Does the Moss Really Grow on the North Side of the Tree?

(Does the lichen grow on the north side of the lamp post?)

Today’s blog is the result of John’s sharp eye and healthy exercise.  Riding his bike socially distanced around his neighborhood, he noticed something striking:   that multiple species of  lichens on the lamp posts are 100% confined to the north edge of the post.


North is on the left. Photos by John Bradford.

By contrast, when you look at the “moss” growing on a tree trunk…real moss, algae, lichens, liverworts, fern gametophytes…all the growth is scattered around the trunk irregularly and in response to such variables as sun and shade,  water flow patterns, lawn sprinklers,  bark texture, nooks and crannies in the tree, competitors, and who knows what else.   It is fun to try to figure these things out.   You often find lichens on the brighter exposed sunnier ridges, algae and mosses lower and shadier, and liverworts in “waterfalls” where branch crotches funnel water running down the trunk.

red lichen

Lichens on a bald cypress, by JB.

But John’s experience resembles a well designed experiment with variables suppressed, a uniform surface, and under that circumstance, the lichens show their true predilection…north side, period.

Examining the poles in the “heat of the day” we noticed the sun lighting up the south, east, and west sides, leaving  a shaded vertical stripe inhabited by lichens of the north face. Like me under my beach umbrella. A quick look at a website showing shadow patterns year-round showed…during the hot hours…the north to be shaded all year.   Landscape architects know this.   We used to do a lesson in landscape design class showing that some points in the yard virtually never experience direct sun during the bright hours.


The poles are black fiberglass (or have fiberglass sheath covering something deeper within). How different were the two sides of the poles on a sunny afternoon with the air temperature 78 degrees F?   We checked several poles, on the sunny sides in degrees F: 115, 113, 113, in contrast with the  lichen-zones: 91, 93, 89.

Just for interest, we checked a palm trunk in the sun. The south side was an arctic 93, and the north side was 86,  which might help explain lichens surrounding the palm in contrast with the light posts.

The absolute absence of life on the poles with surfaces exceeding 100 degrees as opposed to plenty of lichens with temperatures in the 90s agrees with a broad general perception that at about 95 degrees life becomes supremely stressful in terms of cell membrane dysfunctions and protein denaturation (damage).   With obvious highly adapted specialized exceptions… cacti in Death Valley, bacteria in hot springs,…sustained unmitigated temperatures over 100 could be predicted to filter out most life,  even tough lichens.


Posted by on April 10, 2020 in Uncategorized


Local Ferns

Note from George Rogers…a chart of local ferns by PBSC student Sydney Kenney….


ferns Sydney Kenney


Posted by on April 10, 2020 in Uncategorized


Native Tillandsias by Sydney Kenney

Note from G. Rogers:   Putting Covid days to good use…I like this creative chart by PBSC student Sydney Kenney.


Native Airplants


Posted by on April 5, 2020 in Uncategorized


Using Natives in the Landscape

By Jayme Rieuf

Note from G. Rogers:  This essay is by horticulture student Jayme Rieuf, written during the Corona downtime.   This is so true, and so well written, I felt moved to share it on the blog. Thank you JR.
Using native plants could arguably be the most valuable thing one can do for their landscape for many reasons. Native plants are classified as a species that occurs naturally and thrives in an area in which it originally evolved. Native plants in any given area, state or every country differ. To begin native species are in fact better conditioned to the local environmental conditions. An example of this would be Forestiera segregata also known as Florida Privet that has adapted to sustain in Florida’s hot sandy soils. Native plants on average use less water because they are established to conditions of the area. This saves water which is considered a very valuable resource.
Species that are grown in their native environment usually are not in need of as much assistance from crutches like fertilizer, pesticides or even excessive watering patterns. In convential landscaping most often pesticides are over used or wrongly applied, which can actually kill beneficial insects which may be doing good for your plants. Not to mention how terrible pesticides can be for the environment and the one handling the product. With native species the minimization of these products means less runoff into oceans, streams and even our drinking water, which improves water quality for humans and animals. But this also reduces risk to humans for the long term with less handling, inhaling etc. of such toxic products.
Maintenance is lower in Native vs. Conventional landscaping because mowing, trimming etc. is not needed as frequently, which helps reduce use of non-renewable resources but also protects our water and air quality. As the world evolves the importance of air quality is increasing. Air quality is protected with reduced emissions of air pollutants caused by things like the gasoline from mowers, leaf blowers etc. Natives definitely reduce maintenance. Landscaping with natives is a positive for the environment by making an area healthier and introducing diversity of seed spreaders and pollinators alike. Luring in different species of birds, butterflies and other insects and animals adds to the beauty of one’s property and helps out others. This also proves to be an opportunity to educate our neighbors or friends on ways they can improve their own landscape saving time and energy. That may even encourage some balance of landscape designs to add a touch of coordination between properties.
The most valuable reason for using native species in your landscaping is the fact that it saves you money, because they practically take care of themselves. Native species evolve for survival over many years. They have adapted and will continue to adapt to our ever-changing conditions. Native species are valuable to landscaping for a number of reasons, if people understood more about the advantages of going for a native landscape they may be more opt to do so. That is the beauty of choice however, some people are high maintenance like their lawns. Taking this natives class has honestly given me such an appreciation for the species that are actually “meant to be here”.
Coreopsis gladiata 3

photo by John Bradford


Posted by on April 4, 2020 in Uncategorized



Samolus ebracteatus

(Samolus comes from an ancient name for a related species.    Ebracteatus means there are no small leaves mixed with the flowers.)


