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Fakahatchee Grass (Eastern Gama Grass)

Tripsacum dactyloides

(Tripsis is Greek for friction. Due to the nonslip foliage?  Dactyloides refers to fingers, no doubt the fruiting spike fingers complete with knuckles.)

Poaceae, the Grass Family

John and I devoted our investigative skills to Red Mangroves today, and before getting back into that swamp, a little more work must go down.  So in the meantime here’s something else observed this morning, if marginal to the priority of the day.

Tripsacum dactyloides is a big gorgeous nutritious grass with history.   Florida gardeners call it “Fakahatchee Grass,” plant it abundantly, and sometimes trim it to stubble.   Residents of eastern and central North America call it Eastern Gama Grass and value the species for pasture and hay. It hosts Skipper larvae.

Fakahatchee Grass Clumps

Tripsacum is the closest relative of corn without being corn or one of its known direct ancestors.  So a word or two on corn is something we all need.  With controversy over details, corn, Zea mays,  is the outcome of over 10,000 years of artificial selection starting with a cluster of closely related wild Zea grasses native to or near Mexico.  The complex of ancestral species is known collectively as Teosinte (tee-oh-SIN-tay).   Teosinte and Tripsacum dactyloides look strikingly similar, right down to the “ears.”   The ear of corn on ancestral Teosinte is a little finger of a few stacked kernels looking just like those on modern Tripsacum.

Here is photo evidence of the resemblance:

Fakahatchee achenes

Fakahatchee ears

Zea diploperennis

Teosinte primitive “corn” ear.  Corn 10,000 years ago. Photo by Matt Levin.

Tripsacum can cross with corn and with Teosinte.  This DNA-based evolutionary tree by biologist Elizabeth Skendzic and collaborators says it all, with today’s players all tied together:

tripsacum zea cladogranm by

Those Zea species are Teosinte.

Some researchers have suggested that Teosinte may have contributed genes to early corn evolution.  Either way,   the potential for its future contributions to corn are more exciting, maybe disease resistance, ecological tolerances, and untold other benefits.

If Tripsacum genes can get into corn, what about the reverse?  Concerned parties have pointed out the conceivability of GMO corn genes sneaking into wild Tripsacum.   Probably not something to lie awake dreading.

To sum it up so far, I like Fakahatchee Grass because every time I walk by one I think, “there’s an almost-ancestor to corn.”  The botanical equivalent of encountering a Neanderthal in WalMart.

How does Tripsacum differ from Zea?   Tripsacum has the male and female flowers on one spike, the females toward the bottom the males at the top.   In Zea the male and female flowers have separate spikes.  Ears of corn are the female spikes, and the corn tassels are the male spikes. In TripsacumZea hybrids either condition can take place.

Fakahatchee stigma

Fakahatchee pollen-grabbing stigmas

The “male” (pollen-producing) Tripsacum flowers dangle hundreds of jiggly anthers out into the wind where pollen shakes free for dispersal.

Witness the wiggle:  CLICK

The “female” (fruit-making) flowers poke their big reddish stigmas out like antennae to grab pollen off the wind.   They might not even need all that pollination apparatus.   The plants can form fertile clonal seeds without benefit of cross-fertilization.   That is, the seed can contain a clone of the mother plant.

If Tripsacum is an almost-corn, those kernels should have been on prehistoric menus.   They were. Tripsacum remains turn up in prehistoric caves.

There’s more to Tripsacum than corniness.   It tolerates terrible soils, yet grows big and robust.  How can jumbo happen on low nutrition?   Same way legumes, casuarinas, and wax myrtles thrive on terrible soils…nitrogen fixation.   Fakahatchee Grass reportedly has nitrogen-fixing (fertilizer-making) bacteria as root associates. That ability might be useful to share with corn.

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Dig deeper.

The literature on the history of corn would fill a silo, but readers might enjoy this

CLICK

 
9 Comments

Posted by on June 14, 2019 in Fakahatchee Grass, Uncategorized

 

Tracy’s Beaksedge Knocking Boots?

Rhynchospora tracyi

(Rhynch-o-spora means snout seed. Samuel Tracy was a U.S. botanist.)

