Mud Dwellers are a Little Different

mud prints

Nature abhors a vacuum, including  muddy shores freshly exposed by the seasonal retreat of erstwhile shallow ponds.  Exposed barrens spell opportunity for ambitious pioneer species.   Colonization happens fast.  To meet plants you otherwise seldom encounter, don your boots and don’t sink in chin-deep.

There are no pre-existing competitors on new mud.  All newcomers can stake a claim.  Nobody is competitively excluded, so diversity abounds.  Let’s see, in the postage stamp mudhole I explored today I recall seeing (running out of fingers and toes) over 20 plant species.


Seedlings rising with no competition yet.  The last owner of that marine seashell was probably 15,000 years ago.

Who’s first to settle?  Floating plants carpet the receding water and are the first settlers, although the species composition shifts substantially.   The pudding-dwellers arrive for the most part floating as whole plants, or as little breakaway pups, or as fragments, or as seeds or spores.  The mud community is far more diverse than the species readily spotted afloat.

Green lowlifes on smelly mud take me back 470 million years to when plants originally strode forth from water to land.  Standing on the mud today was a window into pre-pre-history.  Look who we find, at least two examples of the most primitive still-existing plants, liverworts, straight out of a museum diorama.   I’ll bet today’s liverworts are almost unchanged from the first terrestrial plants, not counting bacteria and algae.

liverwort 1

Liverwort Riccia fluitans. Welcome to the time machine.  Bet it looked the same in the Ordovician Period.


Liverwort Riccia cavernosa.  Do the cavities facilitate gas exchange?  Any symbionts in there?   I’ve seen a lot of diatoms on/around this liverwort, but have no idea if that means anything.

The real fun is seeing who the castaways are and their adaptations to the mud world.  What are the facts of life on quicksand?  It is sopping wet, unless the sun bakes the surface dry.    The habitat is too suffocatingly soggy to invite extensive roots.    It smells like sulfur.   Nutrient acquisition must be a challenge.

At least one resident brings its own nutritional assistance.  The floating fern Azolla has folded into its leaves symbiotic nitrogen fixing Cyanobacteria, microbial fertilizer factories.   It can have all the nitrogen it wants.   The other floater in the photo below, Salvinia, has every third leaf modified into a big nutrient mop no doubt able to help with the fertilizer problem in its own fashion.

floating fern

Floating ferns love this stuff!  Salvinia with the big hairs on the right.  Azolla is on the left, with its internal Cyanobacteria.

The next rain spells doomsday for these precarious species, although each is ready for rainageddon in its own way.  They arrived floating, and can depart the same way, no problem?  What about those who came by seed and need to make new seeds?  They work fast.  The Pentodon in the photo below can bloom and fruit while still mere baby seedlings, not a moment to waste.   After that safe start,  the longer they live the bigger and more fecund they can be.

Pentodon pentandrus

Precocious Pentodon, flowering as a seedling.

The Ceratopteris ferns, water sprites, can float and make bulbils to disperse as clones, and even better, they mature from spores to reproducing adults in as little as three months to complete their sexual cycle.

Returning to seeds, one way to win a race is speed, as we just discussed, but there’s another way… a head start like the Nebraska Sooners.  Barnyard Grass, Echinochloa crus-galli,   jumps the gun by having the rare ability for its seeds to germinate in the absence of oxygen still submerged or buried in stinking mud.  That is why this grass is a pest in rice paddies.

Another response to re-rising water is to live with it. The Southern Marsh Yellow Cress, Rorippa teres,  sprouts all over the mud.  Not only does it flower and set seeds early in life, it can probably also live submerged if its relatives are a good measure.  Although I do not have data on this species per se, some of its close kin have survived and grown during underwater tests as long as three months.  Let it rain!