There’s a special “breed” of wildflower that I love to see and ponder…species that start their lives in water and then wind up high and dry as the season dried out, often very dry…from one extreme to the other.  Such wet-to-dry types always have interesting tricks up their sleeves.  “Brookweed” is a semi-misnomer for today’s species.   Yes, you can find it in brooks, but you can also find it in dry deserts where water had accumulated previously, in salt marshes, and, in Palm Beach County, on dry sand baking in the sun.   It favors alkaline conditions.   Today you’d never know it has anything to do with “brooks.”

Samolus ebracteatus in dappled sun

The leafy rosette at the base looks like something straight out of Arizona, with thick, succulent, waxy-looking  leaves  in a twisty rosette with some red sunscreen.  The rosettes of most plants have leaves that lie flat against the ground—think of a thistle or a dandelion.  But the brookweed rosette has the leaves contorted so that they tend to face the sun edge-on rather than the more normal face-on, the contorted  configuration cutting down on direct solar radiation at mid day, and at the same time maximizing wind exposure, allowing cooling.

samolus ebracteatus on cam ranger

The white flowers are about ¼ inch in diameter on short stalks arrayed along a long wand.  They mature from the base upward as the wand grows, so as the season progresses the plant keeps making new flowers over a long time period while lower down fruits mature from the older flowers and release seeds. The entire reproductive cycle occurs all at once.

Seen from the side,  the flower looks like a tiny vase.  The upper rim of the vase is lined on the inside with five pollen-producing anthers mixed with fuzz.   The pollen-receptive style rises straight up from the vase floor. As the style rises it passes through the ring of fuzz and anthers which cover the tip of the style (the stigma) with pollen. That pollen germinates and completes the sexual cycle, all contained within the same flower.  No need for the birds and the bees.

samolus above green1

Style and stigma with self-pollen germinating.

That last statement is maybe a little over-stated.  Despite the self-pollination, bees and butterflies do visit the flowers.  Perhaps they bring a little outside pollen just to shuffle the genetic deck a bit.

There’s one more weird thing.   On the outside of the flower at the base, there is a donut of glistening wet material around the “bottom of the vase” surrounding the point where the flower stalk is attached.   A mystery.  Can’t imagine the shimmering gel attracts or feeds pollinators who could not get at it down and outside.    I suspect it is “flypaper” to prevent little crawling insects from bothering the blossom.


Sticky ring around the base of the flower


Posted by on April 3, 2020 in Samolus, Uncategorized


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Bladderworts High and Dry Where Bladders Don’t Belong

Utricularia cornuta

(A utricle is a bladder. Cornuta means horned, referring to the spur on the flower.)


ut corn 2

Horned Bladderwort by John Bradford.

Many wildflower enthusiasts are familiar with Bladderworts, species of Utricularia.    Utricularias are generally thought of as aquatic carnivorous plants dangling microscopic suction traps in the water.  The traps have trigger hairs and a trap door. When a minute swimming arthropod bumps the trigger, the trap sucks the victim in for lunch. That is documented richly on the Internet so no need for more here.

What has been interesting me this week is Utricularia growing in moist sand, often by the thousands in drifts of yellow.    Any questions? Question 1:  What pollinates a hundred thousand bright yellow blossoms all glorious at once in a couple acres?  That’s a blog for another day.


Question two is the topic for today:  How can an aquatic water-filled bladder catch water-borne prey while stuck in sand?  There has to be more to the story. There is, some of it well known, some mysterious.   As the pundits say, “let’s unpack it.”

First of all, don’t the plants root in the sand? No—Utricularia has no roots, although we will soon see leaf-ish structures functioning much like roots.

But let’s stay above ground a moment.   Plants typically need to photosynthesize, and that is a job for leaves.  But where are the photosynthetic leaves?  The plants look like a bare stalk with a flower out of focus on top.


utricularia cornuta snorkel stems 1

Vertical pins rise from the leafy mesh below the surface.

Just below the soil surface stringy leafy segments form a horizontal mesh, think of a smashed plate of spaghetti.  From that mesh millions of pin-sized segments rise vertically from the soil into the light of day.  The collective surface area of countless pins is substantial, like the microvilli in an intestine. They are green or partly red (sunscreen? damage?) and probably allow for photosynthesis, and conceivably help aerate the leafy portions below the surface, especially during flooding.    Room for research here!

