Primrose-Leaf Violet

Viola  primulifolia


John and I went today to a favorite site, Kiplinger Natural Area in Stuart, Florida, to see what’s shaking on Groundhog Day.   Shaking were many small, near-the-ground wildflowers, each with a subterranean quirk:


Bluethreads (Burmannia biflora) thrives on symbiotic fungi underground.

Burmannia biflora 4

Bluethreads today in Kiplinger.  Except for seed and fruit, today’s photos by John Bradford.


Innocence (Houstonia procumbens), like a peanut, forms its fruits underground.

Houstonia procumbens 7



Zigzag Bladderwort (Utricularia subulata) eats its prey underground.

Utricularia subulata 9

Utricularia gibba  Bladderwort


But today is about a species spread all over North America, but not seen much around here:   Primrose-Leaf Violet thinks Feb. 2 is springtime, flowering and fruiting in moist nooks and sunny crannies.  There’s little in the world prettier than a violet, and this one is a stunner if you don’t mind tiny,  having bleached-white flowers decorated with purple nectar guides.

Viola primulifolia 4

Viola primulifolia flower2

Actually, not all its flowers are lookers.  Like most violets, today’s  has “cleistogamous” (kleist-OG-ah-mus) flowers, that is, small, hidden, self-fertilizing, and never opening…yet making fruits and seeds.  In other words, a plan B in case the main flowers don’t achieve proper pollination, and a system for cloning the mother plant.

Viola primulifolia cleistogamous

Cleistogamous flower never opens but does make seeds.

Cloning may not sound important, but keep reading:.   Although unproven so far as I can find, many botanists regard the Primrose-Leaf Violet as an historical hybrid between two other species.    If that is correct, at the time of origin the new hybrid may have had a reproductive problem.  With whom does a lonely hybrid exchange pollen?  And worse, hybrid plants often have partial or full sterility.  You know, like a mule.  Cleistogamous flowers remove those problems to let it go forth and multiply immediately.  Then over time fertility conceivably improved.

Viola primulifolia capsule 2

Another violet oddity is ant dispersal.     Having hungry ants haul your seeds back to the pre-fertilized pre-tilled ant hill is handy, unless the ants eat the seeds.     But no worries.  Some violets have toxic seeds, which might protect them from ant bites.  But are the ants thus disincentivized?   No.  The seeds gift the insects with a separate food package called an elaiosome (ee-LIE-oh-some) affixed to the seed, attractive and acceptable to eat.   Some seeds do not germinate until the elaiosome is nipped.

The photo below is a seed from the fruit capsule,  apparently  immature*.   The elaiosome seems to be forming on the left end, although my interpretation is a little speculative.   Ask an ant.

Viola primulafolia seed

Immature (?) seed. I think the elaiosome is on the left.


*Technical note.   Wish I knew why the violets have odd not-fully developed seeds in ripe capsules.  Maybe leftover duds after fully developed seeds dispersed?    Or abortive unpollinated ovules?  Or, maybe the results of some level of hybrid sterility?

Posted by on February 2, 2018 in Primrose-Leaf Violet, Uncategorized


Scrub Palmetto,  Peter Pan of the Florida Scrub

Sabal etonia

(Sabal comes from an old common name.  Etonia refers to the Eton Scrub area.)

Arecaceae (Palm Family)

Today John and I gave a damsel in distress a jump start, and then passed through Prosperity Oaks Natural Area, an obscure live oak hammock lost beyond redemption in the suburban sprawl of Palm Beach Gardens, Florida.    The area is home to large (by local contemporary standards) gnarly old live oaks and all their epiphytes, and the dank understory.    In the latter, down deep in the shade flourishes a curiosity, Scrub Palmetto.

Sabal etonia 4

Today’s photos by John Bradford.

What’s curious is the shaded habitat.    This little palm according to most life experience and plant manuals is a sun-lover usually in open scrub on white sand in the sun-baked company of saw palmetto, low scrubby oak species, Florida Rosemary, and Sand Pine.     So, wazzup  deep down in the dark?   Scrub Palmetto is presumably water-limited and slow growing, so maybe deep shade really is no special problem, conceivably  even beneficially protective.    After all, a lot of palms are shade-tolerant, and those broad leaves could collect light.

Were the little palmettos on the site back if and when it was open scrub before the oaks rose up and took over?  How long would that take?   Seems unlikely.  Or have the Scrub Palmettos wandered in unbothered by the Live Oak canopy?   I’ll put my money on that.

