to northern California and far beyond?

There may be more similar  fungal-viral-grassy unions to discover, because our fungal genus Curvularia is large, often plant-pathogenic, and frequently consorting with grasses.   The same fungal species in the Witch Grass, Curvularia protuberata, is also a pathogen on rice, so who knows, maybe it helps the rice sometimes?   And if in rice, it must infect additional grasses.  Could the empowering fungus-virus duo help concoct super-powered rice?

DichantheliumerectifoliumJWTOct.[1]

The mechanisms of all this are poorly known so far, but researchers understand a few things.  When the virus infects the fungus, the fungus accumulates mannitol, a sugar-alcohol common in plant defense mechanisms, and also a human medicine, such as a laxative.   Does the viral infection put the fungus into a defensive mannitol-making posture, and then the grass exploits the fungal protective arsenal?  Probably much more complicated than that simplistic first notion.

The grass, fungus, and virus have drawn the active attention of researchers interested in heat tolerant crops.  That’s a big deal in a world where hot conditions limit crop options, and where climate change will boost the mercury.  Experiments have already created heat-tolerant tomatoes by infecting them with the Dichanthelium fungus-virus sidekicks.

D. strigosum

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Posted by on September 7, 2017 in Uncategorized

 

A Tale of Three Species

Where Did Our Locally Endemic Wetland Species Come From?

South Florida has extreme geologic history.    High dry habitats have been exposed above water for eons.    The opposite is today’s topic, wetlands.  Freshwater lowlands are South Florida trademarks.  Our present-day swamps, marshes, depression ponds, wet prairies, soggy pinewoods, and the Everglades hid beneath salty seas as recently as 15,000 years ago speaking very roughly, a teensie winky blink in evolutionary time.    If  their habitats were blue lagoons  until just yesterday, where did our wetland-loving plant species come from?

For species widespread beyond our region, duh, they migrated here from afar when conditions permitted.  But what about species limited to (endemic to) South Florida?  Yes, they could have shown up here from somewhere else and then disappeared there, but unlikely and arbitrarily rejected.  Ground rule—we will trust locally confined species to have originated locally.   Yes, it is all speculation.   We’re just having fun here.

pine glade sundown

Even though most of our present-day lowland areas were beneath saltwater, the exposed elevated uplands were not 100% dry.   Those raised islands must have had rain-fed depressions, ponds, and marshes where freshwater life could take refuge, freshwater Noah’s Arks ready to repopulate the vast lowlands when the salty seas subsided.

Even acknowledging spotty refuges, a massive new start defined soggy South Florida just a few millennia ago.   Huge upheaval, huge abrupt changes.    And that makes it fun to wonder how our locally endemic wetfoot species might have popped up.  Each of those species has to have an oddball story.   Odd circumstances generate odd histories.

Here are three as I see it:

 

Coleataenia abscissa (Panicum abscissum), Cutthroat Grass, and the Running Rhizomes

Cutthroat Grass may be an example of a localized “species” originating as a regional spin-off from a widespread northern species.  Cutthroat grass is so incompletely separated from its ancestral species,  its classification as a species is dubious.  Some taxonomists demote it from species status to a subspecies as Coleataenia longifolia subsp. abscissa, you might say a mere local variant of Coleataenia longifoia.

Coleataenia longifolia ranges across much of North America with additional spinoffs in other places.  Confusing?  Yes.  Species is a human concept…the plants do not read textbooks.  These grasses represent a big messy dynamic splintery complex where “species” are not defined crisply.

Even as a mere splinter group, Cutthroat Grass must have had some way of expanding its new brand while not merging back into its parental species.  Cutthroat Grass is aggressively rhizomatous.  South Florida is filled with rhizome-making plants able to colonize large areas clonally, thus spreading into what some botanists call “microspecies.”

This rhizome-ish microspecie-ish situation with Cutthroat Grass is reminiscent of another local wetland grass limited to Florida, Aristida rhizomophora, named for its prominent rhizomes.    It seems to be a wet foot Florida derivative of the generally more upland Aristida stricta which has no rhizome or just a little, especially in South Florida.   It looks like A. rhizomophora took that little ancestral rhizome and ran with it bigtime, spreading like Cutthroat Grass to become a microspecies or whatever you choose to call it.  The designation matters less than an understanding of what happened. (And I could be wrong.)

 

Polygala smallii,  Small’s Milkwort.   A Pollination Introvert?