A growing literature is revealing the idea of the trap feeding the plant by catching and digesting prey as simplistic.   The traps seem to be micro-ecosystems unto themselves.  CLICK

Trap-dwellers include microscopic protists, such as ciliates, bacteria, fungi, algae, and so-called bluegreen “algae.” Bluegreen “algae” are photosynthetic cyanobacteria often able to “fix nitrogen,” that is, convert atmospheric nitrogen to fertilizer.

The microbes manufacture nitrogen fertilizer inside the trap, you say?   Isn’t the main point of the carnivorous plant to obtain nitrogen from breaking down the insect victims? And photosynthetic bacteria inside the trap provide the same benefit without bloodshed?   Yes, if not studied adequately yet.

OK then, nitrogen-fixing cyanobacteria live inside the trap, possibly contributing to the plant’s nitrogen nutrition, what about outside the trap?   Not a new idea.  Botanists have recorded cyanobacteria clinging to the outsides of traps in the water.

So now think about that comparatively dry meadow of sand-dwelling utricularias.   Could  cyanobacteria in the sand be enriching the soil, maybe replacing the need for aquatic bug-catchery?

A close look at a population of Utricularia on “dry” land shows them mostly to rise from a thin surface carpet of periphyton, although not always, and there’s more to the picture.  Under the Utricularia is a blue-green living layer a fraction of an inch under the ground surface.   It looks like a miniature seam of coal.

utricularia gtreen band

A living blue-green seam in the soil

With room for more data (!), I suspect the land-living Utricularia is deriving nitrogen and possibly additional nutrition from the subsurface blue-green layer.  A look at that layer with a microscope shows it to consist in large part of, you guessed it, cyanobacteria.

utricularia cysnobacteria3crop

Cyanobacteria from the blue-green layer at the base of a Utricularia.

The plants form a thick brushlike mass  of rootlike leaves usually just below the green layer, or sometimes branching directly into it too.   The false roots can have traps, which exist to absorb nitrogen.   But who said it has to come from within?  Traps bathed in nitrogen fixed by a living soil layer of Cyanobacteria might as well absorb it from the outside as well.



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Sweet Shaggytufts

Stenandrium dulce

(Stenandrium means narrow anthers.  Dulce means sweet, probably in reference to the flowers although I detected no fragrance today.)

Acanthaceae, the Acanthus Family

For a variety of reasons I’ve let the blog lapse in recent months.  But here we are with isolation time for  nature.  So today I took to the Covid-free swamps to re-find a large population of Sphagnum to help with a friend’s research effort.   Plans take odd turns.   Out of the shrubbery scampered a big mother feral hog with cute baby(ies) and stood her ground in the path making grumpy snorty sounds, so I headed in a different direction, passing Sweet Shaggytufts during my craven retreat.   Now that’s a pretty species you don’t see every day, or every decade.

Stenandrium plant

We live near its northern limit, in Georgia, from which the plant extends southward to Chile.   Ask three observers what the natural habitat is,  and you will get three different answers.  It is one of the several species occurring locally that live like toads…starting out in water and ending up high and dry, often very dry.  Despite being semi-“aquatic” Stenandrium turns up on hot sun-baked sand, such as it did today, even in deserts and similar circumstances.  It spans both extremes, which is not unusual in South Florida.  Additional amphibians coming to mind include Brookweed (Samolus ebracteatus),  Hornwort (Mitreola petiolata), Small Butterwort (Pinguicula pumila),  and Oakleaf Fleabane (Erigeron quercifolius).

Stenandrium forms rosettes flat on the ground, often lots of rosettes, apparently from self-seeding.   It likes open space with no competitors and reportedly can  maintain its social distance by making natural herbicides.

stenadrium flower oblique

Today’s flower is a member of the large family Acanthaceae where the vast majority of species have microscopic pointy crystal-like structures in their leaves, called cystoliths.   Nobody knows what cystoliths are good for, although discouraging herbivores is a distinct possibility.  Stenandrium is in the small branch of the family without cystoliths, and (to speculate shamelessly) I wonder if the absence of cystoliths allows it to host the Definite Checkerspot Butterfly larva.  Perhaps the missing cystoliths force the  need for protection using the insect-feeding deterrent called benzoxazine. (Many caterpillars have the ability to tolerate and sequester toxins from the host plant.)  Don’t eat the weeds.

Even in 2020 what pollinates those pretty pink flowers is unknown.    Birds, wasps. and bees do not fit.  Moths are possible.  Butterflies seem most likely, and it would be fun to sit in the Shaggytuft patch awhile and see what flutters along.  I might just try that…although waiting for pollinators requires more patience than fishing.  Neither fish nor butterflies care about your timeframe.


Posted by on March 22, 2020 in Stenandrium, Uncategorized


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