Treasure Coast Natives

Argemone mexicana

(Argemone is an ancient Greek name for a similar plant.)

Papaveraceae, the Poppy Family

The trouble with species and actors known for one thing is that they become typecast at the expense of “other things.”  So it is for the biochemical factory known as Mexican Poppy. You’d be challenged to find a plant with a thicker pharmacological portfolio, but little else is known about it.    Despite the deficiency, let’s explore the “other things” first.

Native to Florida and Tropical America, Mexican Poppy is a colorful and bioactive invasive annual in the warm-climate Old World, prominently so in Africa and India, where it has woven itself into local cultures.   Its splendid yellow flowers and white-patterned leaves plus dubious medicinal benefits have created a market for the seeds.

The plant loves uncrowded disturbed situations, popping up socially distanced on bare soil.  Its basic strategy is fast growth to seed production in nasty sun-baked places free of competitors.   Down goes a quick taproot and up come those gorgeous flowers and prickly pods before neighbors crowd in.  And should that threaten, well, Mexican Poppy can poison surrounding plants.   This diminishes its popularity in agricultural fields, except sometimes for suppressing other weeds.   Herbivores tend to take a raincheck, since the leaves are painfully prickly and the plant is a cauldron of bioactive chemicals, many of them in yellow sticky sap.

Botanist M. Kaul studied the floral biology in India in the 1960s.  The vivid showiness of the blossoms may be largely wasted, given that they are in large part self-pollinating, no big surprise in a pioneering weed.  Pollen releases before the flowers open, although visiting insects probably add cross-pollination when the flowers are open.   Oddly, the flowers have a second, post-opening opportunity for self-pollination.  While open the petals collect pollen like sugar on a spoon, then when the flowers close the rising petals lift the pollen up to the pollen-receiving stigma.  Reproductive assurance!    Dr. Kaul’s sketch of what happens is below:

An aspect of the pollination that I’ve never encountered before, perhaps revealing bone-headed ignorance, is that pollen fertility increases at the height of the flowering season.  This pattern was consistent across many flowers at many localities in India.  Could it be that during the off-season more reliance on self-pollination allows reliance on less-fertile pollen, with an investment in the “good stuff” saved for a precious peak-season insect agents?  Or a boring alternative is that poor weather in the off-season interferes with pollen quality. This should be checked out here in native Florida, and I might try.

The seeds look like mustard seeds and similarly, contain oil.   They have been mixed as a cheap extender to mustard seeds, with fatal consequences when used in cooking.  The oil serves less dangerously as lamp fuel and has been investigated as a source of biodiesel growable where other crops won’t grow.

Name any human medical need from malaria to male contraception.   Mexican Poppy has been applied for or suspected as potentially useful for a hundred problems.  (Forget trying anything—it is dangerously toxic.)  Among the more prevalent applications are to cure worms, to fight leprosy, and  to counter skin conditions.   The ancient Greeks used related species to treat cataracts.  Morphine comes from poppies. Does Mexican Poppy contain morphine?  Not to my knowledge, but it does contains chemicals animal-tested for morphine-withdrawal.  Modern medicine is perpetually interested in cell-killing (cytotoxic) compounds to treat tumors.   A wart is a (benign) tumor, and historical uses of Mexican Poppy to kill warts signals potentially useful cytotoxicity.

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Pseudognaphalium obtusifolium

Lepus sylvaticus

Asteraceae

Can you imagine a “child of today” out behind his mother’s she-shed with pals puffing surreptitiously on a corncob pipe filled with Rabbit-Tobacco?    As a baby boomer,  I regrettably missed that rite of passage;  pals of my age were more likely to puff “Wacky Tobacky.”  But go back one more generation,  and you could readily find kids smoking a genuine “weed,” Rabbit-Tobacco.   My father, who grew up in Depression-era Alachua County,  upon encountering RT a few years ago while we were walking near Vero Beach, reminisced at age almost-90 about smoking Rabbit-Tobacco in the1930s.  Too bad he did not have a pipe in his pocket! The experience was not a long-term habit or way of life, more like something daring kids tried once or twice to be grown-up.    After all, everybody smoked in those days. Here is a recollection on all that: put this in your pipe and smoke it

Rabbit-Tobacco is related to Artichokes, and not to Lucky Strikes.   So why smoke it?   Wellll,  it has a gentle pleasing fragrance.    And soft dry pliant leaves cover its stem.  And It crushes into a pipe and burns nicely.   Rabbit-Tobacco does sort of invite smoking.  Which I am not advocating. 