A third local twig branched off from a widespread northern species is Small’s Milkwort.   DNA shows it to be a chip off of Candyroot, Polygala nana.  The two are a challenge to distinguish.  Because Small’s Milkwort is often encountered in upland habitats, it may be a stretch in today’s wetland context, but even in uplands it likes relatively moist depressions, and is a facultative (part-time) wetland species.    Also, its  parent species Candyroot prefers moisture.   The taste for uplands while retaining a love for moisture makes Small’s Milkwort a candidate for those refugia mentioned above.

Polygala nana 1

Candyroot, Polygala nana, by John Bradford

A subtle and overlapping difference in flower color helps distinguish the two, with Candyroot brighter yellow than Small’s Milkwort’s slightly-greenish yellow.

This yellow flower business echoes a second Milkwort pair.  The Florida endemic Polygala rugelii has bright yellow flowers.  The similar Polygala lutea favors orange. Thus we have two Polygala pairs, each with one member restricted to Florida and the other widespread and more northern, separated in part by the yellowness of the flowers.  Pollinator color preferences matter.

But then again maybe not always.   What forced Small’s Milkwort to cleave unto its mother Milkwort?   Geographic separation long ago is possible, remember those refugia, but there is a possible second isolation factor.   Small’s Milkwort reportedly appears to be self-pollinating.    That would prevent it from mixing genes with its parent species, thereby allowing a separate new “species”  to diverge.  If you want to keep bloodhounds and boxers separate, don’t let them interbreed.  Same with Polygalas.

Did the Small’s Milkwort flowers evolve from bright yellow to yellow-green because they don’t need to attract pollinators, and does their green tinge add photosynthetic ability?  Objection Your Honor!—that question has no evidentiary basis.  Question withdrawn.

 

Litrisa carnosa (Carphephorus carnosus), Pineland Chaffhead.  Not a Splinter, But a Merger

This case is weirder than the previous two.   If our Cutthroat Grass and Milkwort split off of raggedy bigger northern parent species and stopped interbreeding with them, Pineland Chaffhead is the other side of the coin, a merger.   It originated as a hybrid, reproductively a loner which somehow managed to spread.

Carphephorus carnosus 9

Pineland Chaffhead,  Litrisa carnosa, by John Bradford

Tennessee botanist Edward Schilling seems to have finally nailed this misfit.    The genus Carphephorus where Pineland Chaffhead resided turned out to be a bad genus in the sense that it did not represent a single branch on the tree of life, and had to be dismembered.    Pineland Chaffhead became reassigned to a genus of its own, Litrisa, presciently first proposed by John Kunkel Small two generations before Dr. Schilling’s DNA confirmation in 2011.  That’s the same Small as in Small’s Milkwort.  DNA revealed Pineland Chaffhead to be a probable hybrid bridging two different genera, Carphephorus as newly redefined, and Trilisa.

How might the hybrid Chaffhead have propagated and spread?  Many members of the Aster Family have asexual clonal seeds, with no data for the species in question.  One thing is clear, it makes babies in spades around its feet, removing any questions about its basic ability to go forth and multiply, somehow.

Carphephorus carnosus 8

Despite being an apparent hybrid, Pineland Chaffhead  makes plenty of babies, by John Bradford.

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Posted by on September 1, 2017 in Uncategorized, Wetland Species

 

Buttonweed (Shrubby Flase Buttonweed) (and the wasp and the cricket)

Spermacoce verticillata

(Spermacoce means seed-point, because the little dry fruits have four points.  Verticillata presumably refers to whorls (verticils) of  flowers and young leaves.)

Rubiaceae (Coffee Family)

Common plants interest me more than the rare species, because the common ones are everyday friends.   There’s so much to discover right under our noses.   Today’s plant is literally everyday in parking lots, asphalt cracks, roadside weeds, pastures, and lawns.     Spermacoce verticillata is an exotic invader from the Coffee Family as well as one of the most abundant and toughest weeds in South Florida.   If you live here and want to see it,  step out the door.  The plants can rise five feet tall, or lie low and spread into a patch where grazed or mowed.    On top of overall immortality, the plants re-root where they touch the ground, and the tiny seedlike fruit segments boast a 50 percent germination rate.  There’s no stopping it.

Spermacoce verticillata 1

Buttonweed on dismal soil.  It doesn’t care.  Today’s photos by John Bradford.

That is good news is you dislike mole crickets.    The holy grail of pest control is a natural approach using pests of the pests, although that has been known to backfire when the attackers spread to native relatives of the target enemies.

