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About George Rogers

Florida botanist

Smart Dollarweeds Walk Away from Trouble When They Can

24 Apr

Hydrocotyle varied species (Dollarweeds)

Apiaceae (Carrot Family)

Marsh plants are fascinating because their sprawling patches can be single clones, one big individual all laced together by rhizomes,  one gigantic plant, and that breeds interesting questions, such as when patches collide…is it individual plant vs. individual plant,  planto-a-planto? (Not for today.)  When a patch of Dollarweed, and this is not hypothetical, differs genetically from a different patch of Dollarweed when the two are in different places with different conditions, what is the basis for that genetic difference? Quick localized genetic adaptation, instant evolution,  causing differentiation of originally identical starts? Or did two genetically different seeds each wind up thriving where their own unique genetic palette was optimal?  Or neither?   (Not for today.)  What is for today is botanical braniac behavior by  Dollarweed, a prospect raised most saliently by ecologists J. Evans and M. Cain in 1995.

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Today’s photos by John Bradford.

A clonal patch resembles a giant amoeba…it can expand this way and that depending on circumstances;  some portions stumble into bad areas and fizzle, while other portions expand into favorable zones and thrive, branch, and expand.   Nothing amazing there.   Anyone who has faced  tree roots in a sewer pipe  may now bow to the Roto-Rooter  Representative.

Now back to amoeba business.  A slime mold is much like an amoeba as big as your hand.    The “plants have intelligence” enthusiasts tout the mold’s ability to “solve” a maze with food at the end.  SLITHER HERE  Well sorta…it slithers hither and thither and then dies out wherever there is no food, thus producing ultimately one surviving strand leading to the oatmeal…biologically amazing and complex, but not “solving” the maze like a slimy little Hercule Poirot.

Hydrcotyle has its own smart trick.  Remember the concern above about expanding wastefully into unfavorable places?   Wouldn’t it be nice to avoid evil before stepping into it?   Yes!  A clone of Hydrocotyle can steer its rhizome growth clear of competing grass clumps.   A skeptic might ask, “is it merely that the grass roots block the Hydrocotyle rhizome?”  Naw, they checked on that.   The rhizome veers off safely before contact like I alter course (usually) before blundering into a stinky crocodile-infested malarial miasma on my explorer map.

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Now we all agree prescient side-stepping is  fancy for a lawn weed.  Complex and responsive yes,  but “woo-woo OMG! don’t hurt the sentient plants,” no.  Although the behavior is not explained, it is easy to suggest mundane ways the Dollarweed avoids trouble.  Evans and Cain suggested perhaps it senses the area of nutrient-depletion surrounding the grass roots, or maybe root secretions are the no trespassing signs.  Experimenters will nail it down if that has not occurred already.  What makes me more curious is, what additional marshland green amoebas have radar,  or engage in other cool behaviors?

 
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Posted by on April 24, 2020 in Hydrcotyle, Uncategorized

 

Gratiola – Herb of Grace

17 Apr

Gratiola ramosa

(Gratiola means “petite gratifying” (flower), and ramosa means branchy.)

Plantaginaceae

Verboden masthead

Masthead on Dr. Garleanne’s Gratiola article.

Some species are a little mysterious.   Gratiola is a lovely wetland wildflower you have to stop and bend over to enjoy.   Like Rodney Dangerfield, it gets no respect, and no botanical attention. The literature on these plants is a black hole.    Gratiola resembles a set of additional short-statured more or less related wetland species easily confused with each other:  Axil-Flower (Mecardonia), (False-Pimpernels, species of Lindernia), and Bacopa species, sometimes also called “herbs of grace). They can be mildly confusing to sort out…not the time and place.   With Covid dominating everything, it is tough to get out and botanize.   Almost all natural areas are closed.   Near my home is a small unnamed unofficial wetland I’ve been haunting socially distanced, befriending Gratiola.