Cyperaceae, the sedge family

There is no point to today’s profile, no novel discovery.  Just contemplating curiously a beautiful piece of creation.

Tracy’s Beaksedge graces much of the southeastern U.S. and southward usually where its feet are continually wet but not submerged perpetually, such as the squishy edges of marshes.  It mixes with other species or may dominate extensive stands, spreading by thin rhizomes.

Rhynchospora habitat

The sedge is a player in the Everglades, sometimes losing in competition to aggressive species encouraged by changing conditions.

The attractive feature of Tracy’s Beaksedge is its globose spikeball flower clusters resembling a medieval mace.   Funny thing, several other soggy-foot presumably wind-pollinated grasslike marshdwellers have similar spiked globes, such as bighead rush, Juncus megacephalus; American bur-reed, Sparganium americanum;  bur-sedge, Carex grayi; and Cuban bulrush, Cyperus blepharoleptos.  Go figure (another day).

Rhynchospora head cluster young with styles

Young flower heads, the elongating stigmas jutting forth, no anthers visible yet.

The floral biology of Tracy’s beaksedge is odd and delicate. Each bump in the mace is a tiny branch, a spikelet.   Each spikelet, within my experience, has two flowers, the larger flower having both female and male organs.   The smaller flower is strictly male.  Both flowers resemble microscopic ears of corn, the same shape and swaddled in green leaf wrappers. That the spikelets have an “extra” all-male flower suggests a bonus boost of pollen augmenting that from the hermaphroditic flower.

Below is a dissection of one spikelet. All the following photos are the same spikelet.

immature spikelet

Spikelet unopened, with style to right. Scale is mm.

immature spikelet opened labeled

Spikelet opened, and the bisexual flower opened. Style to the right. Perianth bristles are non-sexual flower parts. Anthers are greenish-yellow.  Second, male, flower is near-vertical on the left, still unopened.

second flower opened closeup

The second, male, flower removed and opened. The yellow-green structures pointing left are anthers.

It might be helpful to note that the main female organs are the seed-containing ovary topped with a beaklike style responsible for capturing pollen as part of the sexual cycle.   The male organs are stamens, each topped with an anther full of pollen.

In young flower heads the female pollen-catching styles poke out making the entire head a spiked ball, while the anthers remain in their wraps. The flower-head thus starts out entirely or predominantly female.  The styles elongate dramatically.

Rhynchospora long styles black backgtound good

Stigmas elongated. No or almost no anthers visible yet.

As the head matures, the styles elongate, twisting and curling to extreme lengths, sometimes doubling or more the length of the spikelet.   They transform from little spikes into coils and curls.

Rhynchospora long style

Spikelet with long mature or post-mature twisty style.

As this progresses, the anthers belatedly emerge, mostly in the “middle-aged” heads.   Such heads have both styles and anthers exposed simultaneously, so the two sexes seem to overlap, although the styles are mostly withering.

Rhynchospora older head with anthers 2 good

Middle-aged head, the styles mature and post-mature.  Anthers now visible as two pale pairs at 3 and 4 ‘clock..

The long twisty styles eventually die back to stubby points, making the old spikey head look again much like the young ones.  The style bases then remain as a beak on the seedlike fruit.

Rhynchospora head with old styles protruding

Older head with style bases protruding.  These style bases are the beaks on the seedlike fruits.

Rhynchospora achene

Fruit on the right, with perianth bristles.  The beak protruding to the left is the style base. Scale is mm.

How many flowers come into physical contact…you might say, “mate” during pollination?   There are probably cases where wind-pollinated species in crowded stands blow into each other.   I think Tracy’s Beaksedge is the world’s prime candidate for “head to head” wind-powered pollination.

The macelike heads with their styles and anthers hanging out knock wind-blown into each other all day long.  I’ll bet pollen gets traded during the collisions and/or shaken loose and then exchanged over very short distances.

Normal “wind pollination” is wasteful, given that any given pollen grain has an infinitely low likelihood of docking on the stigma of another plant.  It resembles hunting ducks by shooting blindfolded into the sky.   Think of all the wasted ammo/dead duck!  If I want to bag a quacker, my odds are better if I walk up and bean a Muscovy with a 2 X 4. (I would never do that.)  Those mace-head collisions seemingly would increase the odds of pollen transfer.

