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Sea-Oats

Uniola paniculata

Poaceae, the Grass Family


Not many plants out-beauty sea-oats with its fancy flat spikelets aflutter in the ocean breeze.  Location location location. Despite its conspicuousness, and its value for stabilizing coastal dunes naturally or via cultivation, the species has mysteries.  And it is not really an oat.

Sea-oats. All photos today by John Bradford.

One mystery is, given that Uniola be cultivated inland, why in the wild is the grass almost always restricted to ocean dune, from the high water line to the windward faces or crests of  dunes?  Inland from those places, it disappears abruptly.

One answer is probably competition.   Sea-oats are so specialized for competing on ocean-facing dunes with salt, intense drying, blazing sun, stingy nutrients, relentless abrasive wind, storms, and shifting sands, it may not compete effectively elsewhere.  Fun fact: the roots reportedly can go down 40 feet.

Sea-oats spikelet. Does it contain seeds?

Another sea-oats mystery is reproduction and dispersal.  It makes seeds, but in some places few to none, and often makes empty spikelets.   And when there are seeds, wild mice and other creatures gobble them up.   The big flat spikelets probably blow across the sand to prevent loose seeds from premature burial at the base of the mother plant.    The seed production is influenced by environmental conditions, being correlated with distance from the briny deep.  A big creepy rhizome system is a safeguard from waves and wind, and rhizome segments exposed by shifting sands break free, drift away, and resume existence on new shores.  This ability has served for planting sea-oats where its presence is desired.

Bitter panicum spikelets

Sea-oats has a frenemy called bitter panicum (Panicum amarum).  The two big grasses frequently occur together and have similar seashore distributions up the Eastern Seaboard and down around the Gulf of Mexico.  They are often more or less intermixed on the same beach sites, which raises the question of what ecological differences separate them?   There are some hints of ecological differentiation.   Bitter panicum has broader tastes:  marginally wider range, some “inland” presence (not much),  and less restriction to the windward faces and tops of dunes as sea-oats.  

Bitter panicum

Seems maybe bitter panicum is a little better at competing outside of the narrow sea-oats comfort zone, and sea-oats just a little better at competing in its special place.   They have subtly different nutritional characteristics, and probably have different fungal root associates.   Sea-oats is especially intolerant of waterlogged sand in contrast with bitter panicum extending into swales between dunes and into soggy marshy places.  Bitter panicum is a teeny bit more of a generalist and the “oats” a wee bit more specialist. But then again, the interactions between the two have never been studied so far as I can tell.

 
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Posted by on August 5, 2022 in Uncategorized

 

Asiatic Latherleaf

Colubrina asiatica

Rhamnaceae


Asiatic Latherleaf is a worldwide tropical coastal invader.   This climbing shrub-vine is an aggressive fast-growing pest from Vanuatu to Hobe Sound, Florida.   Its original home is lost to history, but undoubtedly in the Old World Tropics.

Aggressive Latherleaf at the inland edge of a mangrove stand, Hobe Sound, FL

In the Americas, it probably started out Jamaica in the 1850s,  where the plant was imported as a medicinal asset.  Latherleaf made it to the Keys in the 1930s,  to Miami, the Everglades and Jupiter Island in the 1950s and 60s,  and to Merritt Island no later than 2014.   Those northward steps might reflect Global Warming,  or alternatively may merely be the ripples in the pond spreading from that Jamaican introduction.  

Latherleaf by John Bradford

The species island-hops with ease, starting with the fruit capsule exploding to launch the seeds.  Those bits of reproductive shrapnel have a hollow space for flotation, and withstand multi-month (or more) ocean voyages.   They also can “lay low” buried in mud and sand.   Birds may help with dispersal by using the pebble-sized seeds as crop stones.  The sprawling shrubs can take over large areas by shading out and reportedly even poisoning competitors.    The only species able to survive under a Latherleaf stand is more Latherleaf.  The babies wait patiently in the deep shade of their parents while developing massive root systems, and then rise up when hurricanes create a gap.   

