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Canadian Horseweed Does the Twist

15 Jan

Conyza canadensis

Asteraceae

Today’s fieldtrip aborted…due to tornado warning? Ya gotta be kiddin me! A freakin’ twister. So my afternoon turned toward a different direction…looking into the recent listing of glyphosate (RoundUp) as a probable human carcinogen.   I’m not expressing opinions here other than, “well ain’t that interesting.”  This nice friendly blog is not for un-fun head-hurting controversy, so let’s merely ask how does RoundUp interface with a twister.

It is astonishing that weeds can evolve resistance to herbicides, survival of the fittest!   A lot have turned RoundUp-resistant, with one of the most resistant of the resistant being a native weed that’s everywhere and still overlooked…Canadian Horseweed. When I say everywhere, I mean everywhere: in every vacant lot, in every Florida county, in every U.S. state (yes, Alaska and Hawaii), in every Canadian province or nearly so, and almost surely on every continent except Antarctica. Yet who’d know it on sight? It looks like “weed,” although up close the flowerheads have beauty.

conyza far

All photos today by John Bradford

RoundUp resistance has turned up in this species across the U.S. and beyond. And that reveals some weird observations and questions.   First up, if resistance is so widespread geographically, did it evolve once and spread, or did it evolve multiple times in many places?  I don’t know but will vote for “lots of times.”   Convergent evolution at work.

The plot thickens.   Anybody attuned to GMO controversies dreads genetically introduced RoundUp resistance genes spreading from crops to weeds, making Superduperweeds.   But look what happened here…the weed did not receive resistance from a GMO crop, but rather cooked it up on its own.

And then it transferred resistance to another species, not crop to weed, but weed to weed by interpollination. Conyza canadensis shared resistance by hybridizing with Conyza ramosissima. The hybrids are more RoundUp resistant than the parent.

And there’s more.   How often do non-native invasives breed with native species?   Examples are few,  but there are hints in the literature of our native C. canadensis mixing genes with C. bonariensis, an invasive species called Asthmaweed here in Florida.

conyza side

So funny how one thing leads to another with strange twists. RoundUp resistance evolving in Canadian Horseweed reveals interspecific transfer of the resistance gene (but not as feared, from a GMO crop!). Attention to this brings up another fear come true: probable genetic pollution of a native by an invasive, although in weeds where nobody would notice or care.

conyza flower

 
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Posted by on January 15, 2016 in Canadian Horseweed, Uncategorized

 

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Trojan Horse Herbicides

08 Sep

Red Mangrove (Rhizophora mangle) (CLICK for nice Gigapan Red Mangrove by John Bradford added subsequent to posting this blog)

Black Mangrove (Avicennia germinans)

White Mangrove (Laguncularia racemosa)

Toxic “Algae” (Microcystis aeruginosa)

John and George today worked on our tans portaging camera gear around the Kiplinger Natural Area on the St. Lucie River by Stuart.  John seized the day to capture Gigapan photos of the river shore.

Gigapan photos allow viewers to pan around and to zoom in on details.  Try it after CLICKING HERE to cyber-visit the river.

We had Mangroves on our mind, and they did not look healthy.  The shore is lined with a species jumble, including Brazilian Peppers, and many mangroves (especially red mangroves) are dead or visibly unhealthy.    (As pointed out in the commentary below,  the dead trees in the gigapan seem to be entirely or mostly Brazilian Pepper, although in the vicinity there are miserable mangroves too.  The mangroves at this site look decidedly less healthy than those directly on the Intracoastal where I spend a lot of time.  I have re-edited this post post-publication to reflect the fact that most of the dead trees are not mangroves.  The main point is the water contamination, so read on.)

Now you might say, justifiably, that 10 boat-miles upstream from the St. Lucie Inlet might be marginal mangrove habitat to begin with.  (What killed the Brazilian Peppers is interesting too.)  A possible reason mangroves to be so far upstream is increased salinity due to reduced freshwater flow from upstream thanks to some mix of water-control activities, dams and spillways,  diversion, droughty times, and altered land use patterns. (Or maybe not.)  Maybe that pulls the mangrove yo-yo upstream.

Now, if increased salinity crept up the St. Lucie River over some years, or even if it didn’t, the massive summer releases from Lake Okeechobee push the other way.  The lakewater this summer reduced salinity to almost zero even near the Inlet.  The usually brackish lower river was freshwater.