All of that explains “Tobacco” in the name.  For years I assumed the “Rabbit” part to have come simply from the plant’s habitat shared with bunnies.   But a dive into the Internet today reveals alternative realities.   The species traces back prominently among American Indigenous peoples, some of whom allegedly connected it legendarily with rabbits long before boys smoked behind the barn.  Or, for another explanation, the round white flower heads look like bunny butts. (Personally I doubt that cuddly explanation.)

What interests did people long ago have with this plant?   Even in the ancient Old World, similar close relatives served as remedies.  Rabbit-Tobacco smoke served prehistoric and more-recent Americans for purposes beyond smoking in pipes.  Ancient civilizations burned it like incense for smoky ceremonies, and as an “inhaler” for respiratory discomforts.    One of my favorite traditional uses was to stuff it into pillows for sweet dreams.  Gotta try it!   Teas were made from the foliage as well.

The attractive cut stems are long-lasting, or should I say ever-lasting, as this species and its relatives are called “ever-lastings.”   That’s useful in a vase, where the severed stems continue to perfume the air.   The fragrance does not waft forth evenly over time.  Something variable—temperature?  humidity?—causes the emanations to wax and wane. Such plants waver ethereally on the border between life and death, as a clue to their spiritual symbolism.

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Today I accompanied my wife Donna to Boynton Beach where she had work to do while I had botanical fun in the Hypoluxo Scrub Natural Area.   My intent was to examine oak trees, but became distracted by the fairy forest of ground-dwelling lichens.  Sorting out the local species seems a little boring and pedantic, as does re-re-repeating internet attention to the endangered “perforate cladonia,”  or lecturing on “lichens 101” (moss-alga combo, extreme habitat tolerances, sensitive to air pollution, yada yada yada).  The fragility of lichens complicates the application of prescribed burns and mechanical maintenance in scrubby habitats, although pockets of lichens tend to survive passing fires, thanks largely to the natural firebreaks of open sandy areas.  Today  let’s fool around with some less “internet-ized” aspects of soil-dwelling lichens.  If you’d like to learn the basics about them, click here.

The textbook definition of a lichen is the symbiotic marriage of a fungus and alga.  Botanists have long known of greater complexities, such as involving two species of fungi.   Even better, bacteria lurking in lichens appeared in early 20^th Century microscopes. Appreciation of their involvement in the lichen multispecies partnership, however,  has gained modern currency thanks to molecular techniques.  The bacteria are abundant, varied, and integrated into the lichen’s machinery, although their contributions to nutrient cycling, protection, and hormone production are just emerging.  

It seems that the predominant bacteria in the types of “reindeer” lichens in Florida scrub are Alphoproteobacteria, a broad diversified group often involved symbiotically with other organisms.  In 20-20 hindsight, it does seem that the old classroom dogma “the alga provides the sugars—the fungus does the rest” is too simplistic.   After all, bacteria are players within me too, and with both lichens and my tummy, it’s sometimes unclear as to which bacteria are beneficial, which are mere tagalongs, and which are bad company.  

An irksome question is the “purpose” of the scarlet coloration on the branch tips of species of “British Soldier” type lichens in the genus Cladonia.  The red zones are the fungus’s spore-making organs called apothecia (app-oh-THEEK-ee-ah).    Nobody knows to what extent lichens even use fungal spores for reproduction, given that being a combination organism, most lichen reproduction is by tiny flakes where bits of the alga and fungus flake off hand in hand.   That said, the spores matter at some level, and are the only chance for fungal sexuality.   So why do those spore-making apothecia have such shocking red tips?  Good luck finding a trustworthy answer on the Internet.  The obvious explanations each have one or more flaws:

1. The red tips attract insects to help disperse the spores (or help disperse the tiny adjacent two-species-flakes). Too bad combing the internet for any hint of insect visitors in text or photos comes up dry. Nothing! 