GRATIOLA RAMOSA 1

Gratiola ramosa by John Bradford. Petals whote, and yellow with stripes in the tube.

The only meaty account of Gratiola I can find is fun to read, although in Dutch.  I read Dutch fluently (thanks to Google Translator).   Speaking of botany under duress, the account was written in the Netherlands in 1947, based on explorations in 1946.  The Netherlands in 1946? Wow.  And it makes me feel good that back then somebody,  Dr. A. J. M. Garjeanne, went out and enjoyed Gratiola too.  We had a parallel experience some 70 years and an ocean apart, and we noticed some of the same things.

gRATIOLA RAMOSA BUD

The bud by JB.

  1. Dr. Garjeanne asserts: “Even in the still closed flower, the dust is already spreading out.”

The dust is the pollen…in short, the flowers release pollen before they open. That could indicate self-pollination, or merely that the flowers function as “male” before turning female.  That Dr. Garjeanne had trouble finding immature and mature fruits put the kybosh on self-pollination, so he preferred the latter interpretation of male-first.   In our area Gratiola makes fruits.

  1. In the words of Dr. G: “I can assure you that the stigmas on my specimens  …  are not irritable. In the few hundred flowers that I looked at, the stigmas were always on top of each other, and touch with a pencil, a needle and a pen did not change that. The stigmas  do separate from each other by gentle lateral pressure (as is done by children with snapdragons).”

This requires some explanation and is interesting.   In our local species the style and stigma (the pollen-receptive organ) looks like a garden hoe, the handle of the hoe being the style and the blade of the hoe being the stigma.  Dr. Garjeanne perceived the hoe blade to be two flaps pressed tightly together, like two pages in a book.  His illustration is below.   I have tried to separate them under a microscope and fail.  Also like Dr. G., I have poked and prodded them to find no irritability (motion in response to physical contact).

style and stigma Dr. G

Dr. G’s picture of the large basal ovary, and the style and stigma toward the top. See the hoe?

 

Stigma Dr. G

Dr. Garjeanne’s 1947 picture of the stigma. He drew it with two flaps.

Gratiola style

Hoe-shaped style and stigma yesterday. I cannot discern two flaps.

  1. To quote Dr. G: “We have already said that insect visits to Gratiola are so infrequent that I have not observed any visits, although in two cases I have found thrips in a flower (one in each flower).”

Me too.  I have watched eagerly for the bees presumed to pollinate Gratiola and find it hard to catch pollinators in the act…but have caught on a GoPro footage of a small hymenopteran visiting two flowers and diving in fully fr a several seconds.

CLICK

I’m sure they visit, but to agree with Dr G., not during my peeping, and guess what, I too find thrips in the blossoms.   Thrips pollinate some flowers, but I kinda doubt they are important pollinators in Gratiola. Leave that to the bees lured by lots of nectar even if not when  Dr. G or I watch. Thrips eat pollen, and I wonder if the complex structure of the Gratiola flowers protects pollen from thrips, as well as from other thieves.

Gratiola thrips

Yep—thrips

If you look into the mouth of the flower you see a tangle of hairs you might say on the “roof,” with the flat face of that hoe-shaped stigma blocking the tunnel.  The handle of the “hoe” extends back into the flower along the “roof,” and the blade partially blocks passage deep where the treasured nectar and pollen hide.    The  two anthers resides just interior to the hoe-blade style…the blade effectively shields the pollen, which seems also to hide behind the mass of hairs on the roof of the tube.

Gratiola downthroat3

Lookin down the throat…there’s that big flat stigma blocking the tunnel.

 

There is a second purpose for the mass of hair according to other observers. Those sneaky private bees allegedly use the hairs as a foothold as they push deeply into the flower tube.  Doing that would rub their bellies across the pollen-depositing anthers as well as against that weird hoe-blade pollen-receiving stigma.

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Gratiola stamens in fuzz1

Open flower. Stigma at the center with two anthers just behind (to the left).