And that would be freshwater overloaded with nutrients, with nutrient-fed “Algae” (mostly Cyanobacteria), toxins from those Cyanobacteria, sediments, and whatever else enters the Lake and the River from agriculture and suburbia.

Yesterday the river water was dark, opaque, stinky, and lifeless.   A boat went by and you could smell its wake splashing on the marly shore where we saw no Fiddler Crabs, despite John photographing their abundance at exactly the same site not long ago in this very blog.  CLICK to see missing crabs.

I wonder if the missing crabs used to benefit the mangroves by churning and  aerating that watery soil?

(Come to think of it, there weren’t even any mosquitoes.)

Most local readers probably know about the Lake Okeechobee flush disaster this summer and other years.     No need to re-beat that dead horse in general terms.  But specifically, what about the dominant riverbank woody vegetation—those red, black, and white mangroves?

Known or suspected causes of mangrove decline, in addition to storms and freezes, include salinity changes,  excess sediments, excess nutrients, and herbicide contamination.  These all arrive in water from Lake O, on top of everyday watershed abuses.

The last culprit in the list is subtle.  Herbicides?  Studies of mangrove dieback in Australia pinpointed herbicide river contamination as a mangrove-killer, especially the herbicide Diuron, which has an extra- special vengeance for the genus Avicennia (Black Mangroves).

Diuron is toxic false-fertilizer. It kills mangroves, and yep, we have it in local waters.

Diuron is toxic false-fertilizer. It kills mangroves, and yep, we have it in local waters.

So then, what about Diuron in the St. Lucie River?  Yes, in the notes below is a link to a dated but still-relevant USGS study of pesticides in the St. Lucie River.  The top five pesticides detected were all herbicides, including Diuron, as well as our traditional favorite lawn-weedkiller Atrazine and others.  Diuron is a Sneaky Pete herbicide.  Plants take up natural urea (or the ammonia soil microbes degrade it into).  Diuron is a urea mimic, water soluble, a Trojan Horse false-fertilizer similar to urea but with chlorinated timebombs built into the molecule.

The concentrations were “low,” but how low is low enough, especially in light of the gang-attack of several different herbicides, the probability that concentrations are higher in sediments than in the tested water,  that there is more development now than in the 90’s, and especially that those pulses of agricultural/suburban-lawn  contaminated lake water may have higher pesticide loads than “nice” water on a good day.

Can I say that Diuron killed the mangroves?  No.  Can I say that the Lake O water did it?  No.  But there’s something rotten in the State of Denmark.  Salinity volatility, crud,  N and P in gobs,  natural bacterial toxins,  and the fruits of modern chemistry all attacking a trio of mangrove species, each with specialized and delicate physiology with respect to salt, nutrients,  water transport and the soil ecosystem.

Some time ago in this blog we discussed the reproduction of Black Mangroves.  They drop their bare embryos directly from the fruit into the water.  CLICK

Yep, right into the Diuron-laced stinkwater sloshing around their snorkel roots jutting up to sustain life through the toxic sediment mud where the crabs ain’t no more.

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Notes:

USGS report on pesticides in St. Lucie River http://fl.water.usgs.gov/PDF_files/wri02_4304_lietz.pdf

Used the same item for both my blogs this week.  Don’t tell anyone.

 
16 Comments

Posted by on September 8, 2013 in Black Mangrove, Red Mangroves, Toxic Algae, White Mangroves

 

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Sea Blite and Castaway Plight

29 Jun

Sea Blite

Suaeda linearis

Amaranthaceae (Chenopodiaceae)

John, I TOLD you to turn right.

John, I TOLD you to turn right.

Yesterday John and George mired the car hopelessly in the seaside sand lost in the remote reaches of the Hobe Sound National Refuge, all in a day’s work for fearless adventurers.   It happened right as I said, “that sand looks firm.”  We became stranded castaways deep in a mangrove jungle unvisited by humans since Jonathan Dickinson.  While we stressed over who might find our buzzard-picked remains, we kept our spirits up by exploring the salty-marly mangrove lowland behind the dunes and singing marching songs from the Boer War.  We looked for esculent native plants to mitigate our stranded plight.  There wasn’t much to hunt and gather, but Black Mangrove was lovely in flower, and no, that wasn’t a skunk, it was White Stopper.

