RSS

Giant Whitetop, Broadleaf Painted-Sedge

Rhynchospora latifolia

(The name means wide-leaved beak-seed.)

Cyperaceae, the Sedge Family

Today’s wildflower is the chosen topic because it is so pretty and so eye-catching now in mid summer.   Rhynchspora latifolia decorates wet meadows and similar habitats standing 3 feet tall, waving its white and green flower heads above its neighbors.    Its smaller cousin Rhynchospora colorata has fewer white lobes, has the lobes not narrow abruptly at the green parts,  often grows more crowded, and prefers slightly less wet sites. According to reports R. colorata prefers alkaline as opposed to R. latifolia in acid locales, although I suspect that habitat difference is a bit overstated.  I’ve seen the two growing within a few yards of each other. Checking that out with a pH meter would make a great class research project.

rhyn lat flower head

The white “petals” are leaves (bracts).

What’s famously odd about the two rhynchosporas, additional Rhynchospora species not represented locally, and a smattering of other sedges and grasses is that they are fully or partially insect-pollinated species in huge plant families the textbooks generalize as wind-pollinated.  These are plants whose ancestors turned away from insect-pollination to wind, then the painted-sedges reverted to insects..

That’s like going back to golf after you throw away the clubs.  They had to re-evolve all the insect-related pollination apparatus starting from scratch.   Colorful petals were long-gone so the replacements are false petals made of white leaves (bracts) green at the tips.   Nectar is gone too, but there’s bright yellow pollen to attract and feed visitors.   What’s dismaying is that these flowers have re-evolved sweet floral perfume, released it seems only briefly in the morning. Most of the day they are without fragrance, but at perfume time they are surprisingly potent.

Morning seems to be the main time for action.  That is when all or most of the pollen-bearing anthers come forth, although they can persist all day.   That is also when most of the pollen-receptive stigmas come forth, although some may be apparent all day.

Rhyn lat stigmas showing 2

Spikelets (each thick white unit is a flower cluster).  Anthers are yellow. Stigmas are smaller, finer, and white.   Each spikelet is wrapped in bracts and contains several crowded flowers.

In each tiny flower the pollen-making anthers emerge from the bracts enclosing them and start releasing pollen before the pollen-receiving stigmas mature and emerge.  The anthers are bright yellow and prominent.  The stigmas are white, small, and held close to the flower head. Male-first is called protandry (PRO-tand-ry).  However, the flower head is made of hundreds of flowers, so that even if one flower is “male,” adjacent flowers may be in the female phase, or transitional.    Thus the entire head can be a mass of male and female flowers, although late in the day the balance shifts strongly to persistent stamens as most of the stigmas wither.

Rhynchospora latifolia anther tips and good stigmas 731AM 2

Spikelet in early morning. Anthers just peeking forth. Stigmas (white)  are from different flowers in same spikelet.

The species needs a preponderance of anthers as opposed to stigmas, because the roles the anthers have in attracting and feeding pollinators, and in manufacturing massive quantities of pollen.

If functionally male and female flowers can be mixed close together in the same spikelet, does self-pollination occur?   Evidence that effective self-pollination is unusual or nonexistent is that  many flower heads mature no fruits, or very few, while some others are productive.  Fruit productivity reflects luck in cross pollination.  No visitors from other flower heads carrying pollen from afar, no fruits.

If thwarting self-pollination does not seem a  key reason for  protandry in individual flowers, what is the benefit of a flowering making stamens first?   I don’t know, but have a speculative notion:

As the stamens and stigmas mature they have to pass through a narrow bottleneck of tiny leafy bracts in order to see the light of day.  If the soft and delicate stigmas matured first they might be crushed in the bottleneck by the large, firm, pollen-filled anther bullies.   Like letting the mice off of Noah’s Ark before the horses.    Once the anthers have “cleared the door,” it is safe for the more delicate stigmas.

rhyn lat spikelet diagram

Reported visitors include bees and hoverflies (syrphids), an interesting combo given that both feed on or gather pollen.