Evil pests of Florida lawn-lovers are invasive mole crickets, multiple species.    Their arch enemy is a parasitoid wasp Larra bicolor, introduced from South America, as is today’s weed, the wasp’s favorite nectar plant.    The wasp lays an egg on the mole cricket, where the resulting larva sucks life from its host, terminally.  All  natural cricket control!    Buttonweed is available commercially to foster the cricket-killing wasps.  In that context call it “Larra Flower” echoing the Latin name of the wasp, although somehow I don’t think market-driven neo-naming will stick any better than “Freedom Fries.”

Spermacoce verticillata 2

Here we have a case of cultivating one invasive exotic to feed another introduced exotic to encourage it to kill still another invader, an exotic ménage à trois.   All three species have native Florida relatives.  I have scant idea if that implies risk.  From a standpoint of general principles, ignorance, and neurotic personality, it worries me a little, especially  with respect to native mole crickets, although studies do show them to resist the wasp, so that risk is probably, if not certainly, low.   Spermacoce verticillata is so ubiquitous already that cultivating more is not likely to cause additional harm.

Spermacoce verticillata 4

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Relevant link for extra info

 
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Posted by on August 26, 2017 in Buttonweed, Uncategorized

 

Sea-Purslane and the Sucky Salt

Sesuvium portulacastrum

(Sesuvium references an ancient Gallic tribe.   Portulacastrum notes false similarity to Portulaca.)

Aizoaceae

 

A  romantic stroll on the beach in Florida or throughout much of the warm climate world may reveal a trailing succulent with showy purple-violet flowers. The fruit opens like the lid of a Weber Kettle to allow seeds to splash out, much like the pod of its namesake Portulaca.

Sea-Purslane sometimes goes by the name Sea-Pickle.  Plant munchers eat the salty succulent leaves.  Perhaps not a grand idea, however, as the tissues are powerful mercury (and probably lead) accumulators, not to mention producers of steroid hormones.   A few words on those:

Twenty-hydroxyecdysone is a steroid touted for boosting testosterone for virile body builders. I think the claim is spurious, and who wants to go around ingesting hormones?  If John and I become more manly we’ll be dangerous.

Sesuvium portulacastrum 1

Photo by John Bradford.

Why would a plant make animal-active steroids?  Twenty-hydroxyecdysone is an insect molting hormone, serving to disrupt insect development, thus perhaps a future natural insecticide crop.

Insect damage to Sea-Purslane was the object of a hurricane recovery study in the Bahamas where hungry moth larvae undaunted by hormones stifled hurricane recovery by eating the pickles faster than they regrew.    What saved the day was a population of Brown Anole lizards, native in the Bahamas and introduced and established abundantly in Florida.  They had the fever for the flavor of a caterpillar.

It is always curious how plants of salty places cope with all the salt.   Some secrete it one way or another.   But Sea Purslane stores it!  Exposure to salt, in fact, up-regulates hundreds of known genes and enhances growth. The plants sequester extreme salt concentrations within the thick leaves, in the vacuoles to be exact.  A vacuole is sort of a bag inside a plant cell, and stashing the salt there may cut down its damage to basic cell functions.

The “purpose” of the stash however is not to place the salt out of harm’s way, but rather it seems using it in a “fight fire with fire” strategy.   The beach sand is highly salty of course, and that draws water out of the roots by osmosis.   You might say “salt sucks.”  People have long known that salt in the soil kills plants.   To smite the Sichemites, sow salt on their fields and dehydrate the crops.

Sea-Purslane fights salt with salt.   If a high soil salt concentration forces a tug-o-war for water, the way to win is to have even more sucky salt in the leaves.    A thick stand of Sea-Purslane can take up enough salt to diminish meaningfully the salt concentrations in the soil,  an observation not overlooked in soil reclamation.

 
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Posted by on August 18, 2017 in Uncategorized

 

Down and Dirty

Bulbs, Corms, Stolons, Tubers, Turions, and Bulblets

(Some of today’s images are from our earlier blogs in different contexts.)

Today’s topic is the suggestion of Pasco County Biologist Katie MacMillen.   As John and I explore the hottest, driest, wettest, most disturbed, and most fire-prone habitats, we see a recurrent theme, as Katie noted:  all manner of subterranean contrivances to allow plants to recover after trouble above…be it fire,  sun,  frost,  flood, or fauna.    We explored Halpatioke Park today for insects in a low area sometimes submerged sometimes dry.    A perfect rhizome zone!

Patience please!  A quick vocabulary lesson:

A rhizome is a horizontal stem usually beneath the ground level.    Tasty example, ginger “root.”

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Torpedo Grass rhizome

A stolon is thin rhizome running across the ground surface.  Familiar example, runners connecting grass clumps.