Our destitution gave us time to ponder convergent evolution.  (That is when unrelated species develop similarities due to similar adaptations.  Sharks and Porpoises are not related but they look similar.)  We saw no sharks nor porpoises, but we did see how salty-place plants have a convergent tendency toward succulent leaves that look like fingers.  The fat-finger-foliage species include Batis maritima (Saltwort, Batidaceae),  Salsola kali (Amaranthaceae), Sesuvium portulacastrum (Sea-Purslane, Aizoaceae), Salicornia bigelovii (Glasswort, Amaranthaceae), and Suaeda linearis (Sea Blite, Amaranthaceae).

Yes, the foliar similarities can confuse identification.  And yes, they confuse common names.  The common names for these species are intertwined and contrived.  For example, Batis maritima and Salsola kali (and undoubtedly others) get called “Saltwort,” hence the silly misleading name “Russian Thistle” to differentiate Salsola.  My personal outlook—never get too fixated on the English names for non-prominent plants.

The main succulent finger species yesterday was Suaeda linearis,  representing  the mostly saline genus Suaeda which has over 100 species.   As is often true of coastal species, the distribution is wider than you think.  Suaeda  linearis extends from Maine to Mexico and southward.  Such species keep us from getting too hung up on latitude.

Suaeda linearis (JB)

Suaeda linearis (JB)

Suaedas inhabit saline desert areas in North Africa, where  Beduins burn the foliage to obtain soda-ash (sodium carbonate)  for laundering,  dying clothing, and fine-tuning the pH in their pools.  And speaking of burning  Suaeda, North Africans burn the plants also to generate smoke for asthma relief.  Suaeda is an ancient Arabic name.

Close-up (JB)

Close-up (JB)

Closer to home, Native North Americans appreciated the seeds as a staple grain, which was a comfort to John and me as we despaired of rescue yesterday.  As we roasted fiddler crabs on burning Suaeda and tried to invent a solar desalination still using our shoes, John suddenly remembered we had cell phones.  The miracle of Verizon brought a nice man named Bill with a big truck to yank us out of our sandy Hell to explore and blog another day.

[Note—that isn’t really John’s car. His car isn’t that cool.  But we did get quagmired and rescued deep in the jungle.]

 
6 Comments

Posted by on June 29, 2013 in Sea Blite

 

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Naked Embryos and Dead Man’s Fingers

18 Nov

Black Mangrove

Avicennia germinans

Verbenaceae

This week’s Friday field trip by John and George got nuked by a combination of work obligations, rain, and car trouble.  With reference to the last-mentioned, this post was written in the commodious Napleton Nissan/Kia Service lounge in Riviera Beach, with complimentary coffee and People Magazine.  So we’ll step back in time just a couple weeks.  Black Mangrove (Avicennia germinans) surprised us by practicing dispersal in massive quantities by bare naked embryos.  We found thousands of them in the tidal wash on the beach at the Hobe Sound Wildlife Refuge across the Intracoastal from Tiger Woods’s spread.  Everybody knows that flowering plants usually disperse as fruits or as seeds, but as exposed embryos?  In saltwater?  Yes.  And some were already rooting on shore, making it clear how you wind up with extensive stands of Black Mangrove.

Black Mangrove embryo castaways on the beach (photo by JB)

Googlization reveals this peculiarity to be old hat to mangrove cognoscenti, even being the basis for the specific epithet “germinans.”  But we’re nobody’s cognoscenti, thus our happy surprise at the little embryonic nudists.  It is also old hat to some plant propagators who soak Avicennia fruits to liberate the embryos for sowin’ and growin’.  By the way, the name Black Mangroves refers to the dark-colored wood.

Embryos from Avicennia species can remain viable over 6 months submerged in sea water and can float alive at least 50 km, although most dispersal is local.  The embryos are large, fleshy, and well provisioned before release.  They look like the innards from a giant lima bean.

Having escaped their fruits and seeds, and having enlarged, they  are in a sense prematurely germinated, and in this way vaguely resemble the precocious seedlings dropping from the unrelated Red Mangroves with a big prematurely sprouted embryonic root sticking out of the persistent fruit covering while still on the mama tree.

Inquiring minds may now ask, well, what about the third Musketeer,  White Mangrove?  Its fruits disperse in the traditional fashion—intact—but they have some “pregermination” going on too, as the seeds can sprout inside the fruits during dispersal.  This shared tendency is an interesting tidbit of convergent evolution where three different and unrelated species have all adopted premature germination, in different forms, to meet the challenge of saltwater-drift dispersal.