2.  The red tips are warning coloration.  “Don’t eat me because I’m poison.”   Some mammals, such as reindeer, eat lichens.   Maybe Rudolf got his red tip from lichen DNA.  The lichens with red tips are toxic, and the red pigment, rhodocladonic acid, is nasty.   Thus warning coloration seems plausible except for this possible deal-breaker: other than primates, mammals generally have poor color vision, as Piotr Gąsiorowski pointed out discussing the warning coloration idea on a lichen blog.    So much for that,  unless the red colors deter arthropod herbivores, which do have good color vision,  such as in insects visiting colorful pretty flowers.  Mite damage reportedly can increase production of rhodocladonic acid. 

(Note added after posting: After this blog was posted, Dr. Gabriele Gheza, lichen expert and author of Cladonia blog Cladonarium) e-mailed his informed views on the different hypotheses. Although he has reservations about how important mites are in the role of the red tips as such, he sent a link (Click) to the reference about mites inducing rhodocladonic acid…in parts of Cladonia lichens that are not red.)

 Staving off mites and other tiny varmints doesn’t pass my personal gut-feeling test.  Of course, colorful warnings aside, poisons may protect the lichens from color-blind munchers.  I  doubt that’s what the redness is all about nonetheless.

3. The red tips are sun protection.    It seems odd that “sunscreen” would be so precisely localized on branch tips, but maybe protecting the sexual spore-bearing regions there prevents mutations.   Why would sunscreen be bright eye-catching scarlet? I dunno.   In other species related to the red-tip-types, the tips are merely brownish, pinkish, or purplish.  Other living things, for example “red tip” cocoplum,  shoebutton ardisia,  Christmas lichens,  red mushrooms,  some sphagnums, and some bacteria have reddish pigments interpretable as sun protection.  Lichen pigments, even when not fire engine red,  have been demonstrated to protect sun-sensitive lichen tissues.    So, if I’d have to bet, I place my money (but not much) on sun protection.    

Cyanthillium cinereum

Asteraceae

There’s a common little wildflower around, kinda pretty, kinda subtle.  You’d perhaps never guess it isn’t native, given that it seems so comfortably “at home” in Florida woodlands while never to my knowledge becoming rampant, rude, and ruderal.  Little Ironweed is native to Tropical Asia.

I wonder if the migration of this tropical species northward in the Americas is related to Global Warming.   The seeds are readily dispersed by wind,   so its migration is more likely controlled by conditions where it lands than by ability to get there.  Check out this apparent progression based on a quick & dirty survey of museum specimens and literature reports:

Indigenous to SE Asia: forever

Jamaica: 1882

Widespread in Caribbean: 1960s

Miami and the Keys: 1961-1968 many collections (as though novel)

Palm Beach County (Palm Beach Junior College Campus—Panther Proud!): 1968

Brevard County  (north of prior record):  1974.  This is the present known reliably identified northern limit.

There are current reports in Georgia on inaturalist, but of dubious accuracy.

Back in its area of origin, Little Ironweed has an unusual use:  as a “quit smoking” aid.  Studies aimed at getting to the bottom of this application and why it works have found two relevant points of knowledge:

1. The weed contains nicotine.

2. It numbs the tongue.

(Do not try it!  The plant contains bioactive compounds beyond nicotine, and may not be safe!)

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Thespesia populnea

(Thespesios in Greek means wonderfully divine, perhaps because the wood was used for carving religious icons.  Populnea reflects the resemblance of the leaves to a Poplar tree.)