Posted by on December 8, 2018 in Uncategorized


On Line Free South Florida Native Plants Course Registration

Free! (except for book purchase)

Register now.  Begins January 7,  2019

By John Bradford* and George Rogers

  • 16 habitat-based lessons View the course at:
  • You’ll need our book: Guide to the Native Plants of Florida’s Treasure Coast by John Bradford and George Rogers.  To see the book, open Lesson 1, and click the link to the book vendor We make zero money from the book—any revenue supports our web site fees and printing costs, and nothing more.  Order now—delivery is slow.
  • Grab a field companion.  For each habitat type you take a field trip on your own with camera in hand. We list suggested field sites on the course web site. Most habitats span multiple lessons, so you DO NOT need a field trip for each lesson.  Your cell phone camera is fine.
  • The class evolved in Palm Beach and Martin counties. Students from anywhere are welcome, although the lessons are geographically biased.
  • There’s a quiz each lesson, and three exams.
  • The mission is learning to recognize wild plants. There is no attention to gardening, to landscaping, or to environmental issues.
  • Certificates of completion will be available to successful completers.
  • We proceed a lesson a week. We ask that participants keep up, although flexibility when “life intrudes” is the policy.   So feel free to take a trip or get the Plague.

To register or for more information George Rogers (    STOP!  BEFORE REGISTERING  read lesson 1 on   Make sure you know what you are getting into.   We’re not nice about people who register, take a seat, and then vanish!   If you are “in,” order the book with 3 weeks lead time.

Then send your name, e-mail, and cell number to George Rogers or   Registration is first-come, first served.   You will receive a confirmation.

Why a free class? Merely good green fun.   We have no interest in quibbling or rudeness, and anybody who can’t help keep it pleasant will get the boot!    This on-line class is an open-enrollment public-access derivative of George Rogers’s “Plants of Florida Ecosystems” (ORH2511) taught on-line and in the field at Palm Beach State College in Palm Beach Gardens.

 *John Bradford, although a co-creator of the class materials, will not be available for the Spring 2019 session.  Don’t worry, he’s not having a problem, and yes we are getting along.  In Lesson 1 please note that instead of to John all assignments are sent to George this session.


Posted by on December 3, 2018 in Uncategorized


What’s Cup Grass Have In Its Cup?

Eriochloa michauxii and related species

(Eriochloa is Latin for “woolly grass.”  Andre Michaux, 1746-1802, was a French  botanical explorer in the U.S., and elsewhere.)


A genus of grasses a treat to encounter around here, not that often, are the Cup Grasses, in the genus  Eriochloa.   Eriochloa michauxii is native, joined by a couple of uncommon non-native or marginal species in Florida.


Eriochloa michauxii by John Bradford

Overall, the genus is known for its adaptation to salty habitats, especially by possession of salt removal glands in some species, but that is not the main point of interest today.    Here’s the thing:

Why are they called “Cup Grasses”?

Each flower-fruit unit (spikelet) sits atop a little cup, like an egg in an egg cup.

And that being so, what good is that cup beyond helping with identification?



Botanists of yore thought the cup represented a modified leaf associated with grass spikelets (the lower glume), but no, the cup has emerged via fine research as an entity of its own,  curiously with a thin membrane around the rim.

Eriochloa cup

Microscope view of the cup and its rim (red bar).  The spikelet (containing flower, fruit) is the big green speartip rising from the cup diagonally across the image.

A cup, especially one with a thin extra lip around the rim must hold something.  It does…bits of fatty material, lipids, the membrane edge probably protecting the greasy contents during the collection phase.  I’m not sure exactly where the lipids originate to wind up in the cup.   Either the chalice makes the fatty deposits, or they drop in from above.   In any case, the enriched cup falls away with the spikelet at dispersal time and seems to be a goodie basket for hungry ants enticed by a fatty  treat to drag the spikelet with benefits back to their nests, thus dispersing the grass species.


Posted by on November 30, 2018 in Cup Grass, Uncategorized



Middle Aged Meadows and the Middle-Loving Plants

I’ve always loved sunshine, butterflies, goldenrods, and fragrances in cheerful meadows evocative of childhood memories.

Meadow Peacock

Meadows and butterflies, it’s only natural!

Attractive meadows in the Cypress Creek Natural Area near Jupiter, Florida, reflect several years of recovery after clearing and abandonment.   They represent a middle-successional stage.   Let me explain:

A textbook topic in Ecology is succession. Setting aside a couple controversies, the concept of ecological succession traces the history of a cleared area from its recolonization by annual pioneer weeds through a series of  plant communities onward and upward stepwise to a stable “climax” forest.      The stages and “final” outcome depend on the starting conditions, the basic habitat, and events.   The general trend with passing decades is from small and ephemeral toward large, heavy, and long-lived.