The heads can have pollen stuck all over them, so if such a pollen-dusty head smacks the stigma on another head, the odds of pollination aren’t bad.    The head may even collect pollen from other individuals off the wind or by collision, and then pass it along in subsequent collisions.

Note that I am not suggesting that conking heads is the only means of pollination.  I don’t even KNOW if it matters.  Pure speculation.  How would you even test such an hypothesis? (Radioactive pollen?)

Being rhizomatous, head-bonking neighbors might be clones of each other, in a genetic sense amounting to self-pollination,  although not necessarily so.

Watch Tracy’s Beaksedge bop in the wind:

KNOCK here

Sometimes after the bonk two stems stay united:

Rhynchospora two linked

Heads from two neighboring stems locked in embrace.  Looks like a good opportunity for pollen exchange! These married couples are frequent in the marsh.

 

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What Do Tollund Man and Cypress Creek Natural Area Have in Common?

(They both contain Pale Smartweed)

Persicaria lapathifolia

(Persicaria reflects resemblance of the foliage to peachy leaves.   Lapathifolia suggests the leaves resemble sorrel.)

Just like quiet tudents in a classroom, sometimes modest weeds have secret stories.   True today of one you’d miss unless you really care…pale smartweed, one of the many species of smartweeds, Persicaria, in South Florida.     The species turns up in archaeological deposits near the Bering Strait, so maybe it came to the Americas ages ago by the same Alaskan route as the first humans.   Or maybe not. Who knows.   Certainly not authors who state pseudoauthoritatively, “introduced from Europe.”  In any case, the plant inhabits most of North America, Europe, and far beyond.

Persicaria lapathifolia nodding 1

Another name for pale smartweed is nodding smartweed.

What’s more interesting than its span in space is its span in time.  The time machine takes us to two persons of interest:

  1. Tollund Man was guest of honor at an Iron Age necktie party and got tossed wearing his noose into a Danish peat bog some 2400 years ago. Mr. Tollund was peat-pickled so well he looks freshly embalmed, so finely preserved you can determine his last meal. It included seeds (achenes) of today’s species.
  2. Grauballe Man wound up similarly, although with a slit throat. His tummy likewise contained pale smartweed seeds.

Pale smartweed has a presence in Danish Iron Age archaeology.  One homesite contained a liter of the seeds.   Was it an ancient crop?  Probably.  Not my original idea, the smartweed perhaps snuck into significance mixed with wheats, millets, or other grains.  Observers note heterogeneous seed sizes, allowing the smartweed to winnow well among other grains.  And it is a great producer…a single plant reportedly can make almost 20,000 seeds. That’s a lot of paleo porridge.  You know, I’m going to have to try some when it gets ripe here in Jupiter.

persicaria lapathifolia nodding 2 May Cypress Creek

The species could have come to culinary attention via its medicinal history.  Pale smartweed has a long association with humanity in traditional medicines.  It is loaded with bioactive chemicals. (Please do not eat the weeds, even if I am going to try some smartweed seed gruel.) ((Famous last words.))

Persicaria lapathifolia ocrea 1

The species has a distinctive leaf base. (That wraparound sheath is called an ocrea.)

Listing old uses for prehistoric medicinal plants gets tiresome.  Name a human ailment, and you have found a use for the plant.   I like unusual and specific applications.   Abusing pale smartweed releases a soapy slime. The sap contains sudsy compounds, often toxic, called saponins.   Saponins sometimes are fish poisons, and yes, pale smartweed has helped harvest our finny friends.  It has also lathered up the laundry.  You could go down to the creek, wash your drawers, and enjoy the catch of the day. And if poison ivy made you itch, no problem, the soothing lather was a poison ivy salve before an ocean of calaedmine lotion.

 
1 Comment

Posted by on May 24, 2019 in Pale Smartweed, Uncategorized

 

Colombian Waxweed is a Seed Trebouchet (maybe)

Colombian Waxweed is a Seed Trebouchet (maybe)

This article has a lot analogies.

