Root Tracks,  Wellwater Stains, and Petroglyphs

Today John and I visited Halpatioke Regional Park near Stuart, Florida, preparing to guide a wetland field trip there in January, maybe.   Wetland fieldtrips lead quickly to soil ecology, and that means bacteria.

In the wet prairies and depression marshes near us the hydric (perpetually saturated) soils have a characteristic vertical profile.  The top layer is black peaty decaying plant matter, which may vary in thickness from 12 feet historically in the Everglades to an inch around our area.   Below the decaying peat, the absence of oxygen due to constant saturation creates a comparatively sterile off-white layer whose whiteness is enhanced as minerals wash down to lower levels.  Below the sterile white zone appears a second blackened band of organic acids collecting from the decay up top.  Markings may stain the white zone, and those can be interesting…stay tuned a moment.

Soil 1

Hydric soil profile.  Dark peaty layer on top. Sterile leached white layer below.  Edge of second dark layer at bottom of photo.

Our official Florida State Soil resembles the sort I’m describing, Myacca Fine Sand.

Now back to the markings.   To repeat hopefully helpfully, the whiteness is due largely to absence of oxygen, yet penetrating roots may channel a little oxygen down there.  Bacteria along those root paths obtain energy by using oxygen to metabolize manganese (and iron), much as I use oxygen to metabolize a raspberry danish.   You might say the bacteria harness the natural process of “rusting.”   The oxidized manganese shows up as black root tracks in the otherwise off-white soil layer.   Manganese and iron can oxidize without bacterial assistance, of course, but the association of manganese-oxidizing bacteria with wet-soil root tracks is well established. The bacteria concentrate the oxidized metals.  In fact, there are cases where the wetland bacteria tie up enough manganese and iron to cause the plants nutrient deficiencies.

soil core 3 root track

Root track penetrating the white layer.

In some areas “iron bacteria” in well water cause their own markings…orange stains on surfaces exposed to iron-rich groundwater.  Again, bacteria are obtaining energy by oxidizing iron, accumulating the reddish iron oxide within the bacterial colonies.  Immediately behind my home is a municipal pump that discharges groundwater intermittently into a small canal where it mixes with other water.   The pumping apparatus has reddish iron bacteria stains. Look at the red stain on an otherwise white pipe in the photo below.   The stained zone houses “iron bacteria” of the genus Gallionella with characteristic expanded heads on kinky, branched stalks.   They are very very very small, yet visible in the photo below.

pipe with stain

Pipe stained by iron oxidizing bacteria. The white line in the stain area is the site scraped for the next photo.

Gallionella 2 circled

The Gallionella stalked bacteria from the orange stain on the pipe. (I believe…although I am not an expert on bacteriology!)

Last week my wife Donna and I were in Nevada exploring the desert and mountains (and losing a couple bucks in Las Vegas).  Manganese bacteria stained there too.  Desert rock surfaces sometimes have a gloss the same color as those dark tracks in the Florida hydric soils.    The “desert varnish” is likewise the work of manganese-oxidizing bacteria, mixed with other microbes.   The varnish builds so slowly that petroglyphs in it by pre-European artists remain vivid still, thousands of years later.

Desert varnish on big rocks

Rock varnish in Nevada.


Desert varnish petropglyphs

Petroglyphs in Nevada rock varnish, probably over  2000 years old, although the age is not precisely established.

Funny how the same natural phenomena surface all over the place once you’re looking.  Root tracks in waterlogged soils, red stains around wellwater plumbing, and ancient petroglyphs all the handiwork of iron- and manganese-metabolizing bacteria.


Posted by on December 22, 2017 in Soil bacteria, Uncategorized


Jack-in-the-Bush Leafminer (Might Take Ten Years Off Your Face)

Starring  Chromolaena odorata as the plant

(Chromolaena means colorful cloak.  Odorata denotes fragrance.)

Asteraceae (Aster Family)

With Cremastobombycia chromolaenae as the miner

(Cremasto means suspended.  Bombycia means reed, or flute made of reeds.  Chromolaenae refers to the plant host.)

Gracillaridae (Leaf Miner Moths)

Today’s botanical hotspot was the Jupiter Ridge Natural Area at Jupiter, Florida, a large sunny scrub with a marsh in the middle, plus a tidal creek.   Habitat diversity translates into biodiversity, making the site a great place to go.    The pretty flowers today were escaped horticultural water lilies in pink and blue, picture perfect and fragrant abuzz with bees, but we’ll feature a more mundane creature.   Leafminers were at work, and intriguing if not eye candy.  Leafminers are larvae of various insects trapped for a portion of their youth tunneling through leaf tissue, feasting on salad protected from the harsh world.  Arthropod boarding school.

