Partridge Peas and Ambivalent Bees

Partridge Peas

Chamaecrista fasciculata

Caesalpiniaceae

Okeeheelee Nature Center is in Okeeheelee Park near the Florida Turnpike in West Palm Beach.  CLICK   The 2.5 miles of trails criss-cross through dry pine woods interspersed with ponds and marshy areas, a pleasing natural reserve in the middle of our urban area.  So John and I went there today with cameras in hand.

Okeeheelee

Each time and place has one standout species.  Yesterday it was Partridge Pea in splendid flower over the river and through the woods.   Looks misleadingly a little like a fern, well, sorta.  More like Sensitive Plant but no, and not that sensitive.  Resembles a Cassia plenty, and has historically been classified as one.  A little weedy, Partridge Pea is adaptable and variable, basically an annual or slightly woody subshrub with ferny compound leaves, butter-yellow flowers, and flat pea pod fruits.  It’s everywhere, especially dryish disturbed sites, but sometimes where it is moist, in the sun or under the understory—-you can’t miss it.  Recently burned places are good places to look.   The species ranges from Florida across most of eastern and central North America.

Partridge Pea (by JB)

This is one of many local species equipped with foliar nectaries to feed ants.  Look on the stalks of those compound leaves for a little nectar gland on each leaf.  The plant feeds ants, and the ants provide Security Services.  Lots of plants and ants symbiose; on the same outing we saw similar glands on the leaf stalks on Bracken Fern, on a Senna at the Visitor Center, on Caesarweed, and on Cocoplum.

The gland is near the base of the leaf-stalk (JB)

The flowers are open just one day.  Pollination is exclusively by bees, and then only those whose “buzz” has the correct frequency to cause the pollen to puff out of pores at the anther tips.  The stamens (pollen-producing organs) are of two lengths, the shorter ones feeding pollen to the bee, and the longer ones depositing pollen onto it.

This photo (by JB) shows the short stamens and the longer ones.  The single structure angled to the right is the (female) style.  Note how the style is angled to the right, and read on.

 

Researchers examining Chamaecrista using electron microscopes have found the stigma (pollen-receiving organ) to be in a small cavity covered in hairs, and to require the “right” buzz for pollen reception.   Preliminary indications (or conjectures) are of a liquid in the cavity that “comes forth” when buzzed properly, able then to snatch the pollen in glue.  (This glue resembles the pollination droplet characteristic of “primitive” seed plants.) The wrong bug carrying the wrong pollen isn’t going to contaminate these very exclusive flowers.

Oddly, buzz flowers tend to have the flowers in an alternating “mirror image” left-right-oriented sequence.  Looking at the flower face-on, the styles (and possibly stamens) are either bent to the left or right.  This link CLICK shows the right-face, left-face, right-face etc. alternation of the skewed flowers.  Check also the link in the notes below.

The alternation pattern is called enantiostyly (ee-NANT-ee-oh-style-ee) and is known in varied unrelated plants.  In at least some species, the left-skew, right-skew pattern is under the control of a single gene, functioning as a toggle.  What enantiostyly is all about is a little controversial, and possibly more than one benefit, and is a matter of current research.   For a short explanation, pollen placement and removal on the bee is precise, and the bilateral application increases efficiency by addressing both sides of the bee.

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Notes:  Another nice link showing the left- right- skewed flowers: CLICK

Even the opening pods have a mirror-image thing going on (JB).

 

 

 

Glade Lobelia

Lobelia glandulosa

Campanulaceae (Lobeliaceae)

 

Lobelia feayana (by John Bradford)

 

Yesterday John and George trekked under the hot sun down a dirt road in the large wetland area west of Jupiter, a zone of marshes, depression ponds, and wet pine woods.  There’s a special treat there—a flowing gurgling glimmering brook with clear water and tiny fish, lined with all your basic wetland plant species.  A natural garden of delight.  (The horseflies too were delighted to have some fresh meat. Come along.)