Flower and fruits, JB

The reproductive biology is mildly puzzling because Latherleaf flourishes far from any original pollinators, and has been observed  to be slim on insect visitors despite a big yellow “nectar disk” at the base of the flower.   Botanists have speculated that the flowers may be self-pollinating or even fertile without pollination.  Wind pollination has never been ruled out.   Also the branch tips root upon touching the ground, as do broken stem fragments.

The name Latherleaf comes from suds formed when the crushed leaves are stirred in water, giving it historical uses as a natural soap, shampoo, and massage lotion.   As is commonly the case with lathery plants, extracts are bioactive, with ancient uses as fish poison and in medicines.   The numerous drugs in the foliage may be on the strong side, given such uses as inducing abortions and expelling intestinal worms.   The presence of the species across the Pacific has been attributed speculatively to ancient seafarers taking it along as a portable Walgreens.

The name Colubrina comes from Latin for snake,  referring to the attractive snake-ish branches which have served on Sri Lanka for weaving mats.   The dark tight-grained wood is useful for small ornamental objects such as knife handles.

 
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Posted by on July 22, 2022 in Uncategorized

 

Is the American Bumblebee Buzzing Off?

Bombus pensylvanicus


A photo of a bumblebee on a flower.   Camera fun, no big deal, but this particular species is of special interest. 

You can distinguish the “American Bumblebee” from other Florida-occurring Bumblebee species  because the American Bumble has 12 segments in the antenna (good luck with that!), pollen sacs on its hind legs (vs. no sacs anywhere), and its “back” from the wing attachments to the abdomen is black, as opposed to yellow or mixed colors.

American BB: Pollen sac. Black back from shoulders to waist.

Why would a Bumblebee not have pollen-collecting sacs?   Those sac-free species are cheaters.  So-called Cuckoo Bumblebees, they’d rather hijack other Bumblebees’ nests rather than gather their own pollen.  Such not-so-busy bees are unusual in Florida,  one historical cheater here, Bombus variabilis,  may be extinct or nearly so in the U.S.,  surviving still in Tropical America.   A parasite needs a pollen-collecting host, and the host species have problems which brings us back to the American Bumblebee.

I’m not a Bumblebee!

The American Bumblebee has been in decline for decades.   How old and how severe is the problem?  Hard to say, because the data are skimpy.  After all, not many biologists study Bumblebee distributions, and it is tough to gather info over millions of square miles.  Despite holes in the knowledge, it seems the American Bumblebee and some others, but not all bumblebees,  are dwindling.  

What’s particularly odd about the American Bumblebee is that most of the decline has been in the northeastern portion of its historical range from Canada to Florida, Mexico,  to (a little) in California.   It is doing comparatively well in the southern and central states, while disappearing from the northeastern corner of its range.  Recent publications suggest about 20% range loss so far, mostly in and near New England.

There is no consensus on the reasons, especially because any explanation for the decline must take into account its geographic bias.   Searching Goggle turns up with differing degrees of emphasis “the usual suspects” with respect to decline in other living things.   In alphabetical order:

Climate change:

When a wife is murdered, detectives look first at the husband.  When an insect range changes, detectives look first at Global Warming.  But, although an indirect effect is obviously conceivable, it not easy to explain how a warming climate would wipe out a species in the coldest part of its range. So far, no evidence.

Neonicotinoid insecticides:

That the decline seems to have accelerated with the onset of heavy use of neonicotinoid insecticides is suspicious.  And neonicotinoids are prime suspects in related crimes such as honeybee Colony Collapse Disorder, migratory bird disorientation, and more.   But are neonicotinoids a special problem in the Northeast?  As the District Attorney may say to the detectives,  “suspicious, go get me more evidence.”

Parasites:

Bumblebees suffer from mites and microbial infections, most famously a fungus Nosema bombi.   It has been speculated strongly that a deadly strain Nosema invaded native Bumblebee populations from European Bumblebees imported for greenhouse pollination.  Notably, researchers have shown a high instance of the fungus in declining Bumblebee populations.   But association does not prove cause.  It could be that declining Bumblebees are weakened from some other root cause, making them more susceptible to infection.   Molecular studies have failed so far to find a special deadly Nosema associated with commercial bees.  But then again, microbes are many and we don’t know what we don’t know.

