Wild Coffee and Friends—Tropical Species Coping in Florida

Psychotria nervosa

(Psycho refers to a person’s health and spirit, reflecting medicinal perceptions for some members of the genus. Nervosa refers to the sunken curved leaf veins.)

Rubiaceae, The Coffee Family

 

Wild Coffee is an abundant native shrub popular in landscaping. So pretty!   To dispose quickly of an old question, no, it is not coffee that is wild.   The connection of Wild Coffee to Dunkin’ Donuts is merely a superficial resemblance to a true coffee plant and membership among several thousand other species in the vast Coffee Family, along with Ixora, Pentas, Mexican “Clover,” Snowberry, Firebush, and many additional familiar plants.    The genus Psychotria itself has over 1500 species,  and includes a prime ingredient in hallucinogenic ayahuasca.   This has nothing to do with our Florida shrub which gives no high, is not edible, and can reasonably be presumed to be toxic.  Wild Coffee is a terrific example of a mechanism to promote cross pollination called heterostyly described several years ago in this blog.  CLICK

After a hiatus of some 8 years, here  now is a different oddity of Wild Coffee, one repeated among the Rubiaceae.    A little context will help:

Stipules  are outgrowths in some plants where the leaves join the stem.

The Coffee Family has a peculiar sort of stipules, called interpetiolar stipules, which are flaps connecting the bases of the paired leaves.  Each leaf pair has on both sides of the stem a pointed or rounded (or fringed) stipule rising up and pressed against the stem.

At the tip of the stem two stipules cover the growing tip.  Think of two hands clasped in prayer with an egg (the growing tip) between them.

Now the interesting part.   On the base of the inner face of each stipule is a row of finger-shaped organs called colleters (CALL-eh-ters).   You can see older brown or black colleters between leaf bases along the stem where aging stipules have dropped off.

Old stipule falling off. Colleters from its inter face visible as brown hairs between the leaf bases.

In the stem tip, by contrast, the colleters are fresh, white, and secreting a sticky fluid the color and consistency of Elmer’s Glue which fills the chamber between the stipules.

Fresh colleters at stem tip during secretory phase.

Wild Coffee stem tip sliced open.  Note the white fluid mixed with the immature leaves.

Botanists have speculated on the function of the fluid. Given that it surrounds the tender growing tip, the standard interpretation is it protects the tip.  Okay, but personally I think that’s not the whole truth.   As the stipules part and young leaves come forth the young leaf blades are wrinkled and sticky with the white fluid.   Seems to me that the crinkling delays direct sun or wind exposure on the emerging leaves, and that the persistent fluid may add protection from drying until the leaves mature a bit.

Time to broaden the perspective.  Wild Coffee is a tropical species with a northern extension, growing from  hot South America to frosty Duval County (Jacksonville area).   Interesting that a tropical species with a toe into the nasty “north” has a well protected growing tip.  Plants that evolved in cold climates generally have bud tips encased safely under tiny bud scales to get through the winter.    A tropical plant penetrating into harsher climates has to have “its own” protection.

Now don’t get me wrong, I’m not suggesting that the plant developed the fluid-filled stipules in response to its high-latitude expansion.   Fact is, many tropical plants have various devices to protect their tips from sun, drying, insects, wind, infections, and more.   Perhaps some of those protective mechanisms help certain tropicals expand into climates harsher than where they originated.  Like cool counties in Florida.    Tropical plants extended into Florida face tough conditions beyond cold.   Without a statistical study, I think it safe to say that most of our tropical species live near the warmer yet windier and saltier coasts.   And in addition to chilly temperatures we have plenty of blazing heat, dry times, fungi, bugs, wind, and tough livin’.

Let’s look at some additional tropical species with northern limits in Florida and see about their bud protection:

Strangler Fig, Ficus aurea, grows from Central America to Volusia County (Daytona).  Its growing tip hides under a thick nose cone formed by the stipule on the topmost leaf.

Strangler fig nose cone (stipule) at stem top covering bud.

Red Mangrove, Rhizophora mangle, growing all around the tropical world and extending north to the Florida Panhandle (and rarely farther), likewise has a giant slime-filled nose cone over its bud.

Seagrape, Coccoloba uvifera, is a third species with a bud tip nose cone.   It reaches from South America to Flagler County (a little south of St. Augustine). (For those familiar with botanical terminology, the cone is the ocrea.) The cone is filled with a clear gel that might add protection in the bud phase or perhaps by “varnishing” the baby leaf as it grows forth.

Sea Grape nose cone over tip bud, sliced to reveal gel.   Object rising on the right is a leaf base.

Pond Apple, Annona glabra, extending north to Brevard County from South America, has its tender tip hidden beneath the base of the topmost leaf until new growth pushes off the protective older leaf.

Pond Apple. Leaf stalk (green) completely covers stem growing tip.

We could go on, but that will get boring, especially because the point here is that this is something fun to explore, not to list.

