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Peelbark St. Johnswort, Friend of the Fish

Hypericum fasciculatum

(Hyper-means above, and -icum comes from the same root as icon, above the icon, referring to the historical use of some species to adorn religious icons.  A fascicle is a bunch, such as a cluster of leaves.)

Clusiaceae

 

St. Johnsworts are many…around  500 species, 50-ish in the U.S.,  around 30 in Florida.   They are well known for bioactive contents, photosensitizing the skin of human and beast after consumption, locoweeds, and medicinal uses, especially to fight depression.  These things are all over the internet, and therefore of no new interest here.  More fun to go into less-documented aspects of Peelbark St. Johsnwort, Hypericum fasciculatum.

hyp fas bush

PBSJW.  Today’s pictures all by John Bradford.

So then, first, why “peelbark”?   Hypericum fasciculatum is mostly a species of seasonally inundated marshes…you might say “Hypericum marshes”…and of wet shores.   It spends much of its time up to its knees in water.   Seasonally flooded plants have a problem: ventilating their roots during highwater times.   Want another seasonally inundated plant with similar peeling spongy bark?  Bald Cypress knee bark resembles Peelbark St. Johnswort.   Those porous barks no doubt aerate the above-water regions. in my opinion the exposure in Bald Cypress sustains the living phloem just under (actually part of)  the bark.  In the St. Johnswort the peeling bark perhaps likewise feeds the phloem, and possibly ventilates the roots which have two special adaptations of their own.

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The first special adaptation is the formation of “adventitious” (on the stem) roots near the high water level.  This tendency has served during the dry months as a marker of erstwhile high water limits.

The second special root adaptation is a series of air channels (aerenchyma). Botanists who have studied similar roots in similar species have found the channels to help maintain optimal levels of the airborne hormone ethylene.

Why would an aquatic plant with unlimited water have narrow needlelike leaves resembling a dryland conifer?   It looks like a desert plant.  So does its marshland neighbor corkwood, Stillingia aquatica.  One  answer is probably that semi-impaired suffocating roots are unable to service large broad leaves well, and a second reason for skinny “desert”  leaves seems to be those challenging months when the shrub is high and dry.

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Here is a fishy mystery to ponder.  Why do Hypericum fasciculatum plants in bodies of water having fish manage a stronger seedset than those in fish-free habitats?  No. the answer is not “fish manure fertilizer.” Sometimes ecological relationships are fun to unravel, as UF ecologist T.M. Knight and collaborators did in 2005.   Fish eat dragonfly larvae.  Dragonflies eat bees and things.  Bees and things pollinate PBSJW.  So no fish =  many dragonflies = scarce pollinators. If fish abound, however, so do the pollinators and the seeds.

 
 

Rustweed – Three Weird Secrets

Polypremum procumbens

(Polypremum loosely translates as many-branched,  and procumbens means “lies down” without rooting from the stems)

Tetrachondraceae

 

Rustweed is a curious little thing.   Merely figuring out its relationships was a botanical head-scratcher for a couple centuries until DNA came along to solve all mysteries.  It lives on sun-baked sandy surfaces from Florida to Mexico and to the northeastern U.S., very abundant around Palm Beach County.  Branching is Y-shaped, and the paired leaves look like little sawtooth daggers.

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Today’s non-microscope and non-butterfly pictures by John Bradford.

The first of three Polypremum oddities is that the plants transform from leafy green to rusty orange-brown at times of extreme sun exposure or drought.   They are not dying…merely getting a tan.   Do they go back from rusty to light green?  I don’t think so.   Somebody ought to conduct a comparative study on their performances and tolerances in the two phases.  Do the rusty plants thrive under stresses green ones can’t handle? Do the green ones grow faster under favorable conditions?

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A second oddity is microscopic and beyond my photographic ability, so below is a drawing from a 19th Century German treatise on plant hairs.

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The leaves have on their undersides microscopic “glands” with a beautiful structure and recessed into the leaf surface.  What do they do?  I’ve been wondering that since the 80s.  We often think of glands on leaves as producing nectar to favor defensive ants.   Not in this case.   To make a varnish to protect the leaf?  Naw, wrong placement.  To excrete excess salt?  I doubt it, wrong habitat.  Drain excess water?   Water-secreting structures are common, but these have the wrong structure and placement, rejected. You know what they look like to me?  The complex structures on Tillandsia leaves that function in part to take in water in a stressfully dry habitat.