Shrinking Habitat:

American Bumblebees are largely meadow species, breeding in low grassy plants.  Shrink the meadows, shrink the BB populations.  Meadows may be a declining “thing.”  Just ask the butterflies!  Meadows don’t have much protection, as opposed to scrub, or wetlands, or old growth forest.  Protected meadows mature into woodlands.    Lots of meadows were roadsides and railroads, or hayfields, or fallow fields, or pastures, or margins around farmlands.   Changing agricultural practices and changing land-use patterns aren’t helping expand meadowy bumblebee habitat.   A changing agricultural practice is massive application of effective herbicides, such as Round-Up.  Many meadow species are “weeds,” and we’ve gotten effective at weed control.    Could it be that open, weedy, semi-neglected meadows have diminished especially in the Northeast?   Maybe so, given that a great deal of former farmland and lumbered land in and around New England has reverted to forest.   Fires that used to return forests to meadows are now better controlled.   Where do you build new subdivisions and big box stores?   Largely in existing open unprotected vacant space. One day meadow “weeds,” next day sprayed turf and parking lot.

So whodunit?   Nobody knows, or if they do, they have not brought other observers into agreement.    In Agatha Christie’s “Murder on the Orient Express” every suspect had a hand in it.   Or then again maybe Global Warming, germs, insecticides, weed control, and dwindling vacant lots are a bunch of red herrings.  Personally, my favorite culprit is habitat loss, but that’s no more than a guess.

 
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Posted by on July 15, 2022 in Uncategorized

 

Little seaweed, big discovery!

Mermaids’ Winecup

Acetabularia species

(ass-ah-tab-you-LAIR-ee-ah)

Greem Algae

Here’s a pretty life form encountered Wednesday growing on a seashell in the saltwater Intracoastal Waterway near Hobe Sound.   A charming little Green Alga called “Mermaids’ Wineglass’” although it would fit only a Thumbelina-mermaid, and it looks more like a martini glass.  But you get the picture.   I fancy it.

Wineglass on the half-shell.

Acetabularia isn’t just good looking.  It has brains too.  Back in the 1930s and onward, this little alga had a big role in genetics   It showed the nucleus to be the informational center of the cell.  (Genetic research sure has  come a long way since the 1930s!)   Back then it wasn’t exactly clear what part of the cell was the control center.  (Now they can use one gene in your spit to determine if you kissed the Blarneystone.)

Makes me want a martini!

Back in the pre-DNA era why did they choose Acetabularia to find the control center of the cell?  Because the entire plant is just one cell having  just one nucleus.   By cell standards, HUGE, and easy to grow,  plus easy to manipulate.  You can cut the stalk and cup off the base, graft on a new stem from a different individual, and watch it regrow a new cup on the top of the new stem.

That gave biologist Joachim Hämmerling a “Eureka” moment.  He conducted many experiments on Mermaids’s Wineglasses, but  one experiment says it all.   If you remove the stalk and cup of one species (call it the green species) and graft on the beheaded stem of a different species (call it the blue species),  when a new cup grows on top of the transplanted “blue” stem, is the new cup “green” or “blue”?  Answer, it is green, that is, the new cup conforms to the base, not to the new stem even though the new cup grows upon the new stem.   Something in that base, the nucleus, is directing development remotely, and that’s the nucleus.  Hammerling tried combining two nuclei in one plant and got a tweener.

To go one step further for any reader who likes biology,  if the nucleus (in the base) is able to direct formation of a matching cup (at the top) something must go through that transplanted stalk.  Like my computer Bluetoothed to my headphones.   That something passing from the nucleus through the stalk to the tippy top was RNA.  Yep, Acetabularia had a role in the discovery of RNA too.

 
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Posted by on July 8, 2022 in Uncategorized

 

Flower Benefits to Bees:  Nectar, Oil…and pollen for warning coloration?

Flower Benefits to Bees:  Nectar, Oil…and pollen for warning coloration?