And no garden is completely delightful without a Lobelia, as lobelias are among the most widespread, diverse, colorful wildflowers and cultivated horticultural selections around the garden globe, over 350 species.  Today’s Glade Lobelia is a pretty blue wildflower reminiscent at a glance of last week’s Scutellaria.  And just as Scutellaria had a gimmick, the scute, lobelias have their own odd flower feature.

Lobelia glandulosa (by JB)

In lobelias, there are two linked oddities:  the flower tube is slit for most of its length, and the five stamens are fused into a tube encasing the style and stigma.   As the flower opens the stigmas are  hidden within the anther tube, making the flower effectively male (pollen producing) at first, then later the stigmas emerge past the end of the tube to render the flower female.    (These features are notably similar to similar structure in the Aster Family.)

This link shows the anther tube removed from a flower.  The style and stigmas are inside the tube  CLICK

Lobelias have hummingbirds, butterflies, and who knows what else, as pollinators, mostly bees no doubt.  In most other flowers the pollinator has to fit within the petal tube, like a car entering the garage.    But in Lobelia, the visitor pulls open the split petal  tube to gain access to inner flower, contacting the anthers or stigmas through the slit.   This link shows a hummingbird probing the slit flower while having its head tapped by the anther-stigma unit.  CLICK

As a student, I remember being wowed at a more northern species, Lobelia inflata, sometimes called Indian Tobacco.  (A dumb name since true tobacco itself was a Native American bad habit.)  The professor said, accurately, that people smoked this species and used it in medicines for the several alkaloid drugs it contains, most interestingly for smoking-cessation and for curbing other addictions.   That was in the 70s, and research has marched on. It turns out the dominant alkaloid, lobeline, interacts with more or less the same brain receptors as nicotine, although they are not similar chemically.  There’s perhaps something potentially useful going on there, and lobeline interferes with the neurotransmitter dopamine.

One of these days I’ve got to quit smoking!

 

Hydroballochory Happens!

Helmet Skullcap

Scutellaria integrifolia

Lamiaceae

Skullcap 3/28. Today’s photos by John Bradford.

In Halpatioke Park in Stuart today (CLICK) John and George encountered a mighty fine mint, Helmet Skullcap, Scutellaria integrifolia.  The species ranges from New England through Florida as one of 350 Skullcap species  all over the world.

Try to find a genus more steeped in medicinal history, homeopathy, alternative remedies, herbal products,  and expensive little bottles, right up to modern scientific medical research.  Skullcaps have served against so many ailments in so many cultures for so many centuries to make a list is as pointless as listing awards won by Elizabeth Taylor.   Just name your favorite malady.   But maybe to curb the fervor for “ingest every wild plant,” Scutellaria extracts cause liver damage, impair membrane functions, and suppress enzymes.

Why name a pretty little wildflower Skullcap?  That stems from the same source as the botanical name Scutellaria.  Let me explain:  The sepals in this and other mints are fused edge-to-edge to make a cup at the flower base.  The proper name for the little cup is the calyx tube.  In this useful link, the tube is labeled, “sepals fused.” CLICK

The defining feature of Scutellaria is that on the outer upper surface of those fused sepals (calyx tube) rises a bowl-shaped shield, or scute (plate).   The scute often looks like a beanie, hence the plant name.

The scutes at the flower bases. Little green “beanies” jutting up from the green cup formed by the fused sepals, the calyx tube.

But why should that wacky scute exist?  To answer that we need a little general background on the Mint Family flower and fruit structure.  We’ve already met the fused sepals, the calyx tube.  As the flower transitions from the flowering phase to the fruiting phase, the petals fall away, the calyx tube remains in place, its scute enlarges, and the fruits remain as four tiny dry “seeds” inside the calyx tube, which is usually more or less horizontal on the old flower spike.   The sepal cup is spring-loaded at the base, so picture a nearly horizontal cup with four ping pong balls inside, attached to a vertical pole by a spring.   When raindrops strike the scute on the top side of the tipped cup, let’s call it now a splash-cup,  the falling drops bounce the cup. The bounce pops the “seeds” out for dispersal.   That’s  hydroballochory, dude.  This link shows four seeds  ready to bounce. CLICK

 

 

 

 

 

Dwarf Huckleberry

Gaylussacia dumosa

Ericaceae

Yesterday John and George experienced Savannas Preserve State Park near Port St. Lucie and featuring marshes, wet prairies, scrub, low pinewoods, and all the associated biodiversity. CLICK to visit.  The area is rich in members of the Azalea Family, the Ericacaceae, including today’s little oddity, Dwarf Huckleberry.     The Dwarf Huckleberry was the show-plant of the day, in full bloom on high dry sandy spots hanging out with its relatives tarflowers and blueberries.

Dwarf Huckleberry. All photos today, except the damaged blueberry flowers, by John Bradford.

Two things about Dwarf Huckleberry deserve attention in Treasure Coast Natives.   Each has an historical component.

Historical Thing 1.  Odd distribution.  If you’d like an example of a case proving species are tough to define, here it is.  Harvard Professor Merritt Lyndon Fernald who reigned as King of northeastern U.S. botany for the first half of the 20^th Century, studied our huckleberry and perceived one species with two varieties distributed eye-poppingly from Newfoundland to very nearly where John and I saw it yesterday.  Fernald dubbed the northern populations Gaylusaccia dumas variety bigeloviana, noting only minor differences between these and the southern variety (var. dumosa).   The truly interesting part was an ecological component, with the populations at the northern end of the distribution mostly in bogs, and those to the south more prone to dry sandy habitats. (It might be worth mentioning that bogs, with extreme acidity, can be “physiologically dry.”   There are other cases of split bog-upland distributions.)

Yesterday at Savannas.

This single-species view prevailed for almost 100 years until a new interpretation popped up in 2007, granting the northern end of the bipolar complex to secede as Gaylusaccia bigeloviana.  The fuzzy geographic border between G. bigeloviana and the remaining G. dumosa runs across the Carolinas.   So in short, a classic botanical situation: a plant group stretched out over a long distribution, with some differences pole-to-pole.   One widespread species with two varieties?  Two species?  Something else?  You decide.  Want to argue? No thanks—pretty much a fool’s argument really.  No matter how you slice and dice it, dwarf huckleberries from bogs in Newfoundland look like plants John and I saw in Savannas Preserve State Park.  (For northward peek,  see p. 5  CLICK)

Historical Thing 2.  Crimes against nature.  Back in 1888 botanist L.H. Pammel—noteworthy as an advising professor to George Washington Carver—published a long treatise on the “perforation of flowers,”  that is, on holes drilled into blossoms by insects to rob nectar, as opposed to entering properly.  Nectar thieves!  One of his examples was, yep, Gaylusaccia dumosa burgled by five species of wasps, as

Related to Huckleberry, these Blueberry flowers have been perforated and robbed. Prof. Pammel would like this photo, which I’ve borrowed from Google Images.

observed at Orlando, Florida, nipping holes in the side of the bell-shaped petal tube.  The circumstances of that observation in Orlando ca. 1888 must have been interesting!  Do wasps consume nectar?  Yes, some do,  including sting-less males of certain species.

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Huckleberry FAQ’s

1. What does Gaylussacia mean?  Joseph Gay-Lussac (1778-1850) was a prominent French chemist.  Dumosa is a specific epithet applied to plant in thickets.

2. How do Huckleberries differ from their cousins, the Blueberries?  Blueberries have a variable number of seeds loose in the berry.  Huckleberries have 10 seeds in the fruit, each seed in a little hard case.

3. Where can I see a modern classification of huckleberries?  http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=113345

Our species, color plate from Curtis Botanical Magazine

 

Saw Grass

Cladium jamaicense

Cyperaceae

John and George failed to hit the wilderness this week for diverse reasons, including a mandatory Friday campus meeting for George, and John completing the revision of our grass web site  CLICK

The website adventure has resembled crossing the Everglades in a Speedo,  bled by typo mosquitoes, wrestling tech support pythons, and sliced raw by Sawgrass.  John did 90% of the work, and the new revision is a breath of fresh air with better info, old editorial sins corrected, updated photos,  and improved performance.   In honor of the occasion, today’s blog must of course be Sawgrass.  SAW HERE

It is the sworn duty of anyone writing about Sawgrass to point out quickly that we’re talking about a sedge, not a grass.  The name is not 100% misnomer though, the “grass” saws with gusto.

All photos today are Sawgrass by John Bradford.

When I think of Sawgrass, I think of the Everglades or maybe picking up cool kicks at 40% below retail at Sawgrass Mills.  SHOP HERE  The big sedge is not just a Florida possession however.   It ranges from Virginia to Texas and into the West Indies;  after all, the name is “jamaicense,” not “floridacense.”  And, oddly, there is a population in Hawaii regarded as indigenous.  Sawgrasses get around.  The “seeds” (achenes) float, and they mature a little fleshy presumably promoting bird dispersal.  With species borders debatable, there are Cladiums from Mexico to northern Canada through Europe all the way to Australia.  (CLICK for one classification.)  Cladium mariscoides, a more-northern species with harmless foliage ventures as far south as North Florida.

Beyond the floating fruits, how does one species fill vast areas, quickly and competitively after fires and hurricanes?  Like many sedges, Sawgrass has rhizomes protected in the moist soil for spreading and regeneration, ho hum.  More interesting is an ability that crops up here and there among  sedges, formation of baby plantlets in the inflorescence, not from seeds but clones of the mother plant—pups or bulbils.  You can see similar clonal babies at the tops of many Agave plants or on “Walking Iris.”  Sometimes the babies take root when their inflorescence bends to the ground, allowing the sedge to “walk” across the land.

The sawtooth leaves give today’s plant its reputation as a bloody gauntlet to traverse.  But why do the leaves have those teeth?  The kneejerk answer is to deter eating, but maybe—just a hunch—there’s more to the story.  What’s the biggest threat to a plant that fills acres of wetland?  Herbivory?  Maybe, but competition from surrounding vegetation, even other Sawgrasses, is conceivably a more pressing issue.   Can those infamous leaf margins slash adjacent vegetation as they lash about  in the wind?

Sawgrass is chiefly a freshwater species with limited salt tolerance.  As saltwater intrusion boosts salinity in some habitats, Sawgrass loses market-share to more salt-loving competition.

The famous competitive threat to Sawgrass is by Cattails which have taken over in places.  A much-discussed contributing  factor is artificially high phosphorus levels from pollution entering the naturally nutrient-limited Everglades systems, tipping the competitive balance.  But life is never simple.   Cattails and Sawgrass share an adaptation to flooded soils – air channels called aerenchyma (air-EN-caw-maw) in the roots bestowing upon both the super power of flood tolerance.   But according to research, Cattails have greater tolerance, and are perhaps more robust to soil toxins.  Cattails are favored, it seems, where water is impounded deeper and longer than Sawgrass prefers.  Of course you could write a book about disturbances to marsh ecosystems and consequences to the species balance.  Chapters in the book would concern salinity, nutrients, toxins, water levels, and fires.  But all of that may be subsumed under the final chapter:  Sawgrass marshes are predominantly coastal, and sea level rise from Global Climate Change may have the last word.  Why worry about a few cattails?

 

Flip-Flopper Flowers

Spurred Butterfly Pea

Centrosema  virginianum

Fabaceae

John and George devoted much of the day to revising our Grass and Sedge web site www.floridagrasses.org (you will still see the “bad” old version), but today was too enticing to remain cooped up inside, so we took a botanical look at the Hawk’s Bluff Trail, a scrubby coastal dune area near Jensen Beach, and part of Savannas Preserve State Park.  Any witness would testify that the flower show today was Butterfly Pea, Centrosema virginianum.  Hundreds in bloom