 
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Posted by on April 17, 2020 in Gratiola, Uncategorized

 

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Does the Moss Really Grow on the North Side of the Tree?

10 Apr

(Does the lichen grow on the north side of the lamp post?)

Today’s blog is the result of John’s sharp eye and healthy exercise.  Riding his bike socially distanced around his neighborhood, he noticed something striking:   that multiple species of  lichens on the lamp posts are 100% confined to the north edge of the post.

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North is on the left. Photos by John Bradford.

By contrast, when you look at the “moss” growing on a tree trunk…real moss, algae, lichens, liverworts, fern gametophytes…all the growth is scattered around the trunk irregularly and in response to such variables as sun and shade,  water flow patterns, lawn sprinklers,  bark texture, nooks and crannies in the tree, competitors, and who knows what else.   It is fun to try to figure these things out.   You often find lichens on the brighter exposed sunnier ridges, algae and mosses lower and shadier, and liverworts in “waterfalls” where branch crotches funnel water running down the trunk.

red lichen

Lichens on a bald cypress, by JB.

But John’s experience resembles a well designed experiment with variables suppressed, a uniform surface, and under that circumstance, the lichens show their true predilection…north side, period.

Examining the poles in the “heat of the day” we noticed the sun lighting up the south, east, and west sides, leaving  a shaded vertical stripe inhabited by lichens of the north face. Like me under my beach umbrella. A quick look at a website showing shadow patterns year-round showed…during the hot hours…the north to be shaded all year.   Landscape architects know this.   We used to do a lesson in landscape design class showing that some points in the yard virtually never experience direct sun during the bright hours.

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The poles are black fiberglass (or have fiberglass sheath covering something deeper within). How different were the two sides of the poles on a sunny afternoon with the air temperature 78 degrees F?   We checked several poles, on the sunny sides in degrees F: 115, 113, 113, in contrast with the  lichen-zones: 91, 93, 89.

Just for interest, we checked a palm trunk in the sun. The south side was an arctic 93, and the north side was 86,  which might help explain lichens surrounding the palm in contrast with the light posts.

The absolute absence of life on the poles with surfaces exceeding 100 degrees as opposed to plenty of lichens with temperatures in the 90s agrees with a broad general perception that at about 95 degrees life becomes supremely stressful in terms of cell membrane dysfunctions and protein denaturation (damage).   With obvious highly adapted specialized exceptions… cacti in Death Valley, bacteria in hot springs,…sustained unmitigated temperatures over 100 could be predicted to filter out most life,  even tough lichens.

 
9 Comments

Posted by on April 10, 2020 in Uncategorized

 

Local Ferns

10 Apr

Note from George Rogers…a chart of local ferns by PBSC student Sydney Kenney….

 

ferns Sydney Kenney

 
3 Comments

Posted by on April 10, 2020 in Uncategorized

 

Native Tillandsias by Sydney Kenney

05 Apr

Note from G. Rogers:   Putting Covid days to good use…I like this creative chart by PBSC student Sydney Kenney.

 

Native Airplants

 
7 Comments

Posted by on April 5, 2020 in Uncategorized

 