Today’s meadows represent a middle stage in succession.  A fairly predictable clique of species dominates such a mid-successional moist meadow.  What do the middlers have in common?    They are not just midway in successional time, but also in structure,  not exactly weeds,  pretty big, but not exactly hunky woody shrubs or trees either.   Tweeners adapted to life in the middle, just like 8th graders in Middle School.

As succession begins the pioneer weedy species compete mostly simply to arrive, persist briefly, and disperse seeds.   But conditions change, becoming more crowded with the incoming  species being ever-taller and broader.  Mid-succession competition becomes a fight for the light, the winners rising above those who came before.    Then still later at the climax community the competition shifts again, to bearing  youngsters able to cope with the canopy shade.

Let’s go back to mid-succession and that contest to rise into the life-giving light.  The perennial weeds in our meadow are fairly tall:   goldenrods, musk-mints, and bluestem grasses as tall as I am.    The species able to surpass those perennials often are bare toward the base where the sun don’t shine,  the foliage held at 4-10 feet as required to overtop the big weeds.   Achieving comes to require some degree of woodiness.

Meadow fennel

Dog Fennell with bare “bamboo” stems lifting the foliage above competitors.

The “beginner” of woodiness is Dog Fennel,  often with stems resembling bamboo, even by having “tubular” construction the stem becoming a slightly woody cylinder around a soft pithy core.   The stems live just one season yet become just woody enough to carry the canopy aloft.   The perfect balance between “fast cheap expendable growth” and height.  It can’t decide if it is a pioneering weed or a woody shrub, a little of both.

Meadow fennel pith

Dog Fennell almost hollow.

Also dominant are Saltbushes.   Along with Dog Fennell they represent the Aster Family which is usually non-woody, yet these Baccharis species have just enough woodiness to stand up and fight.    Relevantly, biologist P.B. Tomlinson, in his “The Biology of Trees Native to Tropical Florida” noted how  despite having a woody trunk, Saltbushes “more resembles an herb.”  He observed further that, “most of the woody branches are short-lived so that older plants are characterized by a mass of dead twigs.”

Meadow Baccharis

Saltbush, alive up high, shedding dead branches down low.

That tendency toward dead twigs sounds like abandoning crowded older growth in favor of new growth where sunlight is plentiful.   Saltbushes are not alone in tending to go bare down low.   Slash Pines appear as saplings early in succession, growing with the successional stages.  As they rise, the pines have an early bare base, and then begin a lifelong habit of shedding lower branches.  Observers usually interpret this as protection from ground fires, but that does not rule out a secondary benefit of lifting the leafy crown above rising competitors (which could fuel a ground fire).

Meadow pine

Another species sometimes prone to die down low  and  renew with tufts of leaves up high is Wax Myrtle, one of the dominant mid-successionists.   It and Saltbush have separate male and female individuals.

Meadow Wax Myrtle older

Wax Myrtle can dare to be bare below, with tufts above.

Wax Myrtle is one of the select few plants other than Legumes to have nitrogen-fixing root nodules,  giving it a competitive advantage on the terrible soils underlying the entire meadow.

Meadow nodule

On the Wax Myrtle root.


Posted by on November 16, 2018 in Meadow Succession, Uncategorized


Cypress Twig Gall Midges Make Big Blue Galls

Taxodiomyia cupressiananassa


What family has the most species in the animal world?   Here is a contender, observers estimate up to a million species in the Gall Midge Family, with over 1000 named in North America alone.  They are micro-flies able to induce galls on plants as larval homes.   Many arthropods make galls, and today’s galls are the big waxy-blue eye-grabbers of the Cypress Twig Gall Midge.

Taxodium stand

Bald Cypress

John and I were working yesterday in the aptly named Cypress Creek Natural Area, walking along the edge of a compelling Bald Cypress population.  This species has the most intriguing quirks, for instance some of the most “ornamental” galls I’ve ever seen.  The galls can be numerous, on the  tips of its twigs, looking from the distance like some ripening fruit.  They are the work of the Cypress Twig Gall Midge (and maybe sometimes a second related species).  It decorates Bald Cypress, Pond Cypress, and the Montezuma Cypress native to Mexico.

Taxodium branch galls

The galls look like Juniper “Berries”

Members of the Gall Midge Family in a general sense can be pests and parasites on plant pests, that is, they can seem to protect their host tree, a benefit employed in horticulture for natural biocontrol.  I don’t know if the Cypress Twig Gall Midge (CTGM) bugs other pests, probably not, but it does suffer its own parasitoids…parasites on the parasite.    The structure of the gall therefore no doubt serves to protect the CTGM larvae cowering within from parasitoids, and from larger predators.