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Did somebody say stressfully dry habitat?  You know, like Rustweed-inhabited sand in a Florida scrub.   Speaking speculatively, I’m guessing those little “glands” help take in precious water from rain, mist, and dew out on those parched sands.  Might be tough to test and prove without sophisticated gear, although weed scientists have shown plant hairs on other species to take up herbicides in water.  Things that matter get studied.  One quick test that might suggest or nix water intake would be to see if the leaves gain weight upon foliar water exposure, with no water applied to the root.

Polypremum procumbensTWO

With a tan

Oddity number 3  requires a speedy pre-lesson.   In a flowering plant’s sexual cycle, to make a long story short, the pollen grain sprouts a tube called the pollen tube, and the pollen tube delivers the sperm to the egg inside the future seed.  The textbooks tell us the pollen grain with its seminal cargo arrives from another plant thanks to the birds and bees.  Textbooks lie.

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Dainty Sulfur meets Rustweed, contributed by John Lampkin

Suppose you are a lone Rustweed, bereft of that “another plant,” established by a wind-blown seed on some remote sandy patch to colonize.  Rustweed has colonized  Hawaii, Guam, and Palau.    How can it reproduce all alone and isolated?   Not a problem,  as iconic botanists Asa Grapy and John Torrey noted back in 1841.  They found Polypremum to germinate its pollen tubes within the flower that made them, no need for pesky birds and bees.   That germinated pollen (i.e.  with pollen tube) takes care of fertilization without ever leaving its home flower.  As far as I can tell, nobody has re-noticed or mentioned it since, although various forms of self-pollination are not rare.   That 179-year assertion by Torrey and Gray had to be checked, what if they were wrong OMG!!!, so I brought some Polypremum  home today for  a look.  They were correct, the pollen trapped inside the flowers is still sporting pollen tubes rarin’ to go.

Polypremum pollen tube

Pollen with its pollen tube hanging around today inside the flower that made it.

 
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Posted by on June 19, 2020 in Polypremum, Uncategorized

 

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Meat-in-a-Mist

Passiflora foetida (Love in a Mist)

(Foetida means smelly.)

Passifloraceae, the Passionflower Family

Want to try a creepy adventure?  This morning I got up at dawn to beat the thunderstorms, which have not come.  Plunged into the murky mists in an inundated Hypericum marsh to tend to a little botanical business.  In over your knees in the morning twilight among reeds, tussocks, fallen logs, bird groans, croaking frogs, and wil-o-the-wisps, it is eerie to hear “things” swimming.  I mean what swamp dwellers splash when they swim!?   The imagination runs wild.  Critters  splash into the black water as you approach.   To the neurotic, a frog plop sounds like a hippo.    Any pythons in PB County? Do Cottonmouths splash when they flop in from a low branch?  Not so spooky are the Zebra Longwing Butterflies out in force today, interestingly going about their flutter duties low in the foliage. Zebra Longwings bring to mind Passionvines, the topic with such a long lead-in.

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By John Bradford

Today’s blog rests on the shoulders of titans.   Biologist Dr. Walter Bien suggested the topic and sent info.  He and John Bradford took the photos.  Passiflora foetida, native to South America, is introduced and weedy all around the hot-climate world, including here.    If we must be invaded the intruder might as well be beautiful, and curious.

The pretty flower looks like many other passionflowers.  The fruit suggests a red cherry, helping to explain its global conquest with the help of birds.   Today’s focus is on the net wrapped around the fruit, inspiring the name “Love-in-a-Mist.”  The mist is made of bracts wrapping round from beneath the flower.

Now any fool can guess the net protects delicacies within. Demonstrably so.  If you want to keep the bad guys out, a little toxin can be useful.   Could offing pests be a first step toward carnivory?   If you’re going to kill’em you might as well eat’em.  Granny salvaged roadkill after all.

passiflora bracts wb

By Walter Bien

As Dr. Bien related, the net is protocarnivorous.  Glands on it secrete a compound called passifloricin and sticky mucilage to trap insects.  Passifloricin is a lactone  a broad family of cyclic molecules often bioactive and in many fragrant essential oils.  Passifloricin kills microscopic protists and undoubtedly also small insects.  Going beyond mere defense, the secretions have protein-digesting enzymes.  Drumroll please! That ability is characteristic of carnivorous plants.