Cuphea carthagenensis

(Cuphea comes from Greek for curved, noting the bent flower base. Cartagena, Colombia, is the site of the original specimen.)

Lythraceae, the Crape Myrtle Family

A running theme in my botanical life is, hey, no need for exotic locales to see the best of botany, the back yard ain’t bad.   The plants we tromp while looking for something fancy are often overlooked treats, like shy classmates.  Nobody told Mother Nature to put all the good evolution in tourist brochure locales.   As an example, in wet disturbed areas across much of the Southeastern U.S. and far southward is a pretty little plant you might call a wildflower, or a weed, or “Colombian Waxweed.” Books will state it is not native to Florida, but I never trust such designations with widespread self-fertile masters of dispersal having unknown histories.  When and how it got to Florida from tropical American latitudes is anybody’s guess.

Cuphea carthagenensis 4

Colombian Waxweed by John Bradford.

Gardeners know the genus Cuphea from such beauties as bat-faced cuphea, candy-corn, cigarplant, and Mexican-heather.   They are pretty, including Cuphea carthagenensis in a modest sort of way.

The long sticky hairs on Cupheas are so graspy-claspy they could remind an observer of the tentacles on carnivorous sundew.  Here is an excerpt from Popular Science Monthly 1904:

cuphea pop sci monthly

Look closely at the photo below of a partial flower touched by a steel needle.  The hairs grabbed and hugged the shaft, conforming instantly to its shape.   Those are some serious “tentacles,” marauding ants beware!

cuphea clinging

Cuphea flower tube with clasping hairs hugging needle shaft. They grabbed the needle instantly upon touching it.

A second point of human-Cuphea contact is the oil from its seeds garnering attention relative to human dietary health, possibly as oil crops.   The main function of seed oils is as compact high-energy nutrition for the embryo.   In a wetland weed, the oils might additionally resist water damage.

Cuphea carthagenensis has one of the weirdest seed dispersal systems I’ve ever seen.  The “placenta” is the structure inside a fruit where the seeds are attached.    Repeat, inside the fruit.

In today’s species the world’s wackiest placenta thickens, lengthens, and bends upwards ripping open the horizontal flower, busting through the top off the fruit and opening the overlying flower tube.     Think of Dracula sitting up in his coffin, tearing through his shroud (the fruit) and popping the top off the coffin (the horizontal flower tube).

cuphea opening

Cuphea seed presentationcropped

The open flower tube is pointing toward us at the bottom of the photo.   The big pinkish placenta has risen, opening the top of the flower tube.  Six seeds are visible on the placenta.

This leaves a very odd “fruit” looking like a bent shovel, the shovel handle (Dracula) being the placenta, and the toothed shovel blade being the remains of the torn flower tube. Upon rising, the enlarged placenta has seeds on it, dispersing to leave the placenta bare.  The shovel blade is held. nearly horizontal.  The placenta leans back. The unit is hinged to the main stem by a short stalk attached near the angle where the blade meets the handle

cupheaseedless

Open flower tube (shovel blade) to the left.  Placenta (shovel handle) pink on the right.   Seeds removed.  The hinge is behind the blade-handle junction.

The exposed placenta passes through a pinkish phase.  Why?  Could the color attract creatures involved in dispersing the seeds?   Birds?  Possible, but the shovel units are tiny, and birds just don’t ring likely.  Insects?   Possible, but there is no apparent reward, I’ve never seen any,  the  seeds are not particularly sticky, and the big seeds would be a massive burden on a bee, although an insect visitor coud shake them loose if not cart them off   Again, doesn’t strike me as likely.   Rather, I suspect the colorful placentas enhance the overall attractive display of the entire plant, helping to draw distant pollinators, who once nearby divert to the actual flowers.    Room here for speculation and research!

More abundant than bees, more reliable, and vastly more powerful is the driving rain.   A  raindrop has punch, and the open flower tube shovel blade is sized and positioned for raindrop bombing.

cuphea splash

A raindrop smacks the blade downward, popping the hinged placenta up to catapault the seeds.  It makes sense for a plant inhabiting rain-puddle habitats to launch seeds during the deluge.  The seeds go when and where the rainwater goes.

Why is the blade toothed?  Maybe to help capture raindrop impact, yet to also allow drainage.