Chromolaena odorata 1

Jack-in-the-bush by John Bradford

The most conspicuous of the miners at this season infests a large native weed coming into its Holiday blossom time, Jack-in-the-Bush.  Its miner-miner 49er has two remarkable truths:

  1. The insect ducked formal “discovery” until 2013. (Nobody cares about a worm in a weed.)
  2. The larva is not satisfied with a mere tunnel. Instead, it excavates a huge white blotch separating the upper epidermis (skin) from the tissues below.   Sometimes the blotch covers the entire leaf surface.  A heavy infestation resembles ornamental variegation.
leaf miner larva in mine

Blotch with culprit. The miner is under the epidermis.

You might wonder how a tiny caterpillar can undermine a big area.   It swings its head vigorously from side to side like a reaper with a scythe.

Watch the little swinger here:  CLICK

At this juncture the discussion broadens from the single species pair to miners in general, remembering how they represent diverse major insect groups.  So what I’m about to say applies to some but probably not all.     Leaf miners have a problem…they might outlive their host leaf.

Chromolaena odorata 7


Heaven forbid, what happens if the leaf ages and drops before the little feller completes its tunnel time?   That brings us to the botanical anti-aging hormones, cytokinins (SIGH-toh-kine-ins).

cytokinin creme

I doubt cytokinins  are a fountain of youth on human epidermis, but they do work on plants.

CLICK here

If you are a parasite  inhabiting a leaf, you wish your blade a long healthy life.   Leaf miners do more than just wish, they promote foliar youth and longevity.  Although I have trouble finding convincing photogenic examples in South Florida, farther north where leaves seasonally discolor and drop,  leaf miners release cytokinins to insure their home, or at least the miner’s mineshaft region.   Such green areas housing miners surrounded by deteriorating leaf tissues are called green islands.   CLICK to see one.  The miner is at the lower right corner of the island.

We must wonder if the miner is merely protecting its lair from routine leaf aging.   Alternatively (or additionally), perhaps the life-extending hormone therapy mitigates the miner’s damage.

It gets more complicated.  Does the miner make the cytokinins, or does it cause the leaf to?   Or maybe neither:  There is a third factor in the equation;  it seems the miner can’t prescribe the cytokinin rejuvenation without the help of symbiotic bacteria.  In short, all three species are involved: bacteria, insect larva, and plant.

miner larva exposed



For those wishing to burrow deeper: MINE THIS


Posted by on December 8, 2017 in Leaf miners, Uncategorized


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Pitted Stripeseed –  Four “Species” Really Just One With a Complex History

Piriqueta cistoides subsp. caroliniana

(Piriqueta is a Guyanese common name for this species or close relatives. Cistoides comes from an ancient plant name.)


Today was the reason snowbirds flock to Florida…perfect.  So John and I chased biodiversity in the Juno Dunes Natural Area in Juno Beach, Florida.   Hiking from habitat to habitat, one of the sights and sites to behold was a wet meadow dominated by butter-cuppy yellow Pitted Stripeseeds, showy wildflowers always a joy to encounter, especially as a single-species flower garden.

Piriqueta cistoides 3

Piriqueta by John Bradford.

Single species?  Back in the 30s iconic Florida botanist John Kunkel Small perceived four Piriqueta species to grace our state. My, how things change, with contemporary botanists smooshing all that variation into a single subspecies.

Piriqueta cistoides 2


Such aggressive lumping begs the question of, “how did all that variation happen within a species?” We’re not the first to wonder.  Several botanists spanning decades, prominently S. D. Maskas,  M. B. Cruzen,  and DNA have explained the Piriqueta history in peninsular Florida, so much more interesting than merely gerrymandering variation into classification categories.   Here’s a thumbnail version of complexity:

Apparently on three separate occasions separated by vast spans of prehistoric time different representatives of our subspecies immigrated from the Bahamas.  One arrival wound up in southern Florida near us (call it T).  Another wound up in northern Florida and beyond (call it C).  And the third arrival spread across southern Florida mostly south of Lake Okeechobee (call it V).

Piriqueta cistoides 4


Variant V migrated northward invading C, with the two hybridizing willy nilly across most of central Florida creating a complex and widespread web of variation, complicated further by changing habitats and by human activities.

Oh, isn’t that just weird.  That comment about vast spans of time matters. This is a case where one species re-encounters itself  at different points in its evolutionary history.  You could make up a sci-fi movie about that and humans…maybe some isolated peninsula where long- long- long-separated human lineages come together…….