 

Tags: , , ,

Torpedo Grass, You Can’t Kill It With Vinegar

Panicum repens

Poaceae, The Grass Family

The names:

Panicum refers to the panicle, a branched, flower cluster.

Repens means creeping.

Torpedo grass is the perfect name.  Not only does the sunken rhizome look like a torpedo, it behaves like one too.

 

The essentially tropical species torpedo grass is of unknown origin, generally but not unanimously regarded as indigenous to the Old World, and invading the Americas at least as far back as the 19th Century. The grass once served as a forage grass, although it has some livestock toxicity.   I wonder if it is experiencing a northward range extension via global warming. Nowadays torpedo grass is one of the premier weed pests in southern states, and around the tropical world.

panicum repens inflor

The grass is OUTRAGEOUS!   Here are some TG OMGs:

Rhizome pieces can grow to the surface after burial of over 12 inches.

They survive at least 60 days buried.

Living rhizomes have reportedly turned up under soil about 20 feet deep (huh!?) and under 5 feet of water.

Rhizome segments remain viable after at least 10 weeks of floating.

They can dry out and then later sprout.

The torpedo can penetrate wood and asphalt.

Growth can exceed half an inch per day.

A single rhizome node can make 20,000 buds in a year.

Torpedo Grass covers over 16,000 acres around Lake Okeechobee.

Usually associated with wet habitats, the grass can occupy dry sites, even in scrub.

Salty habitats are just fine.

The species is allelopathic, that is, it poisons competitors.

What a grass!,  despite herbicide, fire, and plowing attacks, it blankets countless acres. In some places, especially those under shallow water, much of the year, TG can form acres of “lawn,” yet I can’t maintain a healthy St. Augustine front yard to keep the HOA golf cart spies content.  Proud homeowners keep their lawns lush with fertilizer.   So how can today’s species make a big happy carpet without  added fertilizer?   Well, maybe it has some, not counting whatever nutritional pollutants are in its wet habitat.  Let’s look into TG and nitrogen:

Over the last few days I’ve botanized a multiacre torpedo grass invasion on a severely disturbed wet meadow.   The surface is essentially bare wet sand.  How sand can “fertilize” tons of torpedo grass might seem a mystery, but here’s the thing:  Mixed grass-legume pastures feed livestock sustainably because the legumes “fix” nitrogen by transforming atmospheric nitrogen gas to ammonium, which plants can use directly.  Fixed nitrogen is the fertilizer nutrient needed in by far the highest volumes.  A legume-heavy field is largely self-fertilizing.   The field west of Jupiter is not a monoculture of torpedo grass, but instead is a mix of the grass and a substantial component of legumes:  Indian shyleaf by the ton,  thousands of wild bushbeans, and additional legumes scattered in small quantities, such as sensitive-pea, alyce-clover, cowpea, and danglepod.  Grass plus legumes, almost nothing else.

Panicum repens Aschynomene meadow

Torpedo grass stretchin’ out so far and wide.   But wait a moment—all those taller plants are Indian Shyleaf, a nitrogen-fixing legume

That t-grass responds to added nitrogen is demonstrated in published experiments.  You can deduce the same from one clump in my study area…taller than the rest of the torpedo grass, and darker green.  Why?  The happy grass sits atop a big scary ant nest, and no doubt the anty debris and waste is a nitrogen boost.

panicum repens on ant mound

Clump of torpedo grass taller and greener than its neighbors.  Go look…well, it is on an ant mound.  The non-grass plants visible are legumes bushbean and shyleaf.

panicum repens ant nest

If you don’t believe me about the ants, stick your hand in there for ten seconds.

It isn’t all about legumes and ants.  The ability of grasses to thrive in vast quantities without human-added fertilizer is becoming increasingly attributable to symbiotic nitrogen-fixing bacteria, not in nodules, as in legumes.   Instead, nitrogen-fixing bacteria live in the grass’s root zone, or sometimes housed within leaf bases around rhizomes,  or even within the grass tissues.  This area needs a lot of study.   Nitrogen-fixing bacteria have been reported a couple times associated with torpedo grass.