Either way, these dwarf palms are adapted to severe tough times, usually keeping their stems and growing tips subterranean,  protecting the key points from  mayhem, such as death by fire.

In an evolutionary sense, Scrub Palmetto is a local spinoff from its big ancestor, Sabal Palm the palmetto all over Florida, the state tree.   Sabal Palm, aka Cabbage Palm, is widespread,  variable, and  a full-sized tree.   Scrub Palmetto is limited to the Florida Peninsula,  uniform, and three feet tall.

Sabal etonia 4 (1)

Despite its ultimate stature,  Sabal Palm begins life underground, starting with what’s called “saxophone growth.”   Hidden safely during the formative years, its stem grows downward, exposing merely leaves aboveground but not the critical stem tip,  before eventually rising like nuclear blast survivors into the hot aboveground radiation.

Now let’s speculatively evolve Scrub Palmetto.  What if some variants of Sabal Palm in especially perilous extreme habitats never proceed beyond the exposed-leaves stage, keeping the stem tip buried permanently, and remaining small forever?    That is, living life juvenilized.   It may be that in a stretched historical sense, Scrub Palmetto is essentially a “Sabal Palm” locked in forever as a pre-teen.


Posted by on January 26, 2018 in Uncategorized


Gumbo Limbo, Frankincense, and Myrrh

Bursera simaruba

(Burser is a personal name.  Simaruba reflects similarity to a different genus.)



Today John needed photos of MacArthur Beach State Park on Singer Island, Florida.   Aren’t many places I’d rather go!    So many wonders to behold, right in the city:

The Danzigergracht anchored off the beach—waiting to come or go from the Port of Palm Beach.


Gulf Fritillary on Sea-Lavender today. How can a butterfly flutter around in beachside gale?

Butterfly on sea lavender

Limber Caper pod.


And the good old Gumbo-Limbo tree.  If there’s one local tree everyone knows, this is it, and thus food for my conviction that the botany of everyday plants is more interesting and less pretentious than rare selections we don’t often see (but usually can if we want to drive for miles and listen to botanical priests).

Bursera simaruba 1

Gumbo Limbo peeling bark by John Bradford

Any 5th grader could tell us about the colorful peeling Gumbo Limbo bark, you know, tourist-tree and all that.    Why have such bark?    Notions, which are not mutually exclusive, include “molting” from fast growth (doesn’t strike me as a likely explanation); or shedding pesky algae, liverworts, lichens, mosses,  fungi, bacteria, or insects;   or providing a thin surface for stem gas exchange; or allowing photosynthetic activity in the stem itself.  The photosynthetic role comes up scattered in literature on this and close relatives, and, after all, the result of the peeling is continued re-exposure of green bark.  The green portion of he bark is loaded with chloroplasts.

Bursera simaruba 2

GL as it looks today, by JB

What I like best about Gumbo Limbo is the subtle fragrance of the resin.   No surprise, given that Frankincense and Myrrh are likewise members of the  Burseraceae Family.  F and M are native to the Old World.  In the New World species of Bursera have a similar history making life smell better.


Frankincense tree, in Oman, courtesy of Pat Bowman

The resin in some Bursera species is sufficiently pressurized to shoot herbivorous insects in a “squirt gun defense,” reportedly squirting as far as six feet and lasting multiple seconds.

Bursera simaruba 7

GL flowers by JB.  Not taken today.  The flowers come in varied mixes of male, female, and combo.   Almost all individuals make some fruits.

The fruits look like clusters of small grapes.  Each has a three-parted cover that falls away to leave behind a single sharp-edged, hard, reddish seed attractive to birds. Oddly the seeds don’t seem to offer much food value, but rather serve as grinding stones in bird crops, according to tree biologist Peter Tomlinson.



Posted by on January 19, 2018 in Gumbo Limbo, Uncategorized


Nitella, Green Plant Forerunner?   Boosted By Weed Killer?

Characeae (A family of algae)

Halpatioke lake

Halpatioke Park, a lake.  What lurks below?

John and I have been enjoying Halpatioke Park near Stuart, Florida, getting ready for a group field trip in January, and possibly my Palm Beach State College native plants class.  Wonderful how many habitats can mosaic just one park, from marshes to riverbank, pinewoods, scrub, and more.    Sparkling lakes are embedded  in the forest, postcard pretty, feeling remote like a vacation destination.   Some have a surprising resident… in billowing green overwhelming masses…Nitella Algae.

Nitella mass

Plenty of Nitella.

Most of us see algae as green pond scum, never giving it much thought except in the fish tank, or as biofuel, or as a dietary supplement,  or tangling fishooks.    But this alga  and its similar cousin Chara are old players in the history of botany.   They are branched, like a “normal” plant, and have complex reproductive organs that look, without delving into cellular details, like something you’d expect on a land plant rather than on a pond scum.

Nitella mass close

Nitella mass in the lake,.

Aha!  You figured it out already:  land plants evolved from Green Algae.  Land plants have stems and branches.  So does Nitella.   Land plants have complex reproductive structures.  So does Nitella.

(All true of Chara as well.  Chara differs by  being stiffer, by having a rough stem, and by a characteristic stink.)

Nitella branches

Branches, as seen under a microscope.

When I was a student, textbooks suspected Nitella and Chara or more precisely their closely related predecessors to be ancestors to the land plants roughly 500 million years ago.   The ostensible ancestorship has been an area of speculation for years, and then came DNA analysis to spoil the fun.   Apparently Nitella and Chara lose their ancestral status.

Similar branchy structures with threadlike stems or leaf segments occur in several unrelated aquatic plants.  Such architecture helps keep any shallow plant attached to the mud, wafting in the waves, exchanging gases, and taking in the sun.   The earliest land plants, by contrast, were probably not branchy, but rather sprawled on the wet mud.

Very oddly for Green Algae,  Nitella and Chara make sperms and eggs inside protective sacs, as do unrelated marine algae.  The sperm and egg sacs are not clues to evolutionary ancestry, but rather mere demonstrations that protecting the family jewels matters when you’re near shore battered by waves and surviving fluctuating water levels.

Nitella egg and sperm

Egg making sac on the left. Sperm-making organ on the right.

In short, Nitella is adapted to occupy shallow lake shores, but why so much of it in the Halpatioke lakes!?   Are great green clouds of Nitella natural?   Maybe not.  One ecological study showed nutrient pollution to spur Nitella growth, at least temporarily, while suppressing its sexual reproduction.  Most lakes in South Florida have nutrient pollution, even nice secluded ones in Halpatioke Park, given pastureland all around,  the adjacent St. Lucie River,  fertilizer nutrients in the rain and groundwater.

And to end a little ironically,  the very weed killer spewed on an industrial scale to suppress unwanted plant life may contribute to the overgrowth in aquatic habitats.  Glyphosate, aka  Round-Up,  herbicide is a source of aquatic phosphorus pollution.  It can fertilize the enemy.


Posted by on January 5, 2018 in Nitella, Uncategorized


Knotted Spikerush All Over The Place (Yet We Scarcely Know It)

Eleocharis interstincta

(Eleocharis translates loosely as beautiful marsh-dweller.   Interstincta means speckled.  The basal leaf sheath is dotted with dark purple.)

Cyperaceae (Sedges)


Today’s botany time with John was in Savannas State Park near Jensen Beach, Florida preparing a friendly grass, sedge, and rush public workshop for the morning of January 13.  Join us!   CLICK for a link. 

Most of the park is beautiful, low, and marshy….and in this morning’s cool fog, mysterious.   The perfect encounter for emergent aquatics, which have their own peculiar ecology, such as by forming massive rhizomatous monoculture populations spreading until they engage in a slow-motion collision with opposing spreading species.  Knotted Spikerush  is one of the most abundant and conspicuous emergent species of open shallow water in South Florida, lining shores and blanketing acres giant marshland lawns.     But the species remains oddly under-studied.

E. interstincta 2

Knotted Spikerush, monoculture.  Today’s non-microscopic photos a mix by John Bradford and by me.  I’ve forgotten who took which.

Has it expanded like Cattails as a result of nutrient pollution?  Unclear.    Limited research fails to show much effect from varied nutritional levels, although there is room for far more data.

Eleocharis interstincta short stem

Short stalk with flower cluster, surrounded by tall stalks.  Not much wind down here!

A Spikerush oddity has bugged me for decades:  the flowering stems exist  in two distinct heights.  Tipped with a flower cluster, most are around a yard tall.    Others are mere inches tall, mixed with and “at the knees” of the taller stems.  Why stunted stalks?  To take advantage of two different pollinators?  This is almost certainly a predominantly wind-pollinated species, with those tall stems waving in the breeze.    But the shorties are tucked down far below the windy heights, maybe supplementing wind pollination by attracting insects  down in the shadows.  There are hints of plausibility:  the flower heads are showy white, and those on the similar Eleocharis elegans are fragrant.  (Fragrance in E. interstincta is subtle, or at a time I’ve not sniffed, or absent.)

E. interstincta inflorescence 2

Flower cluster at stem tip.

A likely alternative explanation for the height disparity might relate to fluctuating water levels, where the short spikes hold forth during the drier months, and the tall ones in the high-water season. This week during late December short stems are in full bloom, as in the photo above taken this week,  whereas the tall ones are instead forming or dispersing fruits.   Seasonality is consistent with insect visitors, but I’ll place my money on fluctuating water levels until I catch bugs in the act.

Now another mystery to ponder.  The stem tops cook under the tropical sun, but the lower regions, rhizomes, and roots lie smothering under water and mud.  How do emergent marsh plants ventilate the basement?    Many have pressurized air exchange.  The exposed tops pump fresh air down where the sun don’t shine, like mechanical pumps aerating a mineshaft.

Most marsh plants have open channels and/or porous ventilation tissue called aerenchyma leading from their airy tops to their suffocating roots.     In Eleocharis interstincta and some related species the stems are hollow except for thin partitions making the stem resemble a miniature bamboo.

Eleocharis interstincta partitions

The stem partitions have a bamboo look.

The disks are made of loosely packed cells permeable to pressurized gases, as I’ve tested by blowing through to make bubbles.    Additionally, as visible in the electron microscope image below, channels around the stem periphery may facilitate air movement.

Eleocharis interstincta 3_preview

Porous stem partition surface, scanning electron microscope image, courtesy of Dr. Robert Wise.

Having open tissue helps, but you need to force fresh air down deep, and to let exhaust escape.   Studying an array of emergents, plant physiologists have identified three main systems to force airflow.

  1. Wind blowing across broken stems lowers their internal pressure, this drawing in air from other stems less exposed to wind. Probably unimportant with today’s species.
  2. Engineers move gases with a “Knudsen pump*” that works by having a hot chamber connected by tubes to a cold chamber. The hot chamber expands the gases within, generating pressure, just like car tires have higher pressures when hot.   The cold chamber, by contrast, has diminished pressure, allowing gases to flow from the hot high pressure end to the chilly low pressure end, and then escape. In a spike rush, the warm chamber is the hollow stem portion up in the sun.   The cold chamber is the portion down in the cold water.    Knudsen pressure pushes warmed air down to the cool lower regions where it vents out.
  3. The inside of the hollow stem is humid due to submersion in water and because all stems contain water. Because the water vapor accounts for much of the gas inside the hollow stem, other gases are more concentrated outside.  As those outside gases move inward to even out their concentrations they add to the internal stem pressure.

Our local Knotted Spikerush has never been studied pressure-wise.  But it bubbles from the submerged base.

Eleocharis bubbles2

Bubbling underwater root on a clump with the top up in hot sun.

Bubbling is not definitive proof of pressure from the top,  but there is an even better indicator:  detailed quantitative study of the pressures and gases in the related E. sphacelataCLICK HERE.

Emissions from marsh plant roots appeared in the blog last week where manganese oxide stained the root paths at the hands of oxygen-using soil bacteria.  Oxygen released in the root zone supports favorable microbes and diminishes toxicity.

A tight-fitting sleeve rising as high as a foot wraps around the base of the stem and around the region where the stem base, rhizomes, and roots come together.   Perhaps the sleve prevents gases from escaping prematurely, although I’m just guessing.  Interestingly, in the much-studied marsh grass  Phragmites the basal sheath helps generate the gas pressure.

Eleocharis interstincta sheath

Knotted Spikerush purple leaf sheaths. Do they prevent gases from escaping prematurely?

After pollination, the small flowers disappear behind little scales where the fruits mature.  Like many marsh plants, the fruits are oddly attractive, having a beak on top, bristles rising up around the fruit, and a decoratively sculptured surface.  Such sculpturing is common, maybe even characteristic, of the fruits or seeds of unrelated marshland plants, so there must be something “good” about it.    Botanists speculate the waffle sculpturing may help the fruits (or seeds) cling to mud on the legs and bodies of animals, wading birds for instance, thus helping with dispersal. That might help explain the spotty geographic distribution of the species.

E. interstincta achene

Fruit, with sculptured surface,  surrounded by barbed bristles.   Built to cling!

*For the sake of technical correctness, I feel duty-bound to note that in an actual engineered Knudsen pump,   the gas molecules are more concentrated in the cold end, so there is a movement of molecules back toward the warm end.  How it works overall will depend on the inlets, outlets, and venting.


Posted by on December 29, 2017 in Knotted Spikerush, Uncategorized


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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