Cuphea Trebuchet_Castelnaud

 
2 Comments

Posted by on May 17, 2019 in Cuphea, Uncategorized

 

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 Are Lichens Tree Parasites?

Never say never.

The dogmatic answer to that frequently posed question is a comforting “no” echoed throughout garden publications.  Here is a typical statement from the New Mexico State University Horticultural Guide H-167:

“Lichens may rest directly on the bark or be attached shallowly to it, but they do not enter the inner bark where food is transported, and hence do not rob the tree of nourishment. They are not parasites.”

IMG_7376

Lichen with the emerging side-branch kaput.

A trouble with dogmas is that while they spread and simplify,  gaining emphasis, occasionally somebody goes back and checks them out.   Not that finding parasitism in lichens is new. One of the links below dates from the 80s.    And, because lichens are not a single “thing,” but rather many unrelated species in diverse symbiotic relationships,  ixnay on big sweeping generalizations.

I’m not posting this to shock treehuggers.   Seems that under most circumstances most lichens are mostly okay. There’s no existential threat, arboreal apocalypse, or actionable garden info here.    Just interest…

Assuming that lichens are never parasitic is actually too good to be true.    To cite recent experience, would you leave the dog alone with an Italian sub?  A fox with the henhouse?  Me unsupervised in a Dunkin Donuts?   Lichens are fungi bundled with algae or cyanobacteria.   Fungi are tissue-invading machines.  That is what they are good at.   Their threadlike hyphae penetrate and digest organic matter.  So why should a lichen fungus always “behave” and never help itself to a bit of the host tree’s substance?  A little side-steppin’ shoud be expected.

What’s remarkable is that lichen fungi are not more parasitic to their hosts, although the hosts have defensive mechanisms, most conspicuously shedding bark and pesky pests thereon.   Lichen fungi do invade tree tissues, probably mostly on young twigs.   Researchers have long been aware that the lichen “oak moss” Evernia prunastri  and species of similar Ramalina penetrate the bark, including the living sugar-conducting layers, and sometimes into the wood beneath. “Lichens are not parasites,” my ass.

Pause a moment.  It may help to clarify that bark (phloem) is dead to the outside but alive and transporting sugar in its inner layers.   Immediately interior to that is the water-conducting wood (xylem). Together the phloem and xylem are the circulatory system of the branch.

Botanists who have looked into lichen parasitism have found that host branches can lose their leaves outward to the leaf tip from the point where the lichen is attached.  That is, water transported out the branch after passing the lichen seems to cause leafdrop. This could be due to toxicity and/or to tissue damage.   Alternatively,   and not an idea original with me, it could be adaptive for the lichen to defoliate the branch for increased light exposure.  Weirder things are known.

It is not just oaks.   Locally on Bald or Pond Cypress small tufted lichens* sometimes perch on young branchlets, which may become leafless or lifeless out past the lichens.  In the photo below the Cypress branch is healthy below  (to the right of) the largest lichen, sprouting side branches.   The side branches at the point of lichen attachment, however, are dead, and those farther toward the branch tip (left of the lichen) are stunted or missing.

Ramalina damage on Taxodium 1

All good until you get to the large lichen.  At the lichen attachment and beyond (to the left) , side branches dwindle.    For that matter, the smaller lichens seem to have killed and shortened side branches at their attachment points too.

To see if the lichen affects the living inner bark and/or into the wood, I sliced branches lengthwise at the point of lichen attachment.  Bark at the lichen attachment point is thickened and different from bark elsewhere.

Taxodium with Ramalina

At the center, bark (brown layer) thickened under lichen (gray) attachment.  Normal bark appears at far right.

Looking more deeply, the wood interior to the thickened bark is discolored as in the photo below:

Ramalina wood damge

Discolored wood under lichen attachment point.   Bark is brown layer on the right.

To sum it up, these lichens are entering the living inner bark and penetrating (or at least damaging) the underlying wood, killing or stunting side-branches, and ultimately killing the host branch tip distal to the lichen.   But fret not, the suffering twigs are few,  and maturity brings toughness ….so the outcome seems merely a tiny bit of free pruning.