Using Natives in the Landscape

04 Apr

By Jayme Rieuf

Note from G. Rogers:  This essay is by horticulture student Jayme Rieuf, written during the Corona downtime.   This is so true, and so well written, I felt moved to share it on the blog. Thank you JR.
Using native plants could arguably be the most valuable thing one can do for their landscape for many reasons. Native plants are classified as a species that occurs naturally and thrives in an area in which it originally evolved. Native plants in any given area, state or every country differ. To begin native species are in fact better conditioned to the local environmental conditions. An example of this would be Forestiera segregata also known as Florida Privet that has adapted to sustain in Florida’s hot sandy soils. Native plants on average use less water because they are established to conditions of the area. This saves water which is considered a very valuable resource.
Species that are grown in their native environment usually are not in need of as much assistance from crutches like fertilizer, pesticides or even excessive watering patterns. In convential landscaping most often pesticides are over used or wrongly applied, which can actually kill beneficial insects which may be doing good for your plants. Not to mention how terrible pesticides can be for the environment and the one handling the product. With native species the minimization of these products means less runoff into oceans, streams and even our drinking water, which improves water quality for humans and animals. But this also reduces risk to humans for the long term with less handling, inhaling etc. of such toxic products.
Maintenance is lower in Native vs. Conventional landscaping because mowing, trimming etc. is not needed as frequently, which helps reduce use of non-renewable resources but also protects our water and air quality. As the world evolves the importance of air quality is increasing. Air quality is protected with reduced emissions of air pollutants caused by things like the gasoline from mowers, leaf blowers etc. Natives definitely reduce maintenance. Landscaping with natives is a positive for the environment by making an area healthier and introducing diversity of seed spreaders and pollinators alike. Luring in different species of birds, butterflies and other insects and animals adds to the beauty of one’s property and helps out others. This also proves to be an opportunity to educate our neighbors or friends on ways they can improve their own landscape saving time and energy. That may even encourage some balance of landscape designs to add a touch of coordination between properties.
The most valuable reason for using native species in your landscaping is the fact that it saves you money, because they practically take care of themselves. Native species evolve for survival over many years. They have adapted and will continue to adapt to our ever-changing conditions. Native species are valuable to landscaping for a number of reasons, if people understood more about the advantages of going for a native landscape they may be more opt to do so. That is the beauty of choice however, some people are high maintenance like their lawns. Taking this natives class has honestly given me such an appreciation for the species that are actually “meant to be here”.
Coreopsis gladiata 3

photo by John Bradford

 
4 Comments

Posted by on April 4, 2020 in Uncategorized

 

Brookweed

03 Apr

Samolus ebracteatus

(Samolus comes from an ancient name for a related species.    Ebracteatus means there are no small leaves mixed with the flowers.)

Samolaceae

There’s a special “breed” of wildflower that I love to see and ponder…species that start their lives in water and then wind up high and dry as the season dried out, often very dry…from one extreme to the other.  Such wet-to-dry types always have interesting tricks up their sleeves.  “Brookweed” is a semi-misnomer for today’s species.   Yes, you can find it in brooks, but you can also find it in dry deserts where water had accumulated previously, in salt marshes, and, in Palm Beach County, on dry sand baking in the sun.   It favors alkaline conditions.   Today you’d never know it has anything to do with “brooks.”

Samolus ebracteatus in dappled sun

The leafy rosette at the base looks like something straight out of Arizona, with thick, succulent, waxy-looking  leaves  in a twisty rosette with some red sunscreen.  The rosettes of most plants have leaves that lie flat against the ground—think of a thistle or a dandelion.  But the brookweed rosette has the leaves contorted so that they tend to face the sun edge-on rather than the more normal face-on, the contorted  configuration cutting down on direct solar radiation at mid day, and at the same time maximizing wind exposure, allowing cooling.

samolus ebracteatus on cam ranger

The white flowers are about ¼ inch in diameter on short stalks arrayed along a long wand.  They mature from the base upward as the wand grows, so as the season progresses the plant keeps making new flowers over a long time period while lower down fruits mature from the older flowers and release seeds. The entire reproductive cycle occurs all at once.

Seen from the side,  the flower looks like a tiny vase.  The upper rim of the vase is lined on the inside with five pollen-producing anthers mixed with fuzz.   The pollen-receptive style rises straight up from the vase floor. As the style rises it passes through the ring of fuzz and anthers which cover the tip of the style (the stigma) with pollen. That pollen germinates and completes the sexual cycle, all contained within the same flower.  No need for the birds and the bees.

samolus above green1

Style and stigma with self-pollen germinating.

That last statement is maybe a little over-stated.  Despite the self-pollination, bees and butterflies do visit the flowers.  Perhaps they bring a little outside pollen just to shuffle the genetic deck a bit.

There’s one more weird thing.   On the outside of the flower at the base, there is a donut of glistening wet material around the “bottom of the vase” surrounding the point where the flower stalk is attached.   A mystery.  Can’t imagine the shimmering gel attracts or feeds pollinators who could not get at it down and outside.    I suspect it is “flypaper” to prevent little crawling insects from bothering the blossom.

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Sticky ring around the base of the flower

 
3 Comments

Posted by on April 3, 2020 in Samolus, Uncategorized

 

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Bladderworts High and Dry Where Bladders Don’t Belong

27 Mar

Utricularia cornuta

(A utricle is a bladder. Cornuta means horned, referring to the spur on the flower.)

Lentibulariaceae

ut corn 2

Horned Bladderwort by John Bradford.

Many wildflower enthusiasts are familiar with Bladderworts, species of Utricularia.    Utricularias are generally thought of as aquatic carnivorous plants dangling microscopic suction traps in the water.  The traps have trigger hairs and a trap door. When a minute swimming arthropod bumps the trigger, the trap sucks the victim in for lunch. That is documented richly on the Internet so no need for more here.

What has been interesting me this week is Utricularia growing in moist sand, often by the thousands in drifts of yellow.    Any questions? Question 1:  What pollinates a hundred thousand bright yellow blossoms all glorious at once in a couple acres?  That’s a blog for another day.

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Question two is the topic for today:  How can an aquatic water-filled bladder catch water-borne prey while stuck in sand?  There has to be more to the story. There is, some of it well known, some mysterious.   As the pundits say, “let’s unpack it.”

First of all, don’t the plants root in the sand? No—Utricularia has no roots, although we will soon see leaf-ish structures functioning much like roots.

But let’s stay above ground a moment.   Plants typically need to photosynthesize, and that is a job for leaves.  But where are the photosynthetic leaves?  The plants look like a bare stalk with a flower out of focus on top.

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utricularia cornuta snorkel stems 1

Vertical pins rise from the leafy mesh below the surface.

Just below the soil surface stringy leafy segments form a horizontal mesh, think of a smashed plate of spaghetti.  From that mesh millions of pin-sized segments rise vertically from the soil into the light of day.  The collective surface area of countless pins is substantial, like the microvilli in an intestine. They are green or partly red (sunscreen? damage?) and probably allow for photosynthesis, and conceivably help aerate the leafy portions below the surface, especially during flooding.    Room for research here!

A growing literature is revealing the idea of the trap feeding the plant by catching and digesting prey as simplistic.   The traps seem to be micro-ecosystems unto themselves.  CLICK

Trap-dwellers include microscopic protists, such as ciliates, bacteria, fungi, algae, and so-called bluegreen “algae.” Bluegreen “algae” are photosynthetic cyanobacteria often able to “fix nitrogen,” that is, convert atmospheric nitrogen to fertilizer.

The microbes manufacture nitrogen fertilizer inside the trap, you say?   Isn’t the main point of the carnivorous plant to obtain nitrogen from breaking down the insect victims? And photosynthetic bacteria inside the trap provide the same benefit without bloodshed?   Yes, if not studied adequately yet.

OK then, nitrogen-fixing cyanobacteria live inside the trap, possibly contributing to the plant’s nitrogen nutrition, what about outside the trap?   Not a new idea.  Botanists have recorded cyanobacteria clinging to the outsides of traps in the water.

So now think about that comparatively dry meadow of sand-dwelling utricularias.   Could  cyanobacteria in the sand be enriching the soil, maybe replacing the need for aquatic bug-catchery?

A close look at a population of Utricularia on “dry” land shows them mostly to rise from a thin surface carpet of periphyton, although not always, and there’s more to the picture.  Under the Utricularia is a blue-green living layer a fraction of an inch under the ground surface.   It looks like a miniature seam of coal.

utricularia gtreen band

A living blue-green seam in the soil

With room for more data (!), I suspect the land-living Utricularia is deriving nitrogen and possibly additional nutrition from the subsurface blue-green layer.  A look at that layer with a microscope shows it to consist in large part of, you guessed it, cyanobacteria.

utricularia cysnobacteria3crop

Cyanobacteria from the blue-green layer at the base of a Utricularia.

The plants form a thick brushlike mass  of rootlike leaves usually just below the green layer, or sometimes branching directly into it too.   The false roots can have traps, which exist to absorb nitrogen.   But who said it has to come from within?  Traps bathed in nitrogen fixed by a living soil layer of Cyanobacteria might as well absorb it from the outside as well.

 

 
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Posted by on March 27, 2020 in Uncategorized, Utricularia cornuta

 

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Sweet Shaggytufts

22 Mar

Stenandrium dulce

(Stenandrium means narrow anthers.  Dulce means sweet, probably in reference to the flowers although I detected no fragrance today.)

Acanthaceae, the Acanthus Family

For a variety of reasons I’ve let the blog lapse in recent months.  But here we are with isolation time for  nature.  So today I took to the Covid-free swamps to re-find a large population of Sphagnum to help with a friend’s research effort.   Plans take odd turns.   Out of the shrubbery scampered a big mother feral hog with cute baby(ies) and stood her ground in the path making grumpy snorty sounds, so I headed in a different direction, passing Sweet Shaggytufts during my craven retreat.   Now that’s a pretty species you don’t see every day, or every decade.

Stenandrium plant

We live near its northern limit, in Georgia, from which the plant extends southward to Chile.   Ask three observers what the natural habitat is,  and you will get three different answers.  It is one of the several species occurring locally that live like toads…starting out in water and ending up high and dry, often very dry.  Despite being semi-“aquatic” Stenandrium turns up on hot sun-baked sand, such as it did today, even in deserts and similar circumstances.  It spans both extremes, which is not unusual in South Florida.  Additional amphibians coming to mind include Brookweed (Samolus ebracteatus),  Hornwort (Mitreola petiolata), Small Butterwort (Pinguicula pumila),  and Oakleaf Fleabane (Erigeron quercifolius).

Stenandrium forms rosettes flat on the ground, often lots of rosettes, apparently from self-seeding.   It likes open space with no competitors and reportedly can  maintain its social distance by making natural herbicides.

stenadrium flower oblique

Today’s flower is a member of the large family Acanthaceae where the vast majority of species have microscopic pointy crystal-like structures in their leaves, called cystoliths.   Nobody knows what cystoliths are good for, although discouraging herbivores is a distinct possibility.  Stenandrium is in the small branch of the family without cystoliths, and (to speculate shamelessly) I wonder if the absence of cystoliths allows it to host the Definite Checkerspot Butterfly larva.  Perhaps the missing cystoliths force the  need for protection using the insect-feeding deterrent called benzoxazine. (Many caterpillars have the ability to tolerate and sequester toxins from the host plant.)  Don’t eat the weeds.

Even in 2020 what pollinates those pretty pink flowers is unknown.    Birds, wasps. and bees do not fit.  Moths are possible.  Butterflies seem most likely, and it would be fun to sit in the Shaggytuft patch awhile and see what flutters along.  I might just try that…although waiting for pollinators requires more patience than fishing.  Neither fish nor butterflies care about your timeframe.

 
14 Comments

Posted by on March 22, 2020 in Stenandrium, Uncategorized

 

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Wild Coffee and Friends—Tropical Species Coping in Florida

20 Dec

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.

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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.

stipules opened with gradient

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.

Psychotria old stipule

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.

Psychotria white colleters

Fresh colleters at stem tip during secretory phase.

Psychotria cut tip

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.

Ficus bud

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.

Seagrape bud

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.

Annona bud

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.

 
4 Comments

Posted by on December 20, 2019 in Uncategorized, Wild Coffee Stem Tip

 
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