[assifora fruit

Walter Bien

Tests on Passiflora foetida by biologist T. Radhamani and collaborators in the 90s showed the substances to digest dead ants into amino acids, the building blocks of proteins.  They showed further a traceable amino acid smeared on the bracts to wind up in the seeds.  In short they demonstrated slaughtering the fresh meat, processing it, and recycling the stolen nutrients.

Please don’t go push poor little buggies into the web of death, but it might be interesting to peek in with a magnifying class.

 
 

Bartram’s Rose-Gentian

Sabatia decandra (S. bartramii)

(Sabatia honors Liberato Sabbati,  an Italian botanist.  Decandra refers to 10 stamens. William Bartram was a brilliant 18th Century plant explorer in Florida and other states,  artist, and eloquent writer whose (father’s) garden you can still visit in Philadelphia.)

Gentianaceae

Sa atia drawing

By William Bartram

Sometimes all it takes is good looks.  Try to find a more magnificent wildflower than this.  Shocking pink with a yellow star!   Anyone need a logo?  What pollinator could resist? This floral celebrity has  a web presence bigger than Beyonce!…with the same info over and over, so the trick here is to find something new.  Will do.

Sabatia fem ale phase JB

By John Bradford

Sabatia is a genus well represented in Florida by a dozen species, all of them pretty, generally not cultivated however, probably due to finicky habitat requirements. Today’s species beautifies wetlands in the Southeastern corner of the U.S. Descriptions call it a biennial, and I’m not saying it isn’t, but I’m not sure that is the whole truth and nothing but the truth.

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It looks like a biennial in the sense that it rises from a basal rosette like a standard backyard weed biennial.   However,  the species grows in seasonally inundated places so if the rosette sits around a year, it is sitting underwater half the year.  I think the rosette and the flowering top can rise in the same year.  Another wet-dry plant with a similar slightly succulent rosette is Brookweed, Samolus ebracteatus.

sabatia bud

The bud is a perfect frame for a web.  Many of the buds are inhabited.  I wonder if that helps protect the flower.

I promised something new and here it is.   Species of Sabatia, and dramatically S. decandra, have a system to force cross-pollination, first functioning as male then  later becoming female. As the flower opens, the pollen-producing (male) stamens get busy dusting pollen onto floral visitors.   At the same time, the pollen-receptive (female) stigma is twisted and flattened horizontally as removed from the pollinator action as possible.

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Male phase…the female stigma and style are flattened out of the way on the left.

Sabatia anthres

Stamens…male phase

After the pollen release time, the stamens commence senescence.  Then the patient stigma untwists, rises upright, and takes on a Y-shape to celebrate pollen-reception time as the stamens fall apart..

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Female phase…the stigma now upright looking like a Y, the stamens falling away.

 
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Posted by on May 22, 2020 in Sabatia decandra, Uncategorized

 

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Water Hyssops

Bacopa monnieri and Bacopa caroliniana

Hyssop is an ancient name, including in the Bible, applied to any of many fragrant herbs.   Bacopa comes from an indigenous South American name. Louis-Guillaume Le Monnier (1717-1799) was a French scientist whose interests extended to botany.)

Plantaginaceae

Members of the genus Bacopa are easy to overlook, and in wet muddy habitats. Most passers by probably step on them.  The flowers are pretty although not eye-popping.   Despite their unassuming modesty, bacopas are botanical wack-a-moles popping up in disparate connections. Four species live in Florida, two native (including B. caroliniana with blue flowers), one (B. monnieri ) debatably indigenous, and one introduced.

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B. caroliniana by John Bradford.