Ramalina wood discoloration 2

Wood discoloration under lichen attachment.

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Dig in deeper:

Click for an older paper on this topic.

Click for some recent views from the West Coast, and sources.

The identity of the photographed lichen is not relevant to today’s article.  I’m no lichen expert and  have no interest in peripheral concern with species name.   I’d be glad to share my tentative identification privately by e-mail upon appropriate inquiry.

 

Ground Hog Day In the Periphyton

John and I worked today in the Haney Creek Trail natural area near Jensen Beach, Florida, although the scope of the discussion extends to multiple local wild places.  An intriguing habitat type has no particular name:   Let’s call them freshwater mudflats.

mud flat

Pond with aquatic species (green), in a ring of seasonal freshwater mudflats.  During the wet months the entire area is inundated.

In these places seasonal inundation alternates with the pond bottom mud exposed bare naked anew each dry season.  Sort of like Bill Murray’s Groundhog Day…ecological succession set back to “go” in an endless loop.

I don’t know to what extent various mudflats around here are the result of human activity.  Either way, they are an exotic universe to explore

On the flat I’m using to base today’s account approximately six species dominate, accompanied by several subordinate interlopers. Different mudflats or even different portions of the same flat have different species mixes.   The list below excludes the truly aquatic species persisting where the water has not receded.   We’re talking about “land plants” on drying mud.

Here’s the dominant species list…

  1. Dog Fennel (Eupatorium capillifolium) in the Aster Family. This smelly weed invades just about any disturbed site where the sun shines, from cow pastures to today’s habitat, where it seizes upon the extreme disturbance of wet bare mud. Ideal!   The seedlings are probably the most abundant babies on the site.
IMG_7004

Dog fennel seedling in the periphyton mat.

2. Sweetscent (Pluchea odorata), likewise smelly, is in the Aster Family. Its pollinators are diverse, yet  in my experience mostly abundant enthusiastic wasps.  The tiny individual flowers are clustered, with each cluster swaddled in small purple leaves (phyllaries) giving each  cluster the look of a single urn-shaped flower, resembling flowers in the Blueberry Family.  Wasps poke their faces into the opening of the urn.

Pluchea with wasp 2

Here is a brief clip of a wasp “working” the urn-shaped flower clusters…

CLICK (action slowed a little)

  1. Mock Bishopweed, aka Herbwilliam (Ptilimnium capillaceum) in the Carrot Family has its delicate white flowers in umbels reminiscent to northeners of Queen Anne’s Lace.

IMG_7089

ptilimium flowers close1

Mock bishopweed flowers – they can self-pollinate

4. Lax Hornpod (Mitreola petiolata) in the Logania Family was the topic of last week’s blog.

5. Bighead Rush (Juncus megacephalus) in the Rush Family loves mud. Its spherical seedheads host a moth larva whose identity I’m not sure.

juncus megacephalus with moth larval cases

Bighead rush. The white items at 4 and 6 o’clock are moth pupal cases.

6. Fragrant beaksedge (Rhynchospora odorata) in the Sedge Family is scattered throughout.

A mix of unrelated plants, and surprisingly small species count.  The surrounding woody-swampy areas house probably 100 different species, so how does a seasonal mudflat filter the community to a dominant half-dozen plus  a handful of others?

Let’s look at the environmental difficulties.

Difficulty 1.  SEASONAL WATER EXTREMES.  The plants have to cope with flooding half the year, then saturated soggy soil, then sun-baked drying mixed with intermittent deluges.  How many species can transition from flood to desert?   Few of today’s species actually live in standing water.   Rather, they recolonize the mud each year by arriving anew via wind-borne seeds and/or persisting in the mud seedbank.

Dog Fennel and Sweetscent seeds (achenes) fly on parachutes.   Although they may also survive in the soil seedbank, their seedlings seem scattered relatively randomly on the mud as opposed to showing a strong relationship to the receding waters. I vote for “new rearrival annual” as  important for the parachute species.

All the others, by contrast, have small, hard, durable seeds or achenes easily dispersed by water but not by air, and  presumably surviving in the pond bottom mud from year to year.   Published research documents this ability for Mock Bishopweed’s seedlike fruits, which float.

ptilimnium fruit close

Mock bishopweed fruit floats, and can remain viable for at least several months.