Taxodium gall whole

What is the gall’s structure?  It is soft, spongy, surprisingly large, to over an inch long, and coated with a blue-white powdery material suggestive of ripening fruit.   Larvae embedded in it may be nestled safely away from most parasitoids and predators.   But there could be more to the gall structure.

taxodium gall open

Gall opened.  There are many tiny midge larvae per gall.

And with that, we enter the speculation zone.  Beyond protecting the larvae, are there additional reasons why the galls are big, lightweight and spongy, and colorful?   How about helping to disperse the midges?   Not just storage…but moving and storage.

Bird Dispersal

The galls are the color of juniper “berries” and suggest bird-dispersed fruits.   I don’t know if birds peck them, but there a hint of plausibility hidden in a small literature on insect larvae dispersing via a bird’s gut

Dispersal could occur even if a bird merely pecks at the soft gall or rips part of it free and drops an uneaten fragment elsewhere.   The midges reportedly mate upon emerging from the gall, so a gall chunk with even two of the average reported 16 larvae per gall could relocate potential mates together.

Rodent Help

The galls occupy  the twig tips.  The twigs are deciduous, so the galls land on the ground. Rodents and ground-dwelling birds, even large insects, could move them or fragments hither and thither.

Floating Around

The galls bob like corks, remaining dry and waterproof.    The twigs and galls drop more or less during the relatively dry season, but then again, it does rain during their “on ground” time, some places such as creek banks have  water year-round, and we don’t know the entire temporal-spatial history of the galls anyhow.  Maybe that waxy coating has to do with flotation,  water-proofing, and decay delay.

Final Mystery

As a closing note,  biologists George Washburn and Sunshine Bael last year found a connection between midge success and fungal diversity within the gall.  The galls are little fungus gardens.   Who knows why? Do the fungi help sustain or protect the midges?   Or do midge larvae in the gall promote fungi? Or both?  Neither?  Are larger galls merely better habitats for larvae and fungi?  Does the mother midge inject fungi during oviposition, and if so, why?


Dahoon Holly …the Dollar Tree of Fruits

Ilex cassine

(Ilex is an ancient name for an Oak.   Cassine comes from cassina, the Black Drink, see below)

Aquifoliaceae, the Holly Family

Ilex cassine 5

Dahoon Fruits by John Bradford

Beautiful autumn in the Florida woods: cool at long last, fall color in the Poison Ivy, goldenrods,  “asters,”  and Dahoon Holly berries (technically drupes) holiday festive in red, orange, and yellowish.  Lots and lots of them.

Dahoon Holly was the celebrity this morning as John and I chased ugly little weeds at the Haney Creek Natural Area a little north of the St. Lucie River.

Ilex cassine 8

The Dahoon had flowers today, by JB (this photo not taken today however). This is male, the males and females mostly on separate trees.

To take care of the “internet-type” story first, the species name cassine comes from cassina, the Black Drink consumed by prehistoric peoples at big shindigs along the southeastern coast, and by early settlers, including  future Philadelphia Mayor Jonathan Dickinson, not to his taste.

Hollies are among the few plant groups in addition to coffee and tea offering beverage-worthy levels of caffeine.  Around the world, there are holly-based teas, most notably Yerba Mate in South America and in Publix Supermarkets.   Our local holly tea was the Black Drink with two native species in the brew…Yaupon, Ilex vomitoria, and Dahoon, Ilex cassine.  The former may have been more important, although that detail is lost to history.

Ilex cassine lichen

Dahoon tends toward white bark,  often decorated with smiling red lichens.

Don’t bite a Dahoon Holly fruit or leaf.  They are astoundingly bitter, as I experienced today, resembling in flavor the related and well named Gallberry, Ilex glabra.  Chugging the Black Drink caused retching, after all. Why would such delicious-looking fruits, the colors of apples, taste like Athlete’s Foot medicine?