Aquanauts

Bacopas are among an intriguing clique of species able to grow underwater like seaweeds yet also happy high and dry.  Pretty handy for Florida habitats submerged part of the year and sun-baked mud the rest of the year.  The underwater ability is why you can buy them as aquarium plants, and that in turn is in part probably why today’s species are invasive exotics in other lands. A second probable contributing factor to their global spread is via cultivation as ancient medicines.  Bacopa monnieri is so widespread  worldwide it is hard to know its original “nativity.”  It is an invasive problem species in Hawaii, the Cayman Islands, and in eastern Asia.  Bacopa caroliniana has made it to South Korea.

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Bacopa monnieri by John Bradford.

Green Lanterns

Taiwanese researchers infused gold nanoparticles into Bacopa caroliniana, and it glowed like a botanical LED.  That ability could be harnessed.   Big thinkers thought, well, it that works in a sprawling water weed, onward to  living street lights?   You saw it here first.

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Friend of the White Peacock

My wife Donna and I have spent Corona-time over-tending our backyard butterfly garden and its little villagers. Among the gorgeous visitors  have suddenly appeared a profusion of White Peacock butterflies.   They are broad in their floral tastes, yet picky about their larval host plants, in fact, limited mostly to species of Bacopa and Phyla (Fogfruit, aka Frogfruit).   Behind our house is a broad canal, at this moment almost dry, the exposed mud with big patches of Bacopa.   I’d go out now and try to photo a Peacock caterpillar but it is raining.

Lemony Fresh Nerve Poison

The name Lemon Bacopa fits Bacopa caroliniana.  Empowered with that knowledge, you will never struggle to identify it…just scratch and sniff.  Ahhhh, a cleansing whiff of lemon.  No trip to the mudflats is complete without it.  As with most plant stinkiness, we’re talking herbivore deterrence. A 2019 study showed it to have a similar mode of nerve-poison action against insects as commercial organophosphate insecticides, such as Malathion. Knowing that, no thanks on Bacopa medications.  (Please don’t eat the wildflowers.)  Fact is, Bacopas are green chemical factories and not everything in them is harmless.

Don’t Forget This

Want a medicinal plant?   Go outside and pick a specimen, bring it in and Google it.  Somebody somewhere has applied it for something.   That goes double for fragrant species.   So why delve into the usually boring realm of old plant uses here and now?  Because Bacopas, especially B. monnieri, are monsters of medicinal applications worldwide.  Always interesting when multiple separate human cultures find similar uses for a given plant.  Here is just one example of B. monnieri’s fan mail from hundreds:

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Most of the historical uses center on the nervous system.   Neurological (and additional) effects have brought B. monnieri into the fold of modern medicinal interest. Many parties feel the herb and its extracts enhance cognition, and may even help in Alzheimers, which could be true with the caveat that the world of plant-dervied medicines tends to be  very very optimistic.  Really, it had me with host plant for White Peacocks.

white peacock on samolus ebracteatus

 
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Posted by on May 15, 2020 in bacopa, Uncategorized

 

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White Lobelia and Plunger Pollination

Lobelia paludosa

(M. de L’Obel was a Flemish herbalist. Paludosa means swampy.)

Campanulaceae (Lobeliaceae)

Oh so pretty,  White Lobelia is wetland wildflower worth soggy sneakers.   Those curvaceously symmetrical white flowers look like the work of a marble sculptor…or maybe a plumber, read on.   This is one of many Florida lobelias, mostly north of our region.  Lobelia overall has 400 species almost worldwide.  Gardeners love lobelias as commercial ornamentals.  Native plant enthusiasts know them as diversely colored wildflowers, especially in wet habitats.  Smokers may know them too:  Lobelia inflata, Indian Tobacco,  and some additional Lobelia species (as well as some non-lobelias) give forth the alkaloid lobeline used to wean smokers off of nicotine and for other historical medicinal “benefits.”  (Warning…alkaloids are dangerous.  Do not eat, smoke, or otherwise ingest the wildflowers. Lobeline has morbid toxic effects, including potentially death.)

lobelia flower

See the slit?  The black unit is the tip of the stamen tube.

You can always recognize a Lobelia by a slit running the length of the flower tube.   More on that in a moment.

Lobelias have a crafty means of pollination that protects pollen from the elements and from pollen thieves, dispensing it gingerly onto the floral visitor only as needed.   To understand the pollen dispenser we must understand the flower.