Malvaceae

In sunny coastal spots around South Florida, not to mention around much of the tropical world, thrives the Portia Tree,  Milo to others.   Around here it is a sort of a weed, actually a Category I invasive exotic.  Generally speaking, plants with fruits or seeds transported by ocean currents get around.  

It is not 100% clear where the tree is truly native, evidently around the Indian Ocean, where its uses in medicine are ancient.   There are mysterious archaeological remains of it in a cave on the island of Aitutaki literally in the middle of the Pacific Ocean dating to 1200-1400 AD, long before European sailing ships came over the horizon.   Did it float there from Asia?  Conceivable, but still somebody took it into that cave.    Archaeologists believe pre-Europeans brought the plant and others across the tropical Pacific, including Hawaii.    Quite a feat!   Our tree appears in Hawaiian legends of origins.  Why did they bring it?

The Hibiscus Family has fiber species:  caesarweed, cotton, Indian-hemp, kenaf, and, you guessed it, Portia Tree.  And it gets better still.  Ancient uses also included edible leaves, quick-growing wood,  medicines, and dyes.  There remains modern interest in it as a natural fabric dye. By the way, the flowers are pretty too, and change from yellow to orangish or reddish late in the day.

Those floating fruits and seeds have hollow spaces for buoyancy, and contain oodles of oil.  There’s so much oil Portia Tree is a candidate source for biodiesel, especially given its ability to grow fast and furious in salty soils otherwise not very useful for agriculture.    Compromised salty soils are expanding.

The gorgeous wood deserves a special nod.   Prehistoric and historic people made canoes from it.  Modern (and no doubt ancient) crafters value(d) its gnarly patterns and rusty-reddish heartwood for carving and woodturning, especially bowls.  You can buy them in Honolulu.   I’ve always been fascinated by the idea of finding uses for the limitless Florida invasive exotic woods, you know…Brazilian Pepper, Casuarina, Earleaf Acacia, Melaleuca, and more.   Guilt-free woods galore!

Sophora tomentosa

Fabaceae

Every South Florida gardener landscaping with native species* soon encounters the pretty legume shrub necklace pod*, with bright yellow pea-type flowers and pods resembling the snake who ate oranges.

Not a path I’m going to follow, but some readers may be interested in the complex bioactive chemistry and ancient to modern medicinal roles for the genus Sophora, having about 70 species around the world.    All that is easily Googled, and for now set aside.

What’s more interesting is how Sophora tomentosa achieved its global transoceanic distribution.    Around the world, its favored habitats are salty shores, such as beach dunes and other tough habitats adjacent to the sea from Florida to Africa, Japan, and Australia.    In order to colonize new shores as a lonesome castaway (with no pollination partner),  in addition to normal insect pollination, it also has self-pollination as well as cloning requiring no pollination at all.  Reproduction is assured, no matter where a seed washes up and grows.

The seeds are within indestructible lifeboats.  The fruit segments break apart, each segment containing one seed.  The outer layers of the fruit segment surrounding the seed are thick, tougher than armor, and presumably buoyant.  (Also, the seed itself has a small airspace between its two seed leaves.)  When the pod segment the seed within falls in saltwater, or when the tides and waves lift them from the maritime sands, off they go to repopulate seashores around the world!    The longest-recorded saltwater float time followed by germination is 104 days. (Perhaps much longer occurs… 104 days sounds like somebody said, “okay, enough is enough, stop the experiment and see if they sprout.”) 

You can find sprouted necklace pod segments in beach debris.    Do they sprout in the drink and hit the shore already germinated?   Possible,  but my guess, no.  Do the segment-seed units somehow “sense” coming ashore?    Nobody has ever determined that, but I’m betting on it.   There have been some experiments involving S. tomentosa germination, but not asking the interesting question, “what wakes up the seeds on the beach after a long ocean float trip?”   Maybe freshwater rain soaking in?  Microbes and fungi able to grow on shore but not in the ocean?  Or, as tree expert Ray Caranci speculated in conversation yesterday, maybe going from the stable ocean temperatures to fluctuating extremes on land?  