Oh yea, it happened, right here in Florida didn’t it.  First came Native Americans via the Bering Strait, then they met up with Ponce De Leon.   We are human Piriquetas.

To turn now to a different angle…

The Florida Piriquetas, unlike those in other regions, have an odd adaption to promote cross-pollination.  Called heterostyly (het-err-oh-STYLE-ee), the condition divides the species into two different mating strains.   The flowers of one strain have a short style (where pollen is received) deep in the flower and long stamens (where pollen is made) toward the floral entrance.  The other strain is the reverse, with long styles protruding and short stamens deep in the flower.

Let’s say that a visiting bee pushing headfirst deep into the flower picks up pollen on its nose from the short stamens. When later it visits a flower from the opposite strain the pollen on the bee’s nose is at the correct height to brush off on the short style.  While there the bee picks up pollen on its protruding rump from the likewise protruding long stamens.  That rump-borne pollen is positioned to drop off on a long () style.   So then, cross-pollination ensues.

piriqueta pin

Petals removed.  Short stamens, long styles.

piriqueta thrum

The opposite—long stamens, short styles

piriqueta cluster


Posted by on December 1, 2017 in Pitted Stripeseed, Uncategorized


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Myrsine cubana and the junky trunk

(Myrsine is an ancient Greek name for a shrub, and may trace back to myrrh.  Cubana refers to Cuba.)


(Readers will find this plant under divergent species and family names.  It has a messy history.  Here we follow the Flora of North America.)


John and I wandered dodging cacti over sunny hill and sandy dune in the scenic Jupiter Lighthouse Inlet Lighthouse Outstanding Natural Area today, formerly a Coast Guard LORAN navigation station by Tequesta, Florida.

Our local Sahara Desert scrub is always a living museum, at least when not 94 degrees, and likewise interesting is the interface where scrub meets mangrove seashore.    Such borders are often home to a mixed bag of species.   Today there in bloom was Myrsine, a shrub popular among native landscapers decoratively and as birdfood.  Our species is just one of approximately 300 species of Myrsine.    In Florida Myrsine cubana favors near-mangrove areas and coastal hammocks.

The flowers are mostly unisexual, and many folks describe the species as dioecious (dye-EE-shus), that is, with separate male and female individuals, although the truth is more complex.  The authoritative Flora of North America avoids tagging it as that.

Rapanea punctata 3

Myrsine stems with flowers, by John Bradford.

The little cream-colored flowers sit crowded along older woody branches, partly hidden among the leaves.    Somewhere along the line my students started describing it as having its “junk on the trunk” (hey, don’t look at me), although I don’t think the trunk itself has flowers.

Myrsine flowers

Myrsine flowers today.

The term for bearing flowers and fruits along older branches or on the trunk is cauliflory.  Familiar examples include chocolate, jaboticaba, and mastic, or for northerners, redbud.   Cauliflory turns up sporadically among the flowering plants, having evolved independently in many different families.   Why?

There is probably no single reason, although botanists seem to find the condition mostly tropical, and probably with at least three benefits in addition to  strurdiness:  1)  In a tropical forest having a multitiered canopy many insect pollinators live “down low,” not out at the tips of the ultimate branches.    2.  In a tropical forest, not all potential pollinators fly.  Stem-borne flowers invite pollen dispersal from crawling insects, lizards, small mammals, mangrove crabs, and treefrogs.  3.  Birds don’t always fly; they also sidestep along branches.  That could help distribute pollen, and more importantly, perching birds as well as rodents can feast on the thousands of small black berrylike Myrsine fruits and help disperse the seeds.

Rapanea punctata 1

Junk on the trunk, by JB.


Posted by on November 17, 2017 in Myrsine, Uncategorized


Strap Fern Sitting Pretty

Campyloneurum phyllitidis and other epiphytic ferns

(Campyloneurum references curved veins, and phyllitidis refers to an ancient name for a fern.)


Today’s botanico-adventures were in the Cypress Creek Natural Area near Jupiter, Florida, working on John’s photo guide to the natural areas.     There are small, old, concrete culverts and water control structures, long neglected and overgrown, now shaded hideaways for mosses and ferns. An exceptionally attractive fern perching on a mossy old dam is Strap Fern.

Campyloneurum phyllitidis 5

Strap Fern on a tree.  All photos today by John Bradford.

Of course the fern did not evolve with decaying concrete to colonize, and its true calling is as an epiphyte on branches, rotting stumps, and most compellingly perched on cypress knees.

Cypress knee with strap fern 2

On a cypress knee.

Florida epiphytic (living up on other plants) ferns are prime examples of diversified adaptations to meet the same goal…survival with no roots in the soil.   Most of the epiphytic ferns here have some oddball features to thrive high and dry.