It is bilaterally symmetrical with a tube made of petals.   The top of the petal tube has that weird slit you already know about.  On either side of the slit the top petals are curled back seemingly to guide the visitor to the business parts of the flower near the slit.  Now for the business parts:

The stamens are joined edge to edge to form a hollow stamen tube inside the petal tube.   The stamen tube bends upward and can rise forth through the slit.  The outer tip of the stamen tube is made of five anthers likewise joined edge to edge, releasing their pollen to the inside of the stamen tube.

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You with me?  The anthers form a tube with loose pollen inside toward the outer end.

lobelia slit

Slit and tube poking up through it. This flower is in the post-plunger female phase.  The stigma has popped to the left out of the end of the stamen tube. No more dispensing pollen…now it time to receive some from a different flower.

Now comes the female component…the style rises through the stamen tube with a broad stigma at its tip.  The rising stigma acts like a plunger pushing pollen out the end of the stamen tube.

lobelia paludosa stigma 1

The anther tube (right) sliced open and the style and stigma bent up for visibility (left).

lobelia paludosa anther column close 1

Tip of the stamen tube isolated. A little bit of yellow pollen visible to the left.

At this point the stigma is not receptive to pollination.  That comes later after it has pushed all the way out of the stamen tube.   Back up a moment and consider the stigma in its plunger phase still inside the anther tube:

A bee comes along and probes the flower for nectar.  The tip of the stamen tube dispenses a dose of pollen onto the bee, like toothpaste dispensed out from the tip of its tube onto a toothbrush.  (See the diagram above.) Although I can’t prove it, it seems the bee pushing on the tip of the stamen tube and also maybe on the tube more basally helps squeeze the pollen out by narrowing the tube and/or by forcing the tube to shorten a little while the style-stigma plunger inside stays firm.  Think of wearing a loose long sleeve shirt with the cuff exactly at your wrist.  If you push on the shirtsleeve it will kink, fold, or narrow a bit so a bit of your wrist becomes exposed.   This can be simulated with the tip of your finger posing as a pushy bee.   Pollen release “on demand.”

 
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Posted by on May 8, 2020 in Lobelia paludosa, Uncategorized

 

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Florida Swamp-Privet

Forestiera segregata

(LeForestier is a personal name. Segregata refers to the separate male and female plants.)

Oleaceae (The Olive Family)

Years ago I had a horticulturist friend whose son had a backyard clubhouse.  The boy posted a sign over the door saying Privet Club.  I complimented my friend on imbuing his son with such horticultural enthusiasm.  He replied, “naw, he just can’t spell private.”

Forestiera segregata is a shrub distributed in the Caribbean and in and near Florida,  it is abundant in our area, willing to grow happily and quickly in diverse habitats,  shaded and sunny, best moist but ok with dry, iand alkaline places are fine.   Broad tolerances are part of the key to its place in native landscaping.   In Florida the natural distribution is mostly near the coasts, not much inland.

forestiera

Blue olived by John Bradford.

Swamp-Privet has separate male and female individuals, that is, it is dioecious (dye-EE-shus). Only a small minority of plants are, and far more unusual is the combination of dioecy and predominant insect pollination as opposed to wind.   You’d have to work awhile to make a short list of Florida species with that combination.  Wind-pollinated plants make a lot of pollen, so separating the male pollen-making and female pollen-receiving plants avoids plants being overwhelmed with their own pollen.  Implicit in that, separating male and female plants forces cross-pollination.   Why can social sexual distancing be a disadvantage in most insect-pollinated species?  Wind carries pollen long distances, but insects not necessarily.  Separate male and female plants may be farther apart than the usual insect delivery-trip.   All couched in usually, maybe, and often of course.

The fruits look like tiny blue olives, which may be the result of their membership in the Olive Family.   The fake olives taste like rat poison, at least to a human.   Maybe so to bird distributors too, as it seems the fruits persist on the shrubs uneaten like my granddaughter’s broccoli, much longer than apparently more palatable fruits, oh say, blueberries or mulberries.  Observers have suggested that birds shun yucky fruits until more sugary options are depleted, then the birds turn grudgingly  to the nasty fruits in which the plant invests minimal precious sugar.   Cheap fruits for desperate birds?  Beggars can’t be choosers.