More astounding are additional bacteria associated with the grass and able to neutralize nasty acid soils, extending the already super powers of the torpedo grass into acid environments.

Weirdly, TG seems to be taking over the world despite poor seed production, at least in places.   The species is reportedly unable to make viable seed in large parts of is range, including much of Florida.   A study at Lake Okeechobee where the grass is out of control failed to find viable seeds in the soil seedbank.  Thus most of the Florida reproduction is clonal,  such as by floating rhizome fragments, also by axillary buds produced along the rhizomes.  Just think, in a genetic sense a clone is one individual.  That would mean South Florida is being devoured by an immense immortal botanical amoeba.  Talk about going green!

The rhizome-buds are generally immune to herbicide applications, making torpedo grass hard to control chemically.  Tilling encourages it. Fire can’t touch it.    Weed-killing fungi have been tried but can’t do the job.  We may be SOL.

Panicum repens runners

Long thin rhizomes running hither and thither.

Panicum repens hollow rhizome

They are hollow gas pipes.

Panicum repens rhizome

To add to the immorality, the rhizomes come in two different forms, sometimes totaling to over 85% of the plant’s biomass.  One form is long, narrow, and able to penetrate the earth submerged, or to run across the surface of the ground.  The long narrow rhizomes have a hollow center, clearly allowing gas exchange deep in the ground or submerged in water.  These rhizomes put the torpedo in torpedo grass, helping it spread and invade like wildfire. The thin rhizomes can be so abundant to form mats 6 inches thick.

The second rhizome type is thick and gnarly, looking like a ginger “root.”   Those who study the species actually call them “ginger root” rhizomes.   These seem to let the species hunker down, store starch, and maybe sit tight until conditions become right for sending out a new infestation of the long thin rhizomes.   Torpedo grass has been documented to “go dormant” under seasonal floodwaters, then resume spreading as water recede.  Alternatively, the rhizomes can make a floating mat.

panicum repens tuber

Ginger root style rhizome on torpedo grass

To sum it all up, torpedo grass is a species you can’t kill, eager to colonize wet places, standing water, scrub, acid soils,  and probably the surface of Mars.    It is armed and dangerous with aggressive imperial rhizomes and with resting food-storing rhizomes.   You can curse it, and sometimes all we’ve got is resignation.    But then again, a super-weed with crazy growpower ought to be good for something.   Does all’s green make a little contribution to carbon dioxide reduction?   Isn’t it good for some biomass purpose?  Maybe as a bioweapon…dice the rhizomes and spew the pieces on the enemy?

Panicum repens goes across mud

 
11 Comments

Posted by on July 12, 2019 in Torpedo Grass, Uncategorized

 

Tags: ,

Plants and Salt

Plants and Salt

Floridians live where plants meet salt.  The ocean’s pretty big, and in other regions salty plants hang out inland at saline seeps,  salt licks, salt flats, and even roadsides where salt trucks fight ice.  Salt-loving plants are called halophytes, although how much any halophyte actually “loves” salt is always a reasonable question.   Many salt-“loving” plants grow happily in un-salty cultivation, red mangroves for instance.   Sometimes the “love” for salt may boil down to tolerance, making a salty habitat where a halophyte competes best.  How plants need, prefer, tolerate, or cope with salt varies.  Unrelated species have evolved salty ways in different fashions.   Always fun to explore.

mangroves from water

Start with mangroves.  Around here we have red, white, and black, all unrelated to each other, and each with its own mechanisms for dealing with seasalt.  Red mangrove holds down its internal salt concentrations by excluding it at the root.   The gated community approach.  Comparatively low internal salt levels might help red mangroves operate their complex system of pumping air to the roots, allowing growth in deep tidal water and suffocating mud. Just speculating on that.

Salty tissues offer protection from bugs and fungi.  Red mangrove, being the least salty of the local mangrove species, seems to have the most fungally infected and bug-eaten leaves of the trio.

red mangrove infected

Red mangrove…low salt = high fungal trouble?