Most famously, Resurrection Fern, in addition to tough leathery leaves and water-retentive scales, has the supernatural ability to go into suspended animation when dry, and then to “resurrect” on a rainy day like today.

Pleopeltis polypodioides 13

Resurrection Fern.

Most weird-lookingly, Shoestring Fern dangles from tree trunks, usually Cabbage Palms,  as narrow strands like hair hanging from a head.   I think its main protection from drying is having its stomates (pores where water departs from leaves) hidden in a groove under a curled leaf margin.    With its stomates thus blocked, the fern retains its water, but then can’t cool evaporatively, which may be why the leaves are skinny “shoelaces” with huge collective surface area cooled in the breeze.  Air cooled not water cooled.  Less conspicuously, the fern roots penetrate the decaying tree “bark” and associated tissues aggressively, using the soft wet outer tree trunk as a substitute “soil.”

Vittaria lineata 2

Shoestring Fern.

Most robustly, Golden Polypody Fern sends long thick rhizomes wrapping all over its host (usually Cabbage Palm) trunk.   It seems to make up for not having a root system in the ground by making a large “root system” up on its host.  Who needs soil when you can probe the moist earthy world of old palm leaf bases?

Phlebodium aureum 1

Golden Polypody

Today’s fern has its own peculiar adjustment to epiphytic life.    We need a little history to understand.   DNA study shows Strap Fern’s ancestry to be more-typical looking ferns with divided “ferny” leaves, whereas Strap Fern evolved undivided leaves, just long  entire-edged straps, usually fairly erect.

Here is where we depart from specifics on Strap Fern and expand to broad generalities seemingly applicable to the present case.

Botanists think that ferns with funnel-shaped clusters of undivided leaves have evolved to funnel water and nutrients caught from the rain and leafdrip.   A fern rooted in the soil can get water and nutrients it needs from the earth.  Its biggest problem might be distributing enough light through its leaf system, which might explain why most shade-dwelling  terrestrial ferns have frilly divided leaves…to let the light through to lower leaves.

But an epiphytic fern, by contrast, has lifted itself up into a brighter habitat where light is comparatively adequate, but needs to capture all its water and nutrients from above and direct them to its small and superficial roots.   The leaves evolve consequently from lacey to strappy.   Beyond ferns, many flowering epiphytes have that funnel shape:   some anthuriums, bromeliads, and orchids for example.

Campyloneurum phyllitidis 6


Posted by on November 10, 2017 in Strap Fern, Uncategorized


Cypress as Old as the Tower of London

Rare treat today.  John, Dee Staley, and I joined the Friday tour of Barley Barber Swamp near Indiantown, Florida, led by Treasured Lands Foundation Director Chuck Barrowclough.   So much to see and learn there, from an ultra-modern solar-gas power plant to an ultra-ancient Seminole fish-catching canal.

Taxodium distichum 2

Cypress cones, by John Bradford.

Anyone can register for a tour through the Foundation’s web site, then don’t skip the best lunch in town at the historic Seminole Inn in Indiantown, former equestrian home of Davy Jones of the Monkees.

The swamp has unique attributes:

  1. It occupies a specially preserved peninsula jutting into the immense cooling pond for the Florida Power and Light Martin Power Plant, where they prefer solar by day and natural gas by night.
  2. There is a U-shaped Seminole “mound” apparently constructed to detain fluctuating waters from Lake Okeechobee, trapping the seafood catch of the day.
  3. Some Bald Cypress trees there are 700-1000 years old.  I looked up other things dating back so far.  Such as,  about that time the Byzantines did not get along with Bulgarians, so they blinded 24,000 of them.

Being a blog on native plants the responsible Barley Barber Swamp subject  is Bald Cypress,   famous for those conical woody knees poking up from the mud.  Because the knees already have a history in the blog, they get only a short review now, with details here.

Taxodium ascendens 8

The tree’s knees, by John Bradford.

I do not believe Cypress knees to have anything to do with serving as air snorkels to aerate the roots, or for propping up the trees.   I believe their actual function is boringly obvious, that these root outgrowths rise above suffocating water and mud to permit the basic metabolism required to pump sugars, not air (there are no air canals), outward into the underwater roots.   Sort of like the pumping stations situated serially aboveground to propel buried sewage lines.  All tree roots metabolize and pump sugars, but those in better circumstances do not have to come up for air.  Well, that’s how I see it.

cypress old

Around 800 years old.

So then a new topic for tonight.   I encountered “pecky cypress” several years ago, not in a biological context, but rather decoratively.   Today its biology stared us in the face.   Pecky cypress wood is riddled with isolated vertically elongate cavities.

cypress pecky

Pecky cypress in the swamp.