Could the answer merely be wave action scraping the little travelers on the sand?  Like most legume seeds, artificially damaging the seedcoat…”scarification”…does boost germination, but a problem with that explanation is that the seed to scrape is encased in that thick pod-segment armor.   Good luck scratching its seed coat.  

I think I see some low-budget experiments to try. First we need a bucket of seawater and 105 days.

*A note on nativity.   There are two formal varieties of S. tomentosa around town.  Variety occidentalis has fuzzy mature leaves, is in the landscaping trade, is reputedly not native to Florida. Variety truncata has unfuzzy mature leaves and is regarded as native.  Given, however, the ocean-current distribution of this worldwide species, I wonder if Mother Nature may be a little more complex than the textbook version.

Happy New Year.

(On Strangler Figs)

Time to speculate:

Butterflies often use toxic plants as caterpillar hosts.  The larvae take up poisons from the host plant and become protectively poisonous, the safety shield carrying over into adulthood.  Monarchs feed on milkweeds able to stop a predator’s heart.   Pipevine and the Polydamas Swallowtails who eat them kill cells.   Zebra Longwings obtain cyanide from their passionvine.   Could go on, but we all get the point.   But now comes a minor mystery, the Ruddy Daggerwing Butterfly and Ficus.

For most common creatures the Internet reveals a ton of research.     But try that for the mysterious Ruddy Daggerwing Butterfly.  Yes, there are tidbits, but what the knowledge-seeker learns quickly it is how under-studied this beautiful creature is, at least via normal Internet snooping.   Maybe there’s deep research out there in dusty tomes or secret catacombs.

Its larval hosts are members of the fig genus, Ficus.   At least toward the northern part of the butterfly’s small range, mainly Strangler Fig.    The Daggerwing’s distribution and that of the Strangler Fig are virtually the same.

Do figs pass poisons to Ruddy Daggerwing caterpillars like those milkweeds, pipevines, and passionvines do to their caterpillar partners?  Ficus drips milky sap when broken, and in a general sense we don’t trust milky sap.   Also, you don’t often see much insect damage on Strangler Fig foliage.    But specifically, is there something nasty, and what might it be?

There might be something very insecticidal,  and to go farther we need some context on cholinesterase inhibitors.   Cholinesterase (colon-ES-ter-aze)  is a key enzyme in an insect’s and my nervous system.  Inhibit cholinesterase, and you inhibit nerve function.     They are central to today’s story.

Most of the late 20^th Century insecticides were cholinesterase inhibitors. So are certain military “nerve agents.” They kill bugs and humans.

Most attention in treating Alzheimers centers on cholinesterase inhibitors. They might be useful to humans when properly harnessed.

Most recent attention to the biochemistry of Ficus centers on its cholinesterase inhibitors in relation to potential Alzheimers treatments.

So then, it looks at a glance  that perhaps the Ruddy Daggerwing can tolerate and sequester the fig’s cholinesterase inhibitors as its own borrowed secret weapon.

Sounds good to me.  All that’s missing is evidence.

Boehmeria cylindrica

(G.R. Boehmer was an 18^th Century German physician and expert on everything. Cylindrica refers to the cylindric flower clusters.)

Urticaceae, the Nettle Family

Across eastern North America and beyond, including all over Florida, there grows a shy wildflower capable of subtle beauty at its best moments.  In flower presently, False-Nettle resembles the stinging nettles familiar to itchy victims with more-northern roots, and is related, but False-Nettle gives you no pain.    (We do have some stinging nettles around here, but scarce.)  The favored habitats are low, partially shaded, soggy shoes kinda places.   The scentless nectar-free flowers with males and females on separate plants are reportedly wind-pollinated.    Some plants have one big deal to feature, and others, like this, have a collection of little deals.