First of all, they may taste better to the deer, small mammals, and birds who eat them, although I do not believe it.   The fruits persist largely uneaten from autumn into the winter when the flavor presumably improves.  This is a general characteristic of Hollies, and observers contend that Holly fruits become tasty(er) during winter in order to sidestep the competing rush of fall-ripening fruits on other species.   Wait them out and be the only game in town later, perhaps matching the seasonalities of certain birds. Holly fruits are reportedly “cheap,” low in fats and sugars, and thus probably not very competitive when everything else is ripe in early autumn, and then more attractive later freed of  competition.  “We’re lousy fruits but all there is.”

Acer rubrum leaves Baker Rd.

While we contemplated the Dahoon today a posse of raccoons watched from a tree.   Whether or not they enjoy Dahoon fruits is unclear, and I did not examine their droppings for the characteristic “seeds,” which come four per fruit.


For the most part, Dahoon Holly is a species of marshes and swamps.  And that brings us to what I think is the interesting part:   these species are “at home” at every phase of ecological succession from soup to nuts.    Let’s stop a second and set the stage:

If you destroy a mature forest  (fire, storm, flood, machinery) and let it regrow, getting back to “mature” is step-wise,  requiring a series of communities occupying the site replacing each other over decades, from early “pioneer species” (mostly low weedy temporary plants) to the final woody “climax community.”   Dahoon Holly owns the entire process.  It is shade tolerant and can became a large tree in a mature forest community.  Upon becoming large it forms a broad base with prop roots.

In a middle-aged, shrub-dominated swamp or marsh, look for the Dahoon Hollies rising above the saw palmettoes, buttonbush, and wax myrtle.    And now the really good part: in an open, young,  perhaps fire-cleared marshy area dominated by small more or less herbaceous plants, such as Painted Sedges, Grasses, and Xyris, puny Dahoon Hollies merely three feet tall join right in and show off big lurid fruit displays. You could (and I have) mistaken them for milkweed flower clusters from the distance.    The little Dahoon Hollies seem to “prioritize” and invest disproportionate energy in reproduction while still toddlers.

Ilex cassine young 1

This tiny Dahoon  has more fruit than the rest of the plant’s mass put together.

What may allow this is that “cheapness” of their fruits as we just considered.  Maybe a baby can’t muster the energy needed to make garish displays of fatty sugary fruits, but cheap fruits…all show but no nutrition…hey, no problem, how many do you want?


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Spirogyra…Pond Scum On the Move

What do we have in common with Charles Darwin?   Wondering about the weird and beautiful Green Alga Spirogyra doing the hokey pokey, moving all about, a little surprising in a filamentous photosynthetic true alga.  What’s up with that?

If Darwin couldn’t figure it out, I can’t.  Perhaps there is no function to it, with the movement being a byproduct of growth?  Check it out and go figure:

See the Spirogyra in action in the brief footage below.    The video has been sped up 10X:

CLICK HERE   to see what Darwin saw (The tiny dancers are varied aquatic microbes.)

These freshwater algae have the world’s oddest chloroplasts, twisted like a ribbon running the entire length of each cell.  It must be a good arrangement, as there are 400 different species, having anywhere from one to many helical ribbon chloroplasts per cell.    We ask again, why?   It looks like the spiral shape might be a consequence of the overall cell growth pattern.  The cell wall grows in a helical pattern, and the shape of the chloroplast conforms.   Like a spring, it is stretchable…a “plus” in a cell with the rare condition of each chloroplast running the length of the cell.

Spirogyra chloroplasts.jpg

Those thickenings you see in the green chloroplasts are called pyrenoids (PIE-reh-noids). They are points of starch formation and storage.

Sometimes an algae-filled pond has a different look at the end of the day as opposed to dawn.   Some algae and so-called blue-green algae rise and fall on a daily cycle, sinking during the night and bobbing to the surface during the day.   In Spirogyra the simple and probably partially accurate explanation is that  during the day oxygen from photosynthesis collects in the algal mat, causing it to float upward.  That serves the alga well by placing it above the competition for sunbeams.

At night oxygen loss diminishes buoyancy, and the mat sinks.    I think I’ve seen the mat rise sooner under sunny conditions, delayed by shade.    You can see it too below.   The Spirogyra you’ll see is on my back porch in a closed plastic bottle about a foot tall.  It yo-yos up and down daily.    The rise recorded in the short time-lapse video below was in bright sunshine.    It resinks in the dark after my bedtime.  The dark bodies dancing around are time-lapse snails.

CLICK HERE to see the Spirogyra rise up


Posted by on October 21, 2018 in Uncategorized

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