Dead man’s fingers (photo by JB)

Anyone with much experience hanging around docks has encountered spooky black gnarly “dead man’s fingers” rising vertically among Black Mangroves.    More convincingly than Bald Cypress “pseudo- pneumatophores,”   Black Mangrove pneumatophores have obvious adaptations as root snorkels.

The fingers are filled with spongy tissue suitable for gas exchange.  The finger lengths adjust to the need for air, and lenticels (breathing pores) on the fingers reportedly open and close in response to environmental conditions.

 

 

 

 

 
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Posted by on November 18, 2011 in Black Mangrove

 

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Love Vine

29 Oct

Love Vine

Cassytha filiformis

Lauraceae

Bee on Conradina (Photo by JB)

John and George explored the Hobe Sound National Wildlife Refuge on the shore of the Intracoastal yesterday, encountering millions of Black Mangrove embryos in the beach debris, some of them taking root.  This was interesting because the dispersal agents are tough, food-laden bare naked embryos without benefit of enclosure in fruit or seed.    We saw Dicerandra immaculata in full bloom left over apparently from a reintroduction effort, enjoyed a bee working over a False-Rosemary (Conradina grandiflora) systematically flower by flower, and encountered a pixieland of mushrooms on the scrubby sugar sand dunes.  

The most imposing and conspicuous (fully) living thing there was the Love Vine draped over trees and shrubs, so we must give it its due.  Love Vine is a nearly leafless scrub-loving parasite resembling orange-tinted spaghetti noodles overwhelming its scrubby shrubby victims.  The botanical name Cassytha comes from Aramaic for “tangled wisp of hair.”  The old name “Woe Vine” fits pretty well too.

To remove a common point of confusion, Love Vine and Dodder look alike but are unrelated examples of convergent evolution.   Dodders are species of the genus Cuscuta in the Morning Glory Family, Convolvulaceae.  Several species live in Florida, with a handful of species in our immediate area.    Although resembling Love Vine, they are far less common and tend to specialize on herbaceous victims as opposed to Love Vine’s preference for bigger prey.

Love Vine (image found on John’s camera after he dropped it fleeing into the woods)

Love Vine (Cassytha filiformis) is a member of the Cinnamon Family, Lauraceae.  Love Vine differs from Dodder by having fleshy drupes (vs. dry capsular) fruits, and by having a feature characteristic of Lauraceae: anthers that open by flaps instead of by the usual slits.   You can see this with a hand lens.   A suggestible observer might sniff the membership of Love Vine in the Lauraceae by a faint spiciness when crushed.   Love Vine has its flower parts in multiples of three, as opposed to multiples of five in Dodder.

Our species, one of about 20 in Cassytha, is worldwide in warm-climate coastal areas.  Apparently the fleshy fruits disperse in part by floating, aided undoubtedly by birds and by storms.

The adaptations of Love Vine for parasitism are profound.  The vine adheres to its host with “suckers” (haustoria) that look like something on a space-alien octopus. 

Love Vine haustoria on oak leaf (photo by JB).

You might think it just sits there and sucks, but the invasion runs deeper.   Tissue from the sucker enters the host and spreads into the hosts cambium (living region just under the bark) and/or phloem (sugar-conducting tissue immediately outside the cambium).  It is never a great idea for a parasite to kills its host.  Although Love Vinosis is sometimes fatal eventually, the attack has a built-in host-sparing restraint.  The parasitic tissue invades the cell walls of its host and draws nutrients out of the host cells across the cell membranes, but the parasitic tissue never actually breaks the host’s cell membranes, thus leaving the host cells alive to keep on feeding.  The recurring idea of harnessing Love Vine as a biocontrol against unwelcome plants may be hobbled by the comparatively nature of Love Vine’s attack. 

On a subcellular level, the xylem (water-conducting) tissues in the parasitic suckers have structures often called “graniferous tracheary elements.”  In plain English, the plumbing at the intake zone has a pressure valve involving tiny granules whose function seems to be to control the stream of incoming stolen sap.    The distribution and roles of these poorly known structures need research.

Around the globe, Love Vine has accumulated numerous uses, ranging from body decoration, to medications, to hair promoter, to potential modern cancer therapy.   As is so often true, the plant contains toxic alkaloids, yet is on the menu in some cultures.    And of course, Love Vine is the active ingredient in love potions.    Happy Halloween.

 
4 Comments

Posted by on October 29, 2011 in Love Vine

 

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