Author Archives: George Rogers

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Ficus microcarpa

Moraceae

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Every South Florida resident knows Ficus microcarpa as the ‘Green Island’ Ficus that has become a preeminent hedge and space filler selections in local landscaping.   It is bugproof and idiotproof, which is why I have it in front of my house.    Asking nothing in return, it just stays flawless green, and grows. 

When not serving as a hedge, “natural” Ficus microcarpa can grow into a giant multitrunked “banyan.”   Or to pivot to the small extreme, it is a favorite tropical bonsai species.   I have a couple of those on the back patio.   Or… it can be “the other” strangler fig in our area, sprouting on a host tree, and dropping its roots to the ground, wrapping the host in a “strangler” embrace in the process.  Ficus microcarpa is an unwelcome invasive exotic in natural areas.  One big “mother tree” can spawn many smaller-scale strangulations in its vicinity. 

How do you distinguish between Ficus microcarpa and the native Strangler Fig, Ficus aurea? 

Easy.   Ficus microcarpa lives up to its name by having micro fruits, its little figs ¼” in diameter, vs. twice as big in F. aurea, which also has larger leaves, say, 1.5” wide or wider, vs. about an inch wide and 2.5 inches long, and thick.  

 Ficus microcarpa is so prone to thrips infestation that you can use the insect damage to help with identification, the thrips causing leaves to fold double and to deform with ugly spotting and crinkles.   Interestingly, however, ‘Green Island’ is generally free of thrips, and is also free of fruits.

All of that is context for the cool thing.  Here it is.  How many plants do you know to use two-step seed delivery?  One step for long distance, then the second step local.  Today’s fig has spread all over the tropical world, and it then manages to sub-deliver its seeds into the nooks and crannies of host trees, or into cracks in concrete I-95 overpasses.   Its two step delivery was figured out back in 1991  by ecologists Sandra Kauffman and collaborators.   Birds who eat the figs handle the long distance airmail responsibilities. Toucans like them.  Then ants take over like creepy little mail carriers.  The seeds pass through the birds’ digestive systems with a layer of nutritive “ant food” intact ready to pay for ant services.   That layer is thin and hard to see, although the photo below captures it as the clear outer layer by the line on the right side of the seed.

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Polygonella polygama

(Polygonella means “little Polygonum.”   Polygonum is a related genus and may mean “many knees,” referring to thick nodes on the stem. Or, accoridng to Flora North America, it may mean “many seeds.” Polygama means polygamous.)

Polygonaceae

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How do you observe Florida scrub when the dashboard thermometer says 94?   Fortunately for me, my wife Donna has happy weekly business in Boynton Beach on Thursday afternoons.  So I tag along, then while waiting, sneak off in the car to visit the great scrub sites down that way.  I use the car as an air conditioned observation post while seeing the botany adjacent to the scrub parking areas, followed by an iced coffee from a convenient Dunkin Donuts..   You can spot a lot from a parking lot.  This week’s destination was the Rosemary Scrub Natural Area, with I-95 along its west border. A little gem with a ton of biodiversity.

Two species are in full beautiful bloom all over the scrub: Eastern Mikpea (last week’s feature) and October-Flower here and now.   The October Flowers are covered with snow-white flowers on the sun-baked sand.  The thousands of blossoms, with males and females on separate plants,  turn pinkish-violet with age. Females mature into a small triangular fruit resembling buckwheat, no surprise give the family relationship.   The species is at home in harsh Florida scrub habitats and has “satellite” populations from Texas to the Carolinas.

To get to the cool insects,  October Flower was a hotbed of activity.   Its buggy visitors were diverse. Plenty of bees visit this species, and there is even one, Perdita polygonellae, that specializes on Polygonella.   Nonetheless, at Rosemary Scrub on 8/26/2021 October Flowers was favored by wasps and a huge weird fly.

Today’s featured wasp certainly counts on bee visitorship.  Bee Wolf wasp (Philanthus sp.), well named, is a predator on bees.   The wasp lurks around flowery places and pounces on pollinating bees, stinging them into paralysis and carrying them back to the wasp’s tunnel-style burrow.   Worth mentioning, the wasp is armored against stings from the victimized bee.

A scary-looking visitor to the OF was the big-ol’ Mydas Fly shown below.  It is a harmless wasp mimic, as are many types of flies.  Nobody is going to mess with this gentle giant, which couldn’t harm a flea, although its larva would harm a beetle grub.  The larvae are subterranean predators regarded as beneficials in turf-growing situations.   The name Mydas is a tribute to King Midas, because Mydas Flies have gold markings.

Any bird watcher will tell us, “often it is best stay put and let nature come to you.”

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Megachile sp. (the bee)

Galactia volubilis (the pea)

Fabaceae—the legume family

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Today is movie day at the blog.  No worries, the movie only lasts a minute or two, literally. It shows the convergence of two wonderful species.

Eastern Milkpea is one of a trio of species so closely related they are tough to discriminate.  The present species is a climbing vine found across the southern U.S. and beyond.  It loves scrub habitats locally, and when spunky can cover old stumps, fallen trees, and living bushes.  

Pea-type flowers are complex.   I always wonder to what extent they are specialized for certain pollinators or for pollinator groups, if not single species.  Yes, it is possible to find diverse visitors to a pea-flower-type. Even so, there may have been a “key demographic,” just like I am sometimes a “visitor” at Bed, Bath and Beyond, but not the target demographic.  Fact is, I’ve seen wasps and “other” bees on Eastern Milkpea, but it sure gets along well with Leafcutter Bees. The fact that the bee opens the flower to access the pollen, and then the flower snaps shut as the bee departs is remarkable in itself, IMHO.

And why does a Leafcutter cut leaves?   Not for salad, but to line its nest in a hollow cavity.  Some folks who like them (I do) put out bundles of bamboo sticks, where the bees nest in the hollows.   They collect pollen by capturing it in the hairs on the underside of their abdomen, which consequently looks yellow on some individuals.  

There must be a reason the bee raises its fanny, bending it toward is head.   It took some internet searching, but aha! there is it is, in a 1964 Masters thesis by a very observant C. E. Osgood (relevant passage shown at end of blog).  When the abdomen is lifted and bet forward the hairs spread apart out straight to gather pollen like a comb from the legs, then when the abdomen is lowered, the hairs  push the pollen up against the abdomen and trap it. More or less.

A movie was promised.  Get the popcorn. Here is the plotline:

1. Leafcutter bee lands on Milkpea flower.
2. The bee uses its hind legs to gather and transfer pollen to the abdomen, which requires a lot of moving the abdomen around. The pollen is yellow.
3. Bee exists stage left.
4. There’s more….
5. Then look very very carefully and quickly:  at the center of the flower a tiny (I mean tiny!) black thrips (plant pest) pops out of the crease at the flower center for about a second, then ducks back into the groove. Why the furtivity?

Note: the cameo by the thrips is FAST. Don’t miss it.

1. A gigantic (relative to the thrips) ant appears and seems to look exactly where the thrips was.   Can’t prove it, but I think that ant is hunting for some thrips.

Enjoy the show and CLICK HERE!

Yes, thrips is a singular word. “I saw a thrips today.”

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Lined Treesnail  and Its Giant Spider Pal

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Florida scrub is home to even better creatures than the plants:  gopher tortoises, red widows, scrub jays, and so much more, not that scrub habitats are a joy to visit on a Florida summer afternoon.  It all started while looking for a way to put an hour to good use waiting for my wife’s business in the Boynton Beach City Hall.  I drifted to the nearby Seacrest Scrub, which led to a hot sweaty followup stopover in the Jupiter Inlet scrub today with tree snails on my mind. 

Guarding the trailhead this Tropical Orbweaver was the size of a small frog, encountered while searching for tree snails.   The spider spreads a wide web by night, and is a sleeping giant by day, cuddling up with its legs pressed together on the undersides of curled leaves.  It can “tuck itself in” with silk pajamas.  After this distraction, on to the tree snails.

Florida is home to a beautifully patterned tree snails with dozens of color variants in multiple genera.   They are more numerous around Miami and in the Keys where long ago they became a non-horticultural intersection between two early Miami horticultural Illinois-native transplanted titans, viz:

Titan 1.   William Krome (1876-1929) was the main construction engineer responsible for building the 128-mile overseas railroad out to the Florida Keys.    He also was an avid horticulturist, mainly interested fruit growing.   Krome’s homestead became a UF Research and Education Center where the breeding system of avocados was discovered.

Link to KROME

Titan 2.  Charles Torrey Simpson (1846-1932) was a  colorful, multifaceted, storied individual with several chapters in his life, a couple of them a little tainted.  Long story short, two points interest us today.  Simpson’s main career was a malacologist, a biologist who studies snails. His main (long) retirement second career was a rock star horticulturist/naturalist in the burgeoning Miami community.  Simpson was something of an environmental activist when it suited him, although he had no problem raiding natural areas to help himself to orchids and other native plants.

Fawning LINK to Simpson

Snail-hunting Simpson used Krome’s new railroad bridges and clearings for access to unexplored tree snail habitats, but at the same time, I believe, as an eyewitness, he disliked Krome’s destruction of the fragile Keys habitats.  (I cannot put my finger on it, but I think he criticized the RR habitat destruction in the Miami Herald. His general attitude on FL habitat destruction relative to the snails is mixed with description of walking the RR line in the Keys in the attachment at the end of the blog.)   Divine retribution for destroying even such modest works of Creation as snails was the 1935 Hurricane crumbling much of the overseas railroad into the sea.

Anyhow, it is fun and rare to spot a tree snail here and now, on a Hog-Plum (Ximenia americana) in the local scrub.   They are not hurting the tree, but rather consume algae and lichens from the bark.

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To dig in deeper:

CLICK for more

Taxodium distichum var. imbricarium (aka Taxodium ascendens)

Cupressaceae

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Pond Cypress has an inferiority complex…because its famous brother Bald Cypress (Taxodium distichum) gets all the fame. Different botanists classify Pond Cypress either as a separate species (Taxodium ascendens) or as a mere variety of the same species as Bald Cypress.   Nothing could bore me more than worrying about the semi-arbitrary eye-of-the-beholder question of “separate species or not?”  More a question of how you define a species than the soul of Pond Cypress.  Whatever designation you care to give it, the tree has its own style and grace.  Let’s start with what’s clearly visible.   Pond Cypress differs from Bald Cypress by:

• Having the needles arranged all around the twigs and bent upward up against the twigs, which tend to be upright. (In Bald Cypress the leaves are in just two rows projecting at right angles to the twigs.)
• Placing less emphasis on “knees” and more emphasis on swollen trunk bases.
• Tending toward smaller stature, with overlap

What is more interesting are their ecological differences.  If Pond Cypress is an evolutionary offshoot from Bald Cypress,  into what different niche did it diverge?

If you Google the two, you run quickly into assertions of Pond Cypress in more-acidic conditions.  Maybe so, but actual measured comparative data are lacking.  Although Pond Cypresses often occur on acidic sites, they also grow on alkaline substrates.  Around our area the two species occur as close as 50 feet apart with no likely difference in the soil and water pH.   My guess is that substrate pH is not at the center of the species divergence.

Seems to me a more incisive interpretation comes from reforestation projects associated with the massive Three Gorges Dam in China.  Researchers there studied the ecology of potentially useful wetland trees, including Bald Cypress and Pond Cypress, conducting physiological research on seedlings and young trees.  To paraphrase a long story, the main ecological distinction revealed in China is that Pond Cypress is more adept at mobilizing, processing, and redistributing nutrient resources in its roots, giving this species more environmental flexibility.   You might say Bald Cypress “wins” as specialist in its floody shaded narrowly specialized habitat, but step outside of that, and Pond Cypress deals more adroitly with diverse other habitats. 

Bald Cypress grown in bright sun keeps its flat two-rowed leaf arrangement with no adjustment. But Pond Cypress grown in shaded places adjust its leaves into positions similar to Bald Cypress, or if too sun-baked and dry, can shed leaves temporarily,  both abilities being examples of Pond Cypress’s ability to bob and weave.  The environmental flexibility is why Pond Cypress occupies different habitats in different parts of its range, is no doubt why it tolerates acid and alkaline situations, is why it fares better in cultivation, and why it is more drought tolerant.

Around Palm Beach County, you seldom see wild Bald Cypress outside of a Cypress swamp, be it along a river or in a large seasonally (or always) flooded depression swamp where the soil remains submerged or soggy.   Pond Cypress, by contrast, loves low slash pine savannas where the thin sandy soil dries periodically.  Its usual neighbors are pines, not Bald Cypresses.  Protection from drought and sun readily explain the clenched upright leaf arrangement.   That arrangement may slow growth, but trees are patient, and some Pond Cypresses are far older than their relative small sizes suggest.   

Occupying sunny open habitats, and upright twigs with upright needles makes for brightly illuminated branches, just what epiphytic bromeliads need.   Many Pond Cypresses are home to large numbers of airplants, but most are small, as though something keeps them in check.   Botanists David Benzing and Antoinette Renfrow back in the 70s found the constraint: Pond Cypress dwarfed by growth on especially poor soils turned out to have likewise dwarfed epiphytes.   The tree starves its hitchhikers by having low nutrient levels in the stemflow along it bark.

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To dig deeper: Benzing and Renfrow article

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Heliotropium angiospermum

Boraginaceae

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Scorpion Tail is a native mystery, easy to find but tough to understand distributed in South Florida, South Texas, the Caribbean, and South America. Gardeners like it for its delicate charm.  The ancient Mayans used it in formulations against gastrointestinal infections.

What I find remarkable is its precision.   Along that “scorpion tail” inflorescences the flowers are lined up perfectly by age, the youngest at the tip.   Toward the base they are post-opening and get older, with only one flower open along the entire wand, the ones further out being all buds, and the ones toward the base all being developing fruits.  

The flowers are visited by butterflies but not much.  I have it in my butterfly garden at home, and I never detect a visit there, despite scores of butterflies lighting on other flowers all day long.    There is “no way” every Scorpion Tail flower receives a butterfly visit. [Note added after this blog incubated. My friend and native plant expert Dane Boggio mentioned seeing a Cassius Blue on one recently, and we looked at several Scorpiontails in Lake Worth 8/7/2021. While we watched, a number of honeybees visited, as did one small Hairstreak (?) butterfly. Dane and a reader comment below caused me to suspect that I may have overstated the rarity of butterfly visitation, all depending on what is meant by “rare.”]

Yet every flower forms a fruit.    That suggests self-pollination, and various botanists have surmised selfing in varied species of Heliotropium.   But who knows…the floral biology of H. angiospermum has never been studied, so let’s be pioneers and take a stab at it.

The open flower looks normal enough, with a ring of five well separated pollen-making anthers around the opening inviting a butterfly to do what the birds and the bees and the butterflies do.

The next day is more interesting.  The flower does not merely close, but the petals clench in tightly like a clenched fist.   Cutting open such a clenched flower shows the anthers (white line in photo) now mashed together, the broad but short mushroom-shaped stigma (black line) below them.  Perhaps significantly,  alongside the stigma is alongside a brush of hairs (red line).   Looks to me like pollen might fall into those hair, while the flower is open or later, and then the clenching upon closing might push the hairs up against the stigma like a pollen paintbrush.

Hmmmmmm…it might work that way (or not),  and we’ve had a fist peep at a question nobody has explored to date. Call it a working hunch.

Dielis dorsata (Campsomeris dorsata)

Vespidae

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Last several days I’ve been enchanted by a patch of Skyflower (Hydrolea corymbosa) in the mud at the edge of a bald cypress swamp near my home.  The wildflower has sky-blue blossoms.  

I’m not the only one who loves those blossoms.    Sit down there for 15 minutes and watch a parade of pollinators:  bees of many types, skippers, and wasps.

The visitor that raised my eyebrows is a wasp, easy to spot by its orange abdomen, Dielis dorsata, aka the Caribbean Scoliid Wasp, recently “written up” by UF entomologist Anthony Abbte and collaborators in the Florida Entomologist. Most of what I have to say here is a “book report” on that.

Today’s wasp is in a group that parasitizes Scarab Beetles by burrowing into the earth to sting and lay eggs in the beetle larvae. Quite a feat! And a useful skill.   Such wasps were introduced into the U.S. deliberately to control Japanese Beetles, disappointingly.  Japanese Beetles are not much of a problem in S Florida but sugar cane pest beetles are. Today’s orange wasp was introduced in the 1930s from Puerto Rico to attack those.

It took hold, and mission-crept beyond sugar cane.  The study mentioned above found the wasp entrenched in Miami-Dade County and some in the greater Tampa area, probably preying on grubs in residential and sports turf.  An isolated occurrence was notably far north, in Osceola County.  None in Palm Beach County, well, not until it turned up pollinating Hydrolea this week.

The worry with importing pests of the pests, of course, is that sometimes the introduced warriers don’t know to limit their destruction to the target pest species.   Beyond the scope of this little blog, there have been cases where introduced  biocontrol agents “went too far.”    I’m sure we’d all like healthy sugar cane, and reduced grubs in the turfgrass as a surprise side-benefit.   I’m just hoping that Dielis dorsata is “behaving itself” in the Cypress Creek Natural Area, pollinating Skyflower and messin’ only with “bad beetles.”

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Nymphoides aquatica and Nymphoides cristata

Menyanthaceae

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Out and about today, the pretty encounter was with Crested Floating-Heart floatin’ & flowerin’ along the shores in the Winding Waters Natural Area. They look like little Water-Lilies but are unrelated, merely sharing convergently a similar lifestyle and consequent appearance. Crested Floating Heart, N. cristata, is not native. It appeared in S Florida maybe 30 years ago, probably dumped from aquariums,  has spread to other states, and in places can overdo it a bit. 

Crested Floating Hearts is so similar to the native Floating Heart, N. aquatica, the two can be a challenge to distinguish.  Most obviously, the crested invader has a wavy white wing like the fin on an eel rising from each petal.

Nymphoides cristata tends toward slightly more-elongate leaf blades.  Trouble is, the size of the “fin” varies, and S. aquatica has a ridge on its petals.   The similarity of the two species is certainly one example of many of close similarities between plants of eastern North America and eastern Asia.

A more subtle difference is in the flower structure.  Nymphoides aquatica is dioecious, that is, has separate male and female plants.  Nymphoides cristata, by contrast, has bisexual flowers with both sexes together, at least so far as known in Florida.   Across its much broader range, the breeding system varies, and having been introduced to Florida more than once, it may have some surprises if studied statewide.   The flowers in Winding Waters today were bisexual.

In the aquarium world, Nymphoides aquatica has the name “Banana Plant,” because the floating plants form banana-shaped roots in the water up near the leaves.    Nymphoides cristata has tuberous roots too, but thinner.  In both species, the tuberous roots break off and disperse the plants.

In tropical Asia where N. cristata is native, it has some value as a food, although please do not try that, as it also contains bioactive compounds, including ephedrine and coumarins.   In years of studying plants, you see just about every conceivable use, but one “new to me” is grinding the plants with oil to use as a salve on bug bites.    I’m tempted to try that.

Conyza canadensis (aka Erigeron canadensis)

(Conyza is an ancient name for flea-repellent powder from a similar plant.   Conyza canadensis grows from Canada to the tropics.)

Asteraceae

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The point here today is to look at the “world’s fastest evolution,” flashing right before our eyes with the native plant Canadian Horseweed.  The species is arguably sort of attractive sometimes.  John Bradford’s close-ups of the flowerheads bolster the iffy case for a little pretty.

The plant starts out as a rosette sprawled on the ground, then rises, often symmetrically and branch-ily, to, oh say, 4-5 feet with leaves at right angles from the stem, and a million little flower heads, white with yellow centers.   The fruit looks like a tiny seed on a parachute.   They blow forth and multiply,  and to help take hold far afield, the flowers can self-pollinate.

Saying Canadian Horseweed is native is an understatement.    It grows across most of North America, and is distributed further, naturally or unnaturally, pretty much around the green earth from near-Arctic to the tropics.   It is everywhere, lots and lots of it, welcome or not.  

Canadian Horseweed is a fearsome pest in farms fields, plant nurseries, orchards, vineyards, and everywhere plants are grown.   They thrive under any conditions: wet or dry? Yep, even desert. Acid? Yes. Alkaline? Sure. Sun? Of course. Shade? OK.  Terrible soil?  No worries. Rich soil? Even better.  I could go on even more boringly, but you get the idea.   Hey, if you have trouble making plants grow, try a Horseweed!  The species is allelopathic, that is, it can suppress other plants, sometimes reducing crop yields as much as 90% by some combination of competition, altering the soil ecology, and allelopathy.

Canadian H-weed got real interesting with the advent of Round-Up Ready Soybeans.   Around 1996, soybeans resistant to the famous herbicide Round-Up came into common use.  The idea was if the crop is immune to the herbicide, then spray a lot, spare the beans, and smite the weeds.  Just three years later, in 1999 there were Round-Up resistant strains of Canadian Horseweed in multiple states.  And we thought evolution takes eons!

If I spray a field inhabited by 10,000 Horseweeds and 9,999 die, that sole survivor has some mutation that renders it immune.  And remember they are self-pollinating, so that lonely mutant can spawn a documented 200,000 seeds, many, most, or all with the resistance mutation.   Repeat that a few generations, and poof!, we have just evolved a whole new strain untouched by Round-Up.  Such untouchable strains are now widespread.

No problem we say, if Round-Up won’t work, switch poisons.   That occurred, and now Horseweeds (not all of them everywhere) are resistant as follows:

Speaking of mass tort attorneys trolling TV for clients, Horseweed is also resistant to Paraquat (and its cousin Diquat).  Atrazine got into litigation when a University of California Professor raised an alarm about deformed frogs, implying deformed humans you might say.   Horseweed resistant?  Yes, as is so for the similar Simazine.

A whole family of herbicides is based on similarity to the plant nutrient compound urea.  Horseweed is resistant to several of these, including Diuron.  A comparatively recent family of weed killers, the sulfonylureas may be the solution?…oops, nope, them too.

All this instant evolution suggests a remarkable ability for the seeds to wander and mix genes with other Canadian Horseweeds.     Not only are the seeds wind-dispersed like so many plants, they are outta this world.   The teensie parachutes zoom at 60 feet/second over flyover country in the atmospheric “Planetary Boundary Layer.”    And, come to think of it, a plant does not have to disperse seeds to disperse its genes, given that pollen grains can have the same effect.  Although the research is preliminary, it seems that may happen too, even if CHW is mostly insect-pollinated.

Why called “horseweed”?  Among many historical uses, the plant was a medicine for horses, probably the reason for the name.   Of those many recorded uses, and I have not tried it personally, Seminole men wishing to be rid of their wife rubbed it on their bodies (on their own bodies, I think)….I don’t know if it worked the other way around too.

Quercus laurifolia

Fagaceae

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Palm Beach County residents know Live Oak (Quercus virginiana) as the dominant street tree hereabouts and far beyond, and present in many natural areas.   Our second big-growing oak, Laurel Oak, is encountered less often in landscaping, and is mostly restricted to wet habitats.  (Although gorgeous and happy to grow, Laurel Oaks have comparatively short lives, suffer from internal decay, and have medium-low hurricane resistance, all unfortunately limiting the ornamental use of this lovely tree.)

The best places to see Laurel Oaks are in lowland alluvial river floodplains, including Riverbend Park in Jupiter.   The largest individuals I’ve personally noticed in Florida, the trunks 4 feet or more in diameter, are along the Hillsborough River near Tampa. Fact is, the Florida State Champion, almost 6 feet in diameter, lives along a creek in the Hillsborough River watershed.    The largest specimen on Earth is in Virginia, about 8.5 feet in diameter.   Although not competing with those giants, the Laurel Oaks along the Loxahatchee River in Riverbend Park are respectable enough. 

Laurel Oaks differ from live oaks by having hairless leaves, and having the mature acorns sit directly on the branches, not having separate stalks of their own.  Compared with Live Oaks, the trunks of Laurel Oaks are straighter and more upright, and lichens love them including the small twigs.  Individuals can be symmetrical, and can be bushy from the top all the way to the ground.

Many floodplain tree trunks have broad bases with lobes at the attachment points of massive shallow horizontal roots.  Thick radiating roots are unwelcome when Laurel Oaks are cultivated close to pavement. 

In river bottoms and similar places, the growth is strongly seasonal, which shows up in the wood grain, as does that tendency to early decay, making wood useful where irregular patterning is an aesthetic “plus,” such as counter tops.

Living in a periodically flooded habitat poses special problems for the trees, which must withstand the associated stresses of unrooting by flooding, and drowned roots, and at the same time be able to recolonize to replace lost individuals.    They are experts at spawning new seedlings, as put so well by an article from 1916:

The tough leaves have a quirk of interest to climate scientists.  Cellular patterns on the leaf surfaces adjust visibly to wet vs. dry weather.  The patterns remain visible on the waxy coating even years after the leaves have fallen to be preserved in wet, low-oxygen peat under the trees, deposited in layers by annual flooding. Their relative age is determined by their depth of burial.   The same patterns are preserved with precise dates on museum specimens, which can date back into the 1800s or even before.   Such precise “wet-spell/dry-spell” fingerprints allow reconstruction of weather patterns in relation to specific years, and in relation to geography.

Although I have no awareness of relevant reports on Laurel Oak itself, oaks in general are regarded as often strongly allelopathic (able to suppress competing plants).  Some of the individuals in Riverbend have almost clear ground beneath: allelopathy? shade? leaf litter?