Like to watch flower visitors?  I  do, although other folks may have more exciting hobbies.  A great flower for pollinator-watching is Carolina Redroot (Lachnanthes caroliana).  Everybody comes along:  butterflies, wasps, beetles, bees, and who knows what else.  Here’s a sampler from just today:

I’ve got warning colors!
Who’s your favorite Beatle?
Queen on the way
More warning coloration. Oh look—here comes a Duskywing
Landed safely

When it comes to beautiful bugs, why pick favorites?  But the visitors who piqued my biological curiosity today were bumblebees in connection with their warning coloration.  A few words on that: Creatures and plants benefit from not being eaten, duh.  That’s why, double duh, there are so many defensive mechanisms ranging from stinky skunks to rhinoceros horns.  Now let’s say you’re a well-armed bug, perhaps deadly poisonous or with a wicked sting.   That helps of course, and it helps even more to not be attacked to begin with: thus warning coloration.   Try to eat me, and YOU’LL REGRET IT!   Now let’s say you are harmless and likewise benefit from not being attacked.  If you look like something able to hurt an attacker, warning colors protect the harmless too.      We’ve all seen it:  things that sting and the mere posers use yellow and orange bands and blotches mixed with black to say “let me bee.” Okay, with that obvious foundation, here’s the cool part (as I see it).

Look at that bright orange basket of pollen on the leg.

Bumblebees have warning coloration mostly in the form of yellow and black bands.   There’s also orange, and that varies in an interesting way.  The showiest coloration on many bumblebees  is an add-on:  big showy baskets filled with colorful pollen on the legs of females.  

That orange pollen sac on the hip HAS to contribute to the warning coloration.

Could it be that a reward for being a busy bee is extra protection?  Not all bumblebees have the baskets of orange pollen.  Unloaded females don’t, and males don’t.  Perhaps some species never do.  In any case, some bumblebees have orange fur near where others have baskets of pollen.  Fake pollen baskets, that is. Examples include the “Tricolor Bumblebee” and the “Red-Belted BB.”  

Orange fur on this red-belted bumblebee looks much like the orange leg basket on others. Photo with public license USGS Bee Inventory.

In other words, as I see it, leg baskets full of orange pollen offer enough protection to be worth “mimicking.” Just to thicken the plot, even fly “wanna-bees” often have orange hips resembling the baskets.

Dronefly. I can’t sting, but look at my orange hips. Photo by Martin Cooper.

 
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Posted by on July 1, 2022 in Uncategorized

 

Nurse trees, seed rains, and arboreal facilitation

Nurse trees, seed rains, and arboreal facilitation

South Florida has expansive open space where sparse trees are isolated or in clusters, or over-abundant in dense single-species stands.    That makes it especially easy and fun to observe the relationships between “big” tree species and their smaller underlings, especially when it is clear that the smaller species benefit (or suffer) under their big green overlords.   

Now of course even a cow knows the benefits of shade.  Still, the obvious can be fun to observe in the way it “turns out,” and not everything about life under trees is as clear as shade vs. sun.   You might say the biological effects of a shady existence range from “duh” to subtle, speculative, and impossible to measure.

Tree roots alter the soil chemistry and associated microbes.  Deep tree roots lift water up to smaller shallow-rooted plants.  Roots from a tree or its leaf litter might generate natural herbicides, or improve the soil, or favor beneficial fungi.   Trees are giant funnels concentrating rain and the nutrients washed down the trunk in it.  Trees and their immediate neighbors may experience fires differently from the surroundings.    Trees may “discourage” their own offspring beneath their boughs in order to minimize “parent-baby” competition, or they may send up root suckers that outcompete other species.

Slash pine and dahoon holly at its feet.

In wet habitats trees often occupy or help create hummocks elevated above the surrounding marsh bottom.   A depression marsh or wet prairie is usually open, with isolated slash pines, pond cypresses, or pond-apples having shrubs and perennials crowded around the trunk bases.    Perched birds raining seeds and guano would account for some of this, especially in the cases of tree-base species characterized by bird-friendly fruits:  myrsine, dahoon holly, and wax myrtle.    But birds are not the whole story.  You’d think the berries would get around within the marsh, even by floating, yet you seldom find myrsine, dahoon holly, and wax myrtle on the deeper non-elevated marsh bottom.  The  deeper marsh bottom is owned by different species, mainly peelbark St. Johnswort,  buttonbush, and corkwood (Stillingia aquatica). 