A tuber is a thick fleshy rhizome or an expanded rhizome tip.   For instance, potato, or caladium “bulbs.”

A corm is a short thick vertical stem just below ground level.  Garden example:  Gladiolus “bulb.”

A bulb is a thin vertical stem surrounded by layers of thick fleshy leaf bases. Routine example: onions.

The common names for these structures are messed up and confusing.

In the local native flora we have it all:

The hunkiest local rhizomes might be those of Spadderdock, Nuphar,  several inches in diameter and several feet long.  In addition to surviving dry times, the big rhizome has an astounding second function.  Spadderdock  has pressurized airflow with some leaves taking in air and forcing it downward through the leaf stalk and then through the rhizome,  eventually back out through other leaves.

frogs-on-nuphar

Somebody is sitting on the Spadderdock air intake

 

nuphar rhizome2

Spadderdock rhizome

 

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Also well endowed rhizome-wise, Smilax  may have more biomass below ground than above.     It can pop up vigorously after a fire, often climbing the charred remains of its former competitors.

Smilax auriculata 2

Smilax tuber. By John Bradford.

The aquatic emergent Sagittaria has textbook tubers, sometimes called “duck potatoes.”  And they are tasty like a tater.    So are the nuts (tubers) from the exotic weed, Yellow Nutgrass.    Those who cook it call it Chufa.

Weeds are adapted to existential threats.  Survival can be via tubers…ha ha you can’t yank, burn, or graze me…because I’ll rise from the ashes.  The comely lumpy white tubers of Florida Betony (Stachys floridana) give the plant the name Rattlesnake Weed.

One of the worst weeds ever is Tuberous Sword Fern, combining the ferocious dispersal power of wind-blown spores with the immortality of tubers.  Who said, “you can’t predict which introduced species might escape and become weeds”?

Some plants use tubers not just to persist, but also to spread, especially easy in aquatics such as the invasive pest Hydrilla, which in addition to float-away tubers has secondary smaller tuber-like units, called turions.

An odd tuber(ish) structure forms while a Live Oak is a mere baby, in its youth susceptible to ground-level hazards before achieving mighty oakdom.

Quercus tuber 1

Tuber on Live Oak youngster. By John Bradford.

Corms happen here too.   For instance,  Blazing Stars,  Liatris species survive the trevails of exposed life via the dark underbelly of corms.    If you buy garden Liatris you are most likely to buy corms marketed as “bulbs.” Likewise cormish is the Aroid Family, for example, Jack in the Pulpit and Arrow-Arum in Halpatioke Park today.

Liatris gracilis 5

Liatris corm by John Bradford.

And then come bulbs, especially in the Lily Family and relatives:  Catesby’s Lily and Spider-Lilies are all native local bulb makers.   Our Halpatioke site today had bulb-bearing Crinum Lilies all abloom this morning mixed with rhizome-rich Cannas.

The introduced pink woodsorrel makes tiny bulb(let)s near the root-stem interface and elsewhere.   The species makes no fertile seeds, the bulblets seem its sole means of reproduction and dispersal.

Why is all this underground business based on stems?  Isn’t the dirt the domain of roots?  Sort of.  There are plants with creeping roots and thick storage roots, such as sweet potato, or its big-rooted native relative Largeroot Morning Glory.   But stems have a more versatile, more diversified, more flexible structure than roots, so when evolution messes with a plant’s structure for a novel purpose, “stem” appears to be a better starting point than “root.”

Why do so many wetland species have so many rhizomes and tubers?  Aren’t they safe in their nice moist marsh?   For starters, where we encounter a species is not necessarily reflective of where it evolved.    After all, most of Florida was under salty seas a few thousand years ago, so our marshy  friends mostly evolved elsewhere before settling into Florida.

Secondly, a lot of shallow-water plants face intermittent drying.   Pine flatwoods are full of summer ponds-winter meadows.  Many evolved on shores or littoral shallows with fluctuating flooding, drying, and disturbance.  Also, excessively deep water could be a foliage killer.

Yet another advantage of underground rhizomes for aquatics is a relentless war for space.   When you look at an open shallow body of water there are immense single-species clonal clumps covering acres pushing and shoving with other massive clumps.  Reminds me of 2017 politics, including the subterranean aspects.  Victory requires spreading aggressively by rhizomatous growth, by rhizome fragmentation, and by territorial turions.  Go forth and multiply.   Seeds are good, but rhizomes are better at pushin’ and shovin’.

species competition

Two armies at war.

 

 
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Posted by on August 11, 2017 in Rhizomes, Uncategorized

 
 
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