Little Deal #1.  The Red Admiral Butterfly is a rare treat in my experience, and requires members of the Nettle Family as larval hosts.   That is interesting, because nettles have tiny crystals called cystoliths embedded in their leaf tissues.   Nobody knows for sure why cystoliths exist, and there are multiple possibilities, but the most-obvious notion is to prevent insects from devouring leaves.   That being so, a caterpillar able to cope with cystoliths would have a monopoly on the foliage of the cystolith-defended plant.   Cystoliths are mostly calcium, as are kidneystones, which likewise are called cystoliths.  Botanist Bob Wise in Wisconsin is the world’s authority on cystoliths, in plants, not in the bladder.  He generously e-mailed this photo of Boehmeria cylindrica cystoliths:

Little Deal #2.  Another name for today’s species is Bog-Hemp.  Hemp? Boehmeria has long strong fibers valued by Indigenous People long ago for cord, nets, and bowstrings, and valued a little it seems by modern hobbyist weavers who favor natural products.    No huge surprise, really, because the commercial Ramie cultivated for thousands of years for its strong pliable fibers is Boehmeria nivea.    It looks much like its American cousin but with the leaves white beneath. They used to grow it commercially in Florida pre-nylon, and a few diehard survivors still grow untended around the state.  And it’s not just fibers.  Anybody like glutinous rice cakes?  In Asia, a sticky gel from Ramie, a byproduct of the fiber industry,  helps glue the glutinous rice.   Using the gel as a substitute for the agar gel to culture bacteria in labs has been suggested.

Little Deal #3.  Generally, I regard the vast literature on bioactive plant chemicals as a mostly boring haystack hiding a few exciting needles.   Boehmeria cylindrica might (might) be one of those needles.  It yields an alkaloid called cryptopleurine, which has been popping up as medicinally interesting since at least the 70s. 

Given the present need for antivirals, let’s give cryptopleurine a fast nod.   Here is why it keeps generating journal articles.  In a general sense, the alkaloid is “cytotoxic,” that is, it kills cells or prevents their growth and division.  Harnessed, separated from side-effects,  and targeted, as if that is easy(!), such compounds are potential weapons against bacteria, cancers, parasites, and viruses.   Not that it has crossed the line to superhero status, but other plant alkaloids have, and well, you never know.

(A responsive supply chain)

Hamelia patens*

Rubiaceae

In and near our backyard butterfly garden there are about six firebushes, three of them planted by me in convenient places, and three by birds in weird places.   Birds devour the fruits, produced year-round although in uneven quantities. Hey, being a member of the Coffee Family, maybe they have caffeine. (Just kidding, I think.)

Anyhow, the red and black juxtaposition among the variably aged fruits is one often seen in fruits and seeds of other species that attract birds.   (Think of Precatory Beans, or Nutmeg, or Coal Bean seeds, or ripening blackberries.)

And there is more to the color variation than just advertising.  What’s the point of advertising if you can’t meet demand? The sequence of Firebush fruit ripening is green to cream to pink to murder-scene blood to black.   As UF ecologist Douglas Levey documented in the 80s followed up by others,  when birds (or experimenters) remove the ripe fruits,  the Firebush promptly ripens new ones.  Sort of like when shoppers remove the toilet paper from the shelf in Walmart, the store brings out more (we hope).   No big surprise in the box store,  but a pretty neat supply chain trick for shrubbery. And, in addition to feeding the useful bird seed dispersers, the replenishment of black fruits continues the red-black advertising.

You might wonder, as researchers have, if the responsive ripening is merely that removing older fruits frees up sugar to beef up younger fruits.   That does not seem likely because extra sugar would probably go into the smallest green fruits, but the opposite happens.  When migrating birds gobble up the ripe fruits the plant needs more ripe ones immediately while the migrating birds are still around.  So the accelerated ripening tops off the almost-ripe fruits.   In other words, the nearly ripe fruits are safely in reserve until hungry birds send the signal, “hey, get ripe, we’re here and hungry, it’s crunch time.”

*Not relevant, but to cover all bases I should mention that botanist Thomas Elias,  who studied Hamelia in depth a few decades  ago, pointed out the  that a variety of Firebush (var. glabra) in the nursery trade is not native to Florida, whereas a different variety of the same species (var. patens) is.  Click for a summary.   

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