The beauty of the fruits exceeds the flavor, and in other Forestiera species ancient cultures smooshed the fruits with white clay to make cool blue body paint.  The medical practitioners in such cultures harnessed the repulsive little olives as an emetic (something that induces vomiting).   And speaking of useful Forestiera, the lightweight straight branches are good arrow shafts.    In dry habitats forestieras are valued signs of “dig here for water.”

 
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Posted by on May 1, 2020 in Forestiera, Uncategorized

 

Smart Dollarweeds Walk Away from Trouble When They Can

Hydrocotyle varied species (Dollarweeds)

Apiaceae (Carrot Family)

Marsh plants are fascinating because their sprawling patches can be single clones, one big individual all laced together by rhizomes,  one gigantic plant, and that breeds interesting questions, such as when patches collide…is it individual plant vs. individual plant,  planto-a-planto? (Not for today.)  When a patch of Dollarweed, and this is not hypothetical, differs genetically from a different patch of Dollarweed when the two are in different places with different conditions, what is the basis for that genetic difference? Quick localized genetic adaptation, instant evolution,  causing differentiation of originally identical starts? Or did two genetically different seeds each wind up thriving where their own unique genetic palette was optimal?  Or neither?   (Not for today.)  What is for today is botanical braniac behavior by  Dollarweed, a prospect raised most saliently by ecologists J. Evans and M. Cain in 1995.

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Today’s photos by John Bradford.

A clonal patch resembles a giant amoeba…it can expand this way and that depending on circumstances;  some portions stumble into bad areas and fizzle, while other portions expand into favorable zones and thrive, branch, and expand.   Nothing amazing there.   Anyone who has faced  tree roots in a sewer pipe  may now bow to the Roto-Rooter  Representative.

Now back to amoeba business.  A slime mold is much like an amoeba as big as your hand.    The “plants have intelligence” enthusiasts tout the mold’s ability to “solve” a maze with food at the end.  SLITHER HERE  Well sorta…it slithers hither and thither and then dies out wherever there is no food, thus producing ultimately one surviving strand leading to the oatmeal…biologically amazing and complex, but not “solving” the maze like a slimy little Hercule Poirot.

Hydrcotyle has its own smart trick.  Remember the concern above about expanding wastefully into unfavorable places?   Wouldn’t it be nice to avoid evil before stepping into it?   Yes!  A clone of Hydrocotyle can steer its rhizome growth clear of competing grass clumps.   A skeptic might ask, “is it merely that the grass roots block the Hydrocotyle rhizome?”  Naw, they checked on that.   The rhizome veers off safely before contact like I alter course (usually) before blundering into a stinky crocodile-infested malarial miasma on my explorer map.

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Now we all agree prescient side-stepping is  fancy for a lawn weed.  Complex and responsive yes,  but “woo-woo OMG! don’t hurt the sentient plants,” no.  Although the behavior is not explained, it is easy to suggest mundane ways the Dollarweed avoids trouble.  Evans and Cain suggested perhaps it senses the area of nutrient-depletion surrounding the grass roots, or maybe root secretions are the no trespassing signs.  Experimenters will nail it down if that has not occurred already.  What makes me more curious is, what additional marshland green amoebas have radar,  or engage in other cool behaviors?

 
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Posted by on April 24, 2020 in Hydrcotyle, Uncategorized

 

Gratiola – Herb of Grace

Gratiola ramosa

(Gratiola means “petite gratifying” (flower), and ramosa means branchy.)

Plantaginaceae

Verboden masthead

Masthead on Dr. Garleanne’s Gratiola article.

Some species are a little mysterious.   Gratiola is a lovely wetland wildflower you have to stop and bend over to enjoy.   Like Rodney Dangerfield, it gets no respect, and no botanical attention. The literature on these plants is a black hole.    Gratiola resembles a set of additional short-statured more or less related wetland species easily confused with each other:  Axil-Flower (Mecardonia), (False-Pimpernels, species of Lindernia), and Bacopa species, sometimes also called “herbs of grace). They can be mildly confusing to sort out…not the time and place.   With Covid dominating everything, it is tough to get out and botanize.   Almost all natural areas are closed.   Near my home is a small unnamed unofficial wetland I’ve been haunting socially distanced, befriending Gratiola.