The cavities are the work of wood-rotting shelf fungi, probably best referred to as Laurilia taxodii (Stereum taxodi).  Their identity, classification, and nomenclature is a tangled web beyond the scope of tonight’s good times.     More interesting than their classification is a glaring matter of decay:

Why does the fungus not decompose the wood evenly?    It carves well defined scattered hollows leaving the wood between strong, healthy, and uninfected.  Not a new question.   Back in 1900, before the Wright Brothers, botanist Hermann von Schrenk in St. Louis probed the question for 54 pages in painful anatomical detail.  Anyone reading this would quickly dismiss the notion held by some that the tree and fungus have a symbiotic relationship where the fungus provides water-storage pecky chambers.   There is nothing in von Schrenk’s research, or any clear basis in plant anatomy or physiology for that.

Instead, Hermann found something more remarkable, which it would be a joy to see re-examined with modern techniques.   To make a long investigation short, he found the cavities free of water and to contain brownish dusty material resembling humus in the soil.   By this he meant dark-colored organic acid compounds, not the compost many gardeners refer to as “humus.”   Noting that humus can prevent decay, and citing human remains mummified for centuries in it, von Schrenk thought the fungus transforms wood to humus-like material that coats and kills the fungal strands, thus stopping the infection before it expands far.    The decay holes remain small because they spawn their own termination.

Who knows, and this is utter unabashed speculation, maybe the tree benefits from the peckiness because it lightens the weight of a thousand-year-old top-heavy shallow-rooted giant whose biggest risk to life and limb is toppling.



Posted by on November 3, 2017 in Uncategorized



False-Foxglove, Pretty tho a Little Sneaky

Agalinis linifolia and related species (about 11 species in Florida)

(Agalinis comes from Greek for “resembling flax,” linifolia refers to the linear leaves.)

Orobanchaceae (traditionally Scrophulariaceae)

Heavenly weather today, at long last, so I helped John with his megacool photo guide to local natural areas.  An opportunity to visit Jonathan Dickinson State Park near Hobe Sound, Florida that was.

JD Park

Jonathan Dickinson State Park.

Plenty in flower now, with the fairest of them all being False-Foxgloves with polka-dotted,  yellow-streaked, ticklefuzz-enhanced, purplish blossoms all through a meadow.  What red-blooded bee could resist?

Agalinis looking in

The white rod sticking out is the style and stigma, responsible for incoming pollen.  Behind it you can see 3 (4th one hidden) downturned points. Those are the stamens in two pairs.

The inner flower structure reveals a feature known as didynamous (dye-DYE-neh-mus) stamens, which is a botanical way of saying four stamens in two pairs of different lengths, the members of each pair clinging edge to edge.   Stamens are the pollen-making organs.   The two different-length stamen pairs apparently cater to different types and sizes of bees, and if you look closely the longer pair  is a little different from the shorter pair.    Having the two members of a pair linked side to side demonstrably improves pollen delivery.

agalinis stamens

Flower with petals removed. The long hairless white bar on top is the style.  The two shorter hairy units are the stamen pairs stuck together edge to edge, and of two different lengths and different orientations.

You can’t dig up the prettiest wild flowers in a State Park, so take the next part on faith.   These plants are hidden root parasites on neighboring plants.   The parasitic  root tips grab  victim roots and suck their vital juices just as a tick steals mine.

Gotcha! Agalinis root attacks its prey.    Photo by William Vance Baird.

Now all this begs the question of how the little sucker finds a root to attack, answered in part by recent plant hormone research.  The number of known plant hormones is expanding, and each new hormone has complex roles linked to other hormones.

A hormone family just discovered in the 21st Century is called strigolactones, part of a hormonal-genetic control system with remarkable duties.   This system detects smoke, switching on genes to kickstart seed germination upon passage of a fire.  (This suggests some low-tech experiments, although inconveniently complex variables may strike.)

Continuing the topic of underground detection, how does a plant root beckon beneficial soil fungi, “here I am ready to hook up” in a symbiotic relationship?    Answer:  Roots secrete strigolactone hormones into the dirt to entice fungal partners.    And, yep you guessed it, as biologist Caitlin Conn and collaborators documented in 2015, parasitic interlopers such as Agalinis intercept those hormonal solicitations, exploiting them to find the neighbor who was expecting a friendly fungus, not a sap-sucking parasite.

Agalinis linifolia 1

Agalinis linifolia by John Bradford.

Agalinis clump


Posted by on October 27, 2017 in Agalinis, False Foxglove, Uncategorized

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