Saw palmetto can form thick impenetrable almost-single-species “carpets” in some open wet (or dry) habitats.  The dense coverage can shade out almost all other vegetation.   A small number of woody species can sprout under the intense palmetto shade and eventually rise up above the smothering fronds.  Champions of this are two related hollies:  dahoon holly and gallberry (holly).    Seedlings of these two have the rare super-ability to tolerate the deep shade, and no doubt benefit from the palmetto suppressing their other competition. 

Hollies overtopping saw palmetto

By the way, staggerbush can achieve the same feat in dry scrub rising from under layers of palmetto fronds there.   Benefiting from protection in severe nasty scrub is understandable.  The endangered  four-petal paw-paw and likewise endangered apple-cactus reportedly need nurse trees in their scrubby  homes.  There is especially room for research on the roles of nurse trees in scrub, given the blazing sun, poor sand soils, deep water tables, and relentless coastal winds.

Gallberry holly in the shadows. No saw palmetto can hold me down!

Trees alter wind patterns.   The main scrub oaks locally are sand live oak and myrtle oak.   The two are almost always intimately intermixed around here, but in notably different proportions when tree-sized.   Maturing myrtle oak dominates scrubby zones surrounded by a windbreak of sand pines.  By contrast, larger sand live oaks dominate the open portions of dunes devoid of pine protection.

Myrtle oaks cuddly with sand pine

 
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Posted by on June 24, 2022 in Uncategorized

 

Thank you

To everyone who ordered our new wildflower guide 

(they are almost sold out)

All the existing orders will be mailed tomorrow (Wed. 6/21/22)

(if you want one and have not ordered it, email George before 8 pm today with your mailing address!  Can still go into tomorrow’s mailing, with invoice for $17)

rogersg515@gmail.com

John  Bradford, George Rogers

 
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Posted by on June 21, 2022 in Uncategorized

 

Which Came First, the Chicken or the Egg, the Moss or the Vine (Both?)

Which Came First, the Chicken or the Egg, the Moss or the Vine (Both?)

There’s something intriguing about the miniature self-contained ecosystems on swampy shady palm trunks. Lots of pushing and shoving, you know, lichen challenging moss kinda thing.   Who stands their ground, and who gets displaced?   But it’s not all pushin’ and shovin’.   Today’s nice friendly relationship is —so subtle you might question its reality, but I believe. 

Deep in the frog kingdom lives a moss called Syrrhopodon incompletus, which is hard to say but simple to spot as the dark green mats enjoying shaded palm trunks where the dark water is up over your ankles (unless you are on a nice boardwalk in Riverbend Park).   Brush off that spider, and look upward to the vines climbing the trunks.  Largely Virginia Creeper.

VA Creeper

With some luck in the right place you’ll see that the climbing vine and moss tend to hang out together, frequently with the moss flanking the vine as it rises into the tree.   

Moss and vine together

How that might come about is easy to imagine:  the moss makes a nice water-retentive substrate for the vine’s thirsty roots high above the moist nutritive ground.

Or:

Maybe the vine is a conduit for water and nutrients washing down the trunk.  You know, like those rain chains you can use in place of a downspout.    Maybe the vine is a “river” and the moss the “fertile floodplain” along the river.

Togetherness

Let’s go to the evidence.   Start with the vine using the moss.  It makes obvious sense.  Vine roots need water and nutrients, and moss is a storehouse. Secondly, studies on other plants in other places have shown epiphyte mats (such as moss) to feed plants with roots penetrating the mats (such as Virginia Creeper).   That is, our narrow case fits a broader known pattern. Third, and this is iffy at best, the Virginia Creeper’s clinging root pads grab the moss so tightly that when you pull the vine from the tree, it takes moss with it.  (A skeptic might say, that shows clinging but not proving extraction of benefits.)  As a final point of evidence, young growing vine tips too small to have been water conduits seem to follow the moss.     Personally, I think the vine uses the moss as a private rooting bed.

Tiny vine tips seem to follow moss.
Vine pulled free, holding on to moss (technically, liverwort).

What about the reverse:  the moss using the vine?  Again, it makes good sense.  How could water running down the vine not help the adjacent moss?  After all,  you can find examples of moss benefiting from water channels other than vine stems.   For instance, a fork in a tree can funnel a narrow stream of water down the trunk.  The moss likes those “streams.”   Similarly, there are places where a big epiphyte on the trunk, say Cardinal Airplant, catches water and then releases it as a drizzle, like a drippy sponge.   Today’s moss can flourish airplants.  Personally, I think the moss does use the vine as a private irrigation line.

Moss below tree fork.

So then, if this is all true in both directions (!), you have a remarkable situation of mutual facilitation.   I’m not suggesting that the two species have evolved to help each other—that would be “mutualism.”  But here we seem to have a win-win circumstance where two species seem to “luck into” each other, like a man with a pack of cigarettes, meeting a man with a book of matches.

Moss thriving below airplant drippage
Look how the vine “steers.”
 
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Posted by on June 17, 2022 in Uncategorized

 

Get our BRAND NEW wildflower guide!

Limited quantity (really) Strictly non-profit (we work at a loss) The summer flowers are out and beautiful!

Sample page 1
Sample page 2
Sample page 3
 
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Posted by on June 16, 2022 in Uncategorized

 

Clammyweed has Funny Flowers

(Clammy refers to the stickiness of the plants.)

Polanisia tenuifolia

Cleomaceae


Spider-flower, aka Cleome (Cleome hassleriana and relatives), is a garden flower like a friendly ghost haunting my memories of gardens long ago and far away.  That lovely cultivated species has a locally native mini-me, Clammyweed (Polanisia tenuifolia).  The thundering arrival of the rainy season has given Clammyweed a boost, making it a joy to encounter all spunky in scrub habitats.

Clammyweed on sterile white sand. The big upright candles are fruit pods. By John Bradford.

It has a floral oddity.   On any individual the flowers tend to be a mix of bisexual and male-only.   Put differently, all flowers have pollen-producing stamens (“male”), but only some have both stamens and “female” pistils (seed-making organs).    The several stamens are easy to recognize, being bright yellow.  The pistils look like bent fingers curving upward across the face of the flower to become the long skinny pods characteristic of Polanisia, and of Cleome.

Bisexual flower with “bee-fly,” the anthers pale yellow to left. The pistil shown by arrow.

The term for a mix of bisexual and male-only flowers on the same plant is andromonoecy (ANN-dro-MON-ee-cee), a word you’ll forget before the next paragraph.   But before you forget it, what good is andromonoecy?  Why would a species combine bisexual flowers with male-only flowers on the same individuals?   It’s rare.

Over the decades, various botanists have floated possible explanations.   The prevailing thought, laced with some speculation, is that because female flowers are “expensive,” a plant can sustain only a limited number of them, especially in a tough habitat like scrub.   That is, fruits and seeds resulting from a female flower make big demands a parent plant’s limited resources, like too many children in a human family.  In the thirsty nutrient-deprived scrub a stressed plant can afford only so-many plump viable seeds.   And it gets worse:  each fruit contains lots of seeds, with each seed requiring a successful pollen grain delivery.     You need a good bit of pollen even if fruiting is limited.

Male-only flower. No pistil. Large yellow nectar gland at center.

So then let’s see, redundantly.  Because the scrub-stressed plant can sustain only “so many” fruits filled with nutrient-demanding seeds, it is counterproductive to make too many bisexual flowers.    But still the plant needs plenty of pollen for even the constrained seed crop,  augmenting the pollen supply by making male-only flowers.   Moreover,  male-only flowers offer the added benefit of adding to the plant’s scent and visual display, and offer nectar and pollen food rewards.    “Hey bugs, get some nectar and pollen, and while you’re here drop off some pollen on that bisexual flower.”

That invites the question of,  is pollen from male-only flowers able or likely to fertilizer bisexual flowers on the same plant?   Neither answer is a “deal breaker,”  and data from similar situations suggests same-fertilization to be possible but unusual, an experiment waiting to be tried on Polanisia tenuifolia.

Both flower types visible. Note the pistil bent upward in the left-most flower. By JB.
 
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Posted by on June 10, 2022 in Uncategorized

 
 
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