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Gratiola ramosa by John Bradford. Petals whote, and yellow with stripes in the tube.

The only meaty account of Gratiola I can find is fun to read, although in Dutch.  I read Dutch fluently (thanks to Google Translator).   Speaking of botany under duress, the account was written in the Netherlands in 1947, based on explorations in 1946.  The Netherlands in 1946? Wow.  And it makes me feel good that back then somebody,  Dr. A. J. M. Garjeanne, went out and enjoyed Gratiola too.  We had a parallel experience some 70 years and an ocean apart, and we noticed some of the same things.

gRATIOLA RAMOSA BUD

The bud by JB.

  1. Dr. Garjeanne asserts: “Even in the still closed flower, the dust is already spreading out.”

The dust is the pollen…in short, the flowers release pollen before they open. That could indicate self-pollination, or merely that the flowers function as “male” before turning female.  That Dr. Garjeanne had trouble finding immature and mature fruits put the kybosh on self-pollination, so he preferred the latter interpretation of male-first.   In our area Gratiola makes fruits.

  1. In the words of Dr. G: “I can assure you that the stigmas on my specimens  …  are not irritable. In the few hundred flowers that I looked at, the stigmas were always on top of each other, and touch with a pencil, a needle and a pen did not change that. The stigmas  do separate from each other by gentle lateral pressure (as is done by children with snapdragons).”

This requires some explanation and is interesting.   In our local species the style and stigma (the pollen-receptive organ) looks like a garden hoe, the handle of the hoe being the style and the blade of the hoe being the stigma.  Dr. Garjeanne perceived the hoe blade to be two flaps pressed tightly together, like two pages in a book.  His illustration is below.   I have tried to separate them under a microscope and fail.  Also like Dr. G., I have poked and prodded them to find no irritability (motion in response to physical contact).

style and stigma Dr. G

Dr. G’s picture of the large basal ovary, and the style and stigma toward the top. See the hoe?

 

Stigma Dr. G

Dr. Garjeanne’s 1947 picture of the stigma. He drew it with two flaps.

Gratiola style

Hoe-shaped style and stigma yesterday. I cannot discern two flaps.

  1. To quote Dr. G: “We have already said that insect visits to Gratiola are so infrequent that I have not observed any visits, although in two cases I have found thrips in a flower (one in each flower).”

Me too.  I have watched eagerly for the bees presumed to pollinate Gratiola and find it hard to catch pollinators in the act…but have caught on a GoPro footage of a small hymenopteran visiting two flowers and diving in fully fr a several seconds.

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I’m sure they visit, but to agree with Dr G., not during my peeping, and guess what, I too find thrips in the blossoms.   Thrips pollinate some flowers, but I kinda doubt they are important pollinators in Gratiola. Leave that to the bees lured by lots of nectar even if not when  Dr. G or I watch. Thrips eat pollen, and I wonder if the complex structure of the Gratiola flowers protects pollen from thrips, as well as from other thieves.

Gratiola thrips

Yep—thrips

If you look into the mouth of the flower you see a tangle of hairs you might say on the “roof,” with the flat face of that hoe-shaped stigma blocking the tunnel.  The handle of the “hoe” extends back into the flower along the “roof,” and the blade partially blocks passage deep where the treasured nectar and pollen hide.    The  two anthers resides just interior to the hoe-blade style…the blade effectively shields the pollen, which seems also to hide behind the mass of hairs on the roof of the tube.

Gratiola downthroat3

Lookin down the throat…there’s that big flat stigma blocking the tunnel.

 

There is a second purpose for the mass of hair according to other observers. Those sneaky private bees allegedly use the hairs as a foothold as they push deeply into the flower tube.  Doing that would rub their bellies across the pollen-depositing anthers as well as against that weird hoe-blade pollen-receiving stigma.

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Gratiola stamens in fuzz1

Open flower. Stigma at the center with two anthers just behind (to the left).

 
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Posted by on April 17, 2020 in Gratiola, Uncategorized

 

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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.

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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.

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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.

 
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Posted by on April 10, 2020 in Uncategorized

 
 
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