This species seems to prefer germination in the natural “mulch” formed by dead aquatic species…out with the old, in with the new.   Its tiny seedlings flower as toddlers, making sure of reproduction before the next flood.  The flowers can self-pollinate, further assuring seed production before Noah time.

ptilimnium baby with dragonfly

Baby mock bishopweed, already with flowers.  Mulched among dead aquatic sedges killed by dropping water level.

Lax Hornpod has the most conspicuous relationship to receding waters.  On the wet mud within a foot or two of the water line its seedlings rise in abundance.    With increasing distance from the falling water the older Hornpods diminish in abundance and increase in size.   The pattern suggests that the seeds wait in the mud ready to sprout the moment the water recedes.   It too is self-pollinated.

mitreola babies

Hornpod babies pop up like mushrooms the moment the mud surfaces.   These are a foot back from the water’s edge.

Difficulty 2. BAKING IN THE SUN  Brutal sun exposure goes with the territory.   Except for Sweetscent and Hornpod, all six species have narrow leaves or finely divided leaf segments adapted to minimizing sun exposure while maximizing wind-cooling.    The filamentous leaves of Mock Bishopweed and Dog Fennel are almost identical:

IMG_7233.JPG

Dog fennel on left. Mock bishopweed on right.

Sweetscent has  protective hairs and secretions.    Hornpod has the most-“normal” leaf blades and may be the first to succumb to drying and heat.

Difficulty 3.  HORRIBLE SOIL The plants live on sand mixed with fossil seashells.  Submersion half the year interferes with “normal” soil microbes, with nutrient cycling, and with symbiotic mycorrhizae.   Nutrients wash away during inundation.  Wet soils generally have only a thin organic layer.    Oxygen would be scarce much of the year.   At some points the sandy soil is suffocating wet, and at other times bone dry.

Flooding, suffocation,  radiation…No wonder only elite species cope!

The mud-dwellers have one apparent advantage…periphyton. Periphyton is the mat of algae, cyanobacteria, fungi, rotting detritus, sticky goo, and associated microfauna that floats in the shallow waters during the wet season and settles as a crust on the mud as the waters recede.

IMG_6999

Stranded dry periphyton mat.

How does the mat impact the dry-season plants living on it?   This is poorly studied, although a 2018 investigation by biologist Lu Haiying and collaborators considered this with respect to paddies.  Among their observations, the periphyton crust:

  • Is involved in nutrient cycling between the water and soil, retaining and releasing nutrients, sort of a green liver
  • Improves the soil structure
  • Serves as a slow-release bio-fertilizer

The periphyton may help overcome dormancy in seeds of some species.   Just a guess, but an experiment to try, especially with Lax Hornpod.  Periphyton probably blocks soil drying, and retains rainwater.  Further, it dampens out temperature fluctuations.

All the nutrients captured, modified, or created by the algae and cyanobacteria during the wet months eventually become available slow release to the mud-dwellers.

Periphyton is loaded with Cyanobacteria, and many of these are nitrogen-fixers.  The brief clip below shows the Cyanobacterium Oscillatoria wiggling in the stranded periphyton crust after rewetting (action speeded up a bit).

CLICK to see the dry periphyton resurrect.

peri wakes up

This graph shows carbon dioxide production (respiration) by a few chunks of “dead” dry periphyton crust.  They were waterd at the start of the graph.  The chunks sat flatlining for about 180 seconds, then life!  The periphyton wakes up and “starts breathing” within 3 minutes of moistening.

 
4 Comments

Posted by on May 3, 2019 in Periphyton, Uncategorized

 

Lax Hornpod Needs Neither Bird nor Bee!

Mitreola petiolata

(Mitreola means little mitre, because the fruit looks like a Bishop’s mitre.  Petiolata indicates the leaves have stalks.)