Black mangrove handles salt by secreting it onto the leaf.  Much presumably washes away in rain, although a margarita-rim crust on the underside is fairly persistent.   The pass-through salt system may help hold the internal salt levels down.  In our measurements black mangrove was in the middle of the three saltwise, although there would be variation under different conditions.  The salt crust was left in place for the measurements shown below.*

avicennia salt

Black Mangrove salt crust on leaf underside

White mangrove can secrete salt from glands on the leaves, which are not those two nectar glands on the leaf stalk.   It does not secrete as much as black mangrove, and in our experience does not become salt-encrusted.  Instead, it has somewhat succulent leaves where salt collects internally.    It had by far the highest salt concentration of the species measured.

mangrove salinity graph

Sacrificing entire leaves is costly.  Another way to shed salt is to package it in little bladders,  and then drop or pop them externally.  Waste bags!   Such ability is scattered a little in the coastal plant world, famously in the Amaranth-Chenopod Family, for instance the coastal plant Atriplex, Sea Orach.    Its salt bladders appear mostly on the undersides and margins of young leaves.  They fill and burst, leaving busted bag remnants and salt crud on the underside of the leaf.   As with mangroves, botanists have determined the salty coating to be bug-deterrent.

IMG_8946

Atriplex salt bladder, microscope view

White mangrove gave us a hint already of another way to deal with salt:  succulence.   Seaside plants don’t have much freshwater to flush out salts or to cool evaporatively in the hot beach sun.    Succulence gives salt sequestration, protection from temperature spikes, water storage, and maybe even padding from windy beach conditions.  It must be a “good idea,” because seaside succulents abound: Batis, Cakile (sea rocket), Iva (marsh elder),  Salsola, Scaevola (inkberry), Sesuvium (sea purslane), and more.   Go find a beach plant and, if not a grass, odds are it is succulent.

Several grasses thrive in salty places without succulence.  Some have microscopic salt glands on their foliage.   Virginia Dropseed, a beach and dune species, is a photo-example.  Each salt gland is a short two-celled bump surrounded by four taller bumps called papillae.  Do the papillae protect the glands they surround?

sporobo;us salt gland

Virginia Dropseed grass. Small salt gland (red marker) surrounded by taller papillae, apparent protection for the gland.

 

hydrant

Gland with papillae

Certain species we do not know as salty sometimes thrive in semi-salty places, becoming a wee bit succulent when hanging with salty friends.  A local example is Virginia Creeper.  Does the Creeper thicken as a result of salt exposure, or alternatively, are the thick-leaved Creepers a separate genetically adapted strain, salty ecotypes?    For those with time and inclination it is easy to distinguish the two possibilities.   Grow them in a common garden.  Depending on the species, you can find either case.  I strongly suspect with Virginia Creeper succulence is acclimation by individual plants…my bet is if you take a normal Creeper and grow it in salt it thickens.   Either way, compatible solutes help…let me explain:

Salt sucks.  It draws freshwater by osmosis.  That is why if I drink sea water the brine in my stomach draws water from my surrounding tissues and dehydrates me.  If you put a freshwater plant in saltwater, it wilts because the salt “sucks” the water out.

It is not just salt that does this, but any dissolved material.    One way a plant can fight water theft by saltwater is to accumulate its own internal “salt” (dissolved material) to win the osmotic tug of war with the outside salinity.   These protective “salts” are called compatible solutes.  A well documented heavy user of compatible solutes is the mangrove associate Golden Leather Fern, Acrostichum aureum.  At different points in its life cycle the fern uses different compatible solutes to keep its tissues just a little “saltier” than the surrounding water. Different levels of salt stress can bring forth increasing levels of compatible solutes.

Watch the wilt.  Two VA Creepers. The one on the left from a mangrove swamp. The one on the right from non-salty “normal” situation.   The two placed in saltwater at the same time and photographed over a few hours.  The one from the mangrove swamp tolerated the saltwater.  The other wilts painfully.  CLICK

——————————————————————————————–

*Five leaves of each species were placed in the same volume of tapwater in a blender.
Zero” on the graphs was the level of saltiness measured in a cocoplum grown away from salt.   The units siemens/m reflect electrical conductivity.