 

Jack in the Bush Goes (Almost) Pollen-less

Chromolaena  odorata

Asteraceae

 

Across vast areas around the warm-climate world, including Florida, lives Jack in the Bush, a huge, raggedy, hairy, smelly,  weak-stemmed weed up to 10 feet tall, often leaning on other plants.   The leaves often look bedraggled, and they suffer often from leaf miners.

The flower heads start out white and wind up borderline pretty and pinkish, fuzzy, with long protruding stigmas.   They attract several species of butterflies as well as additional insects.  Notice I did not say insect “pollinators,” because the bug visits are pointless to the flower…there is almost no pollen.

Jack in the Bush, white phase. Both photos today by John Bradford.

Members of the Aster Family generally share a common basic pollination plan.   The flowers have 5 male pollen-making anthers joined edge-to-edge into a tube with pollen released into the hollow inside of the tube.  The female style then rises up through that tube and either pushes pollen out like a plunger ahead of its  two pollen-receptive stigmas, or the style drags pollen out of the tube using a “bottle brush” below the stigmas.  Jack belong to the bottlebrush type.    Its long style rises dramatically from the anther tube exposing two big long stigmas just asking to be pollinated.  Below the stigmas on the style is the bottle-brush where there ought to be pollen.   Only problem is, there’s almost none.  What’s up with that?

Mature flowers. The long threads are stigmas on the styles.

Knowing a plant to be a worldwide weed is a red flag to look for some ability to reproduce rampantly without benefit of separate individuals of the same species.   That is, for a pioneer to be able to make seeds all alone. There are many such mechanisms, and one is to make eggs that do not require sperm, or in more botanical terms, viable seeds bypassing pollination.

True of today’s species.  Jack in the Bush has six sets of chromosomes instead of the usual paired chromosomes we think of as normal.  Extra chromosome sets are not rare in plants, and have different consequences in different species.   Normal paired chromosomes matter during formation of eggs and sperms.    Our chromosomally abnormal weed cannot make pollen, at least not much of it.   So how does it spread like a weed?   No problem,  the extra chromosome sets do not prevent egg formation,  In fact, just the opposite, eggs form needing no pollination.  The embryos are clones of the mother plant.

Probably all the Jack in the Bush in Florida is probably one big genetic clone.  The butterflies love it nonetheless.

 

Red Mangrove Embryos Bob Bob Bobbin’ Along

Rhizophora mangle

(Rhizophora means root bearing.  Mangle is Spanish for mangrove.)

Rhizophoraceae

Red Mangroves astound in many ways. One of the is the embryo.   The Red Mangrove embryo bobbing in the sea looks like a purposeful eel swimming vertically with its head above water.  Before getting far into the swimming, a few words on the embryo’s nuts and bolts.

A normal fruit on any other plant contains one or more seeds, and each seed in that normal plant houses a tiny embryo destined to grow into a new oak tree or orchid.    But Red Mangrove is not normal.   It makes a small rusty-leather fruit the size of a strawberry containing two seeds., one of them surviving.   So far so good, but now it gets weird.  The seed sprouts while the fruit still dangles from the parent tree.  The resulting embryo, resembling a large green bean, grows forth from and eventually dwarfs its fruit and may reach about a foot long and a half-inch in diameter dangling from the tree, the original fruit forming a brown cap around the green embryo’s attached upper end.

Embryos looking like green beans hanging on the parent tree.  The fruits are the brown caps at the upper ends of the embryos, which will soon drop free leaving the fruits behind on the tree.

 

When it finally comes time to go float to a new beach, the embryo breaks free, leaving its topmost parts (the cotyledons) behind within the fruit.   The part that falls into the sea then is an enormous root (hypocotyl) vertical below the water line with a little pointy tip exposed above the surface.  The pointy tip is the beginning of the top part of the future tree, the embryonic leaves, stems, and trunk.

Embryo floating in the Atlantic Ocean.

The pointy tippy top.

Why does the bottom end stay down while the top end stays up?    Not only is the bottom thicker, it also fails to have something the top possesses…open hollow airspaces.  The spaces clearly give the top end buoyancy, and perhaps have an additional role in gas storage and exchange.

Hollow spaces seen when the top part of the embryo is sliced open.

Here is the kicker.  The floating embryos cross oceans.   Their cruise can reportedly last a year.   For all those months the sojourners do not merely dormant and sleep their way across a thousand miles.  Rather, it looks like they live and breathe along the way.   Even when the root end down in the water turns brown, the upper end remains green and has chloroplasts.   There must be a reason the little swimmer keeps its head above water, no doubt the same reason I do…life support, gas exchange.   Those little submarines have circled the earth bobbing along with their  snorkel tops peeping above the waves.

 

Narrowleaf Yellowtops is a Pollen Pusher

Flaveria linearis (Flavus is Latin for yellow.)

Asteraceae

 

Must be October, the Yellowtops glow goldenrod autumn,  rich canary yellow in wet meadows and beyond.  They’re a friend to many pollinators.  Fact is, it is fun to get among the plants and see what visitors show up.

Photos by John Bradford

No need to linger on a boring point of physiology, but it is my duty to point out that this species is an intermediate in terms of C3-C4 photosynthesis.   The first, C3, is “normal” photosynthesis, typical of temperate plants.   The second, C-4 photosynthesis, is a biochemical and anatomical specialization typical of many tropical plants.   A plant has to be one way or the other, or does it?

Three native Flaveria species grace Florida:  Two are intermediate C3-C4. They are F. linearis and F. floridana which DNA shows to be a narrowly distributed Gulf Coast offshoot of the widespread F. linearis.  What’s interesting is that F. linearis ranges into cooler north Florida and into the hot tropics.  Is that the benefit of having mixed temperate-tropical photosynthesis?

Our third native species, F. trinervia, is not closely related to the other two.  It is C4 and evidently a South Florida visitor from a worldwide tropical distribution…with surprising (brief?) cool-climate extensions.

Members of the Aster Family often dish out pollen in more complex and intriguing ways than are conspicuous at first glance.  So it is for Narrowleaf Yellowtops. The flowers are reluctant to release pollen until an insect comes probing and stomping.  Bug-pokes cause the little blossom to push out pollen within seconds of contact.   Watch it happen in the brief video below where a fake insect provokes pollen expulsion.

Pollen-pushing video. Be patient, the action is episodic and subtle:  PUSH HERE

 

Redroot Roulette

Carolina Redroot, Lachnanthes caroliniana

(Lachnanthes means woolly flower.)

Haemodoraceae

Carolina Redroot is famous for its namesake red roots.   Been there, done that:  CLICK

This wetland bleeder hangs around where feral hogs snuffle the earth.   Correlation does not show cause, however.   Do the hogs seek out the redroot?  Do they spread it?   Or does the plant happen to grow in mudholes hogs fancy for other reasons? I don’t know. And for this moment, I don’t care, because what I wish to discuss are the unusual flowers, visited at least by bees, wasps, and butterflies.

The butterflies come for nectar, and perhaps the bees come mainly for pollen.  Somebody is going to have to sit a long time in a marsh with camera, binoculars, and bug net to tell the full story of Lachnanthes pollination.

What’s  weird about the flowers is that seen from the side the style with its pollen-receiving stigma is bent outside of the floral center, at about the same height as the pollen-releasing anthers.

Side view of woolly flowers. Anthers are dusty yellow. Stigma marked with blue line.

Flower from above. Three anthers yellow. Style green angled up and left.

Seen from above, the stigma juts out to the side about as far as the likewise bent anthers do.  Picture the flower as a clock face.  In the photo above the anthers are at 12, 5, and 7 o’clock releasing dusty yellow pollen.  The green style with pollen-catcher stigma at its tip is at 10 o’clock.      The stigma is in a spot where you’d reasonably expect an anther. Within an inflorescence, the bent stigmas point in every direction.

What’s up with that?  One answer, not original with me, is that the stigma is out of the way of all the sundry pollinators, but it seems there is more to it.  Given that the stigma occupies an “anther position,” an insect visitor is as likely to contact the stigma as any single anther.   Visitors approach the flowers oriented variably.   Spot on the insect pollen-dusted on a different flower will occasionally hit the stigma spot.  Twenty-five percent of the flower touches will be pollen drop-off, the other 75 percent will be pollen pick-up from the insect’s standpoint. This presumably accomplishes two things:

Accomplished thing 1. Accommodation of the diverse floral visitors.   All manner of bees, wasps, butterflies, and who knows what can play redroot-roulette, even perched on one flower  sipping nectar from another, or while feeding vertically as well as horizontally.

Accomplished thing 2. The roulette system may help promote cross-pollination. The incoming pollen is scattered on various insect body points from past visits to other flowers.  The different pollen-pickup points on the insect may carry pollen from multiple flowers.   The pollen deposited on a stigma is equally likely to have come from any of many flowers, all depending on where the roulette wheel stops.   A great system for mixing genes.

Redroot roulette.   The insect in the diagram picked up pollen on its right side and deposited that pollen on the next flower it visited.  Perhaps on its next stop it will drop off pollen from its left side, or from its chin.

Partial to redroot is the gray hairstreak butterfly. Today one was alternating between two plants, ignoring all others.  Most of its flower action is head down, for a reason.   The head is inconspicuous, while the fanny looks like a showy head, complete with orange coloration, false eyes, and best of all, fake antennae.

Head down on redroot. Fake antennae “up.”

An attacker is likely to go for the wrong end of the butterfly.  You might think a bird would gobble it up altogether, so what good is that fake head?  Entomologist Andrei Sourakov from the University of Florida found out.   The predators fooled are not big birds, but rather spiders.  They inject their venom into the wrong end of the butterfly.  Score one for the graystreak.

Sipping nectar

The rear end with false eyelashes.

BRIEF VIDEO  Watch the fake antennae wiggle: CLICK

THE END

 

 

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.

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.

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.

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.

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

 

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 19^th 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.

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.

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.

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.

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.

Long thin rhizomes running hither and thither.

They are hollow gas pipes.

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.

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?