Loganiaceae

Mitreola petiolata is a worldwide warm-climate weedy species whose point of origin and history of dispersal is unknown.  Its intercontinental range include all of Florida.  Let’s call it a native species.

mitreola petiolata plant - Copy - Copy - Copy

That huge pantropical distribution stands out in the small genus Mitreola where most of the other species have narrow ranges scattered in Africa. Asia, Australia, Borneo,  and Madagascar.   Mitreola sessilifolia, similar to today’s species ranges across Florida and much of the southern U.S., extending into Mexico.

mitreola map

Each yellow circle represents one Mitreola species.  Mitreola petiolata is “everywhere,” the purple lines showing its global reach.

Mitreola petiolata has pretty little white flowers with a curious donut of hairs partly blocking the flower’s throat.

Mitreola fresh flower

Highly magnified. The flower is about 1.5 mm in diameter.

And speaking of curiosities, the pod is a two-horned “Bishop’s mitre.”

mitre

mitreola fruit - Copy

Pod

Weedy species such as this distributed far and wide often reproduce free of the need for a male plant and a separate female mate to establish together for cross pollination at each step during world conquest.  Botanical imperialism is more efficient if you spawn alone.  There are different ways to accomplish that.   Mitreola petiolata uses extreme self-pollination within individual flowers.

mitreola inflorescence

Back in 1841 botanists John Torrey and Asa Gray noted, “the pollen tubes are often so copious, even in dried specimens,  as to fasten the anthers to the stigma.”  This observation is 178 years old, and I’ve never seen anyone record checking it out since.   It is about time! This is going to be better than Geraldo Rivera opening Al Capone’s vault!  Get ready!

Be patient one moment though, after almost two centuries the mystery will hold 30 more seconds while a little background refresher may help explain what those two were talking about.   In a “normal” textbook species, a bird or bee transfers some dustlike pollen grains from the pollen-producing anther of one flower to the pollen-receptive stigma of another flower.   Then a tiny thread called the pollen tube grows like a root from the newly landed pollen grain down through the stigma and style to the ovary, carrying sperm to fertilize the baby seeds there.  To repeat, the pollen tube is a tiny sperm-bearing filament extending from the pollen grain to the baby seed within the newly pollinated flower.   Here is a helpful diagram:

pollen tube diagram2

Textbook normal pollination. Pollen grain (yellow) deposited onto stigma (blue) by pollinator.  Then pollen tube (yellow) snakes down to deliver sperm to seed (violet).

Okay then, we now can carry forward knowingly. Mitreola petiolata has a ring of five pollen-making anthers attached inside the flower. The anthers unite to form a cap covering the  stigma   The pollen grains inside those anthers do something weird, they all sprout pollen tubes while still inside the anthers that made them.  Today’s species skips the messy business of birds, bees, and pollen transfer to a different flower.

mitreola flower diagram - Copy - Copy - Copy

Top image:  diagram of the Mitreola petiolata flower.  Middle image: anthers (yellow) united into cap over stigma.   Bottom:  anther cap has been pulled away from stigma revealing  pollen grains and their pollen tubes penetrating into the stigma.

The countless premature pollen tubes form a network lacing the anthers to each other and to the stigma in a wild orgy of self-pollination.   When this has occurred, as Torrey and Gray noticed back the year President William Henry Harrison died in office, the mob of pollen tubes have stitched the anther cap firmly to the stigma.

MitreolapetiolataApril25AnthersStuckToStigma - Copy

This is the base of the flower with the petals removed.  The anther cap (gray above the center)  is tied to the stigma hidden beneath it.  The 3 white flaps are anther attachment points left behind when the petals were torn away…remnants of the petals and their connections to the anthers. This photo shows the same info as the middle image in the diagram above.

When the anther cap is yanked away from the stigma under a microscope, the stigma remains covered with pollen tubes burrowing in for sperm-delivery.

MitreolapetiolataApril24style - Copy

This is the stigma with the anther cap pulled off.  The tangle on the left is a mass of pollen grains and pollen tubes left behind from the anthers, and penetrating the stigma.  Extreme self-pollination! The style is the shaft in the middle, and the large body on the right is the ovary.  This photo matches the bottom image in the diagram above.

I’ll bet every flower on every Lax Hornpod in every wet meadow around the Globe matures a fruit filled with self-fertilized seeds.  It’s an inside job!

 
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Posted by on April 26, 2019 in Mitreola petiolata, Uncategorized

 

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