 
 

Tags: , , , , ,

Sunburned Tops, Soggy Feet

Sunburned Tops, Soggy Feet

Aquatic Emergent Plants

South Florida is rich in plants growing with their roots submerged at least part of the year, and their tops periscopes above water.   Many unrelated plants have evolved this lifestyle separately.   The convergences and divergences in unrelated species united under one extreme lifestyle makes it all intriguing. And they range the spectrum from fundamentally landlubbers able to withstand temporary flooding to floaters able to withstand temporary stranding.

Pontederia cordata 1

Pickerel weed emergent. By John Bradford.

Emergents come from all corners of the plant world, including ferns and fern allies (Isoetes) to flowering plants from numerous families.   Monocots rule the marsh, with such representaives as arrow arums, arrowheads, cattails, golden clubs, grasses, pickerel weeds, rushes, sedges, and more.

Many emergents imperialize large spaces by subterranean rhizome growth.    You might say with limitless sun and usually unlimited water, two arenas for competition might be nutrients and space.   Some marshes house carpets of a single species, or multiple carpets of multiple species pushin’ and shovin’.  Sometimes competing species intermix, sometimes they occupy pure stands.

Sagittaria graminea.jpg

Sagittaria graminea by John Bradford.

Sunken rhizomes are useful beyond colonization.  Water levels fluctuate seasonally.  Emergents may spend months high and dry where risks include drying, sun, fire, grazing…or the other extreme, flooding.

Sagittaria lancifolia high and dry

Hey—where did the water go?

Apocalyptics like underground refuge.  Some species double down to face dryageddon by making thick starch-storing rhizomes, or tubers such as water chestnuts, chufa, and sagittaria (aka “duck potato”).  We’re ready, come hell or high water!

This photo shows subterranean “be ready” starch storage in Sagittaria.  The dark stained area in the rhizome shows starch storage.  Starch reserves stop abruptly at the leaf bases.

Sagittaria lugols

Sagittaria rhizome sliced to show starch storage.  The starch is stained with purple.

Emergent usually have ductwork called aerenchyma (air-EN-cah mah).   If your feet are under oxygen-starved mud and your top is above water, ventilation shafts help,  “air” channels from leaves to roots. The snorkel analogy is too simplistic, however.   The pipes are not generally open to the outside air.   They usually are more or less closed, sometimes pressurized. Let me explain:

The leaves make oxygen as a waste gas, and require carbon dioxide to make sugar.   The submerged roots do the opposite…they use oxygen for respiration while shedding carbon dioxide.  They make what the leaves need and take in what the leaves shed.   And the reverse prevails up in the leaves.  So it makes sense for  the leaves and roots to trade gases.   A closed pipe system allows the leaves and roots to decontaminate and feed each other…oxygen moving down where needed and carbon dioxide moving up where needed.  Too much outside venting may interfere with such self-contained exchange.

Sagittaria lancifolia aerenchyma longi section

Sagittaria leaf stalk cut lengthwise to show air channels.

Sagittaria lancifolia petiole section2.jpg

Sagitaria leaf stalk cut across to show air channels.

A plant physiologist studying cattail found the carbon dioxide concentration in the aerenchyma to be 10 times the atmospheric concentration. To the foliage that’s a photosynthesis supercharger.   John and I measured carbon dioxide released from cut aerenchyma at the base of a sagittaria.   The technique would necessarily under-estimate the concentration, yet our reading rose to 5683 parts per million,  even higher than the 10-fold increase in cattail, given that the atmospheric carbon dioxide concentration is a bit over 400 parts per million.

leaves in chamber

Okay then, does the leaf aerenchyma pipe oxygen rootward?   We cut off several leaves and inserted their stalks (petioles) into a sealed test chamber with an oxygen sensor. The atmospheric oxygen level outside the chamber as 208,284 parts per million in contrast with  224,389 inside.      Yes, oxygen from the leaf photosynthesis is clearly southbound down the leafstalk air channels.

The species we tested Sagittaria lancifolia has thick leathery leaves you might expect on a desert plant or on a high dry epiphyte, not where water seems unlimited.

Emergents often resemble plants of arid circumstances.   Many have thick resistant blades, or nearly leafless photosynthetic stems, or pencil-shaped leaves with minimal surface area.    Easy to explain at a “hunch” level:  ready for seasonal dry times, robust to relentless marshland sun,   and perhaps root- impaired by suffocation in standing water and waterlogged mud.

The Everglades marsh ecosystem under natural conditions was famously nutrient-limited, most notably phosphorus.   Modern pollution high in phosphorus and other nutrients disrupts the natural species balance.

To turn to the other end of the nutrient spectrum, marshes gobble up unwelcome nitrogen, phosphorus, and other nutrients from sewage effluent.  Visit such water treatment sites as Wakodahatchee or Green Cay wetlands, and see the nutrient-loving species composition of hyper-enriched waters.  Broadleaf arrowhead abounds, true to its reputation as a nutrient vacuum.

whistlers

Nutrient-loving aquatic species at Wakodahatchee Wetlands.

 
 

Pretty Bacteria

Pretty Bacteria

Leptothrix discophora

(Leptothrix means fine hair, referring to thin filamentous bacterial colonies.  Discophora, means “has a disc.” A disc helps attach the bacteria to aquatic substrates.)

John and I today poked into the ecology of a couple aquatic plants, the results not quite ready for prime time.  In the meantime, here is another aquatic.

Sometimes slow shallow waters have a “rainbow” or silvery film on the surface, often resembling a subtle oil slick.    Could be oil.   Poke the slick with a stick.  If it fragments like shattered glass it is probably a colony of Leptothrix bacteria.  A genuine oil slick merges back with itself unshattered.

IMG_8707

The film

Now I’m no microbial expert, and can’t 100 percent guarantee my facts.  I just enjoy knowing these ultra-microscopic life forms,  a taste acquired from Linda Grashoff who lifted bacterial rainbows into the world of art in her book, “They Breathe Iron.”   She sent tips helpful in today’s item.   CLICK to see a great book.  https://scienceandartpress.com/

Leptothrix bacteria form tiny hairlike branched chains enclosed in a sticky sheath.   Think of a translucent garden hose holding a string of beans so minute as to be challenging to examine with a good microscope.

Leptothrix microscope

Under the microscope.  The hairs are Leptothrix colonies in their sheath.

The sheath-bound chains can accumulate as a film on the water surface, or may stick to submerged sticks or stones.    The bacteria have a complex nutritional cycle involving organic matter, and iron and manganese.  The bacteria oxidize (you might say “rust”) these metals and adorn their sheath with metal nanoparticles.   The resulting colors vary with the thickness of the bacterial film and with the relative amounts of iron, multicolored, and manganese, silvery.

IMG_8728.JPG

Leptothrix is similar to the more famous and useful Sphaerotilus bacteria that contribute to the stringy “floc” during secondary sewage treatment, where they help the organic components in sewage.  Somebody’s got to do it.

Leptothrix in Winogradsky.jpg

Given that Leptothrix thrives on organically enriched water and iron,  it possible to “cultivate” the bacteria in a cylindric glass vase called a Winogradsky column, filling the column with waterlogged pond mud covered with pond water.   For iron I used Feosol iron dietary supplement pills. The vase came from Dollartree, the world’s greatest source of inexpensive botanical “labware.”

wino

Winogradsky column, with Leptothrix (not visible in this photo) afloat on top.

 

Dig in deeper:  Dyer, Betsey D.  A Field Guide to Bacteria. Ix + 355 p.  Cornell University Press, Ithaca, NY. 2003.

Linda’s Blog  CLICK  https://lindagrashoff.wordpress.com/

 
2 Comments

Posted by on June 21, 2019 in Leptothrix, Uncategorized

 

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.

————————————————-

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.

 

Tags: , , , ,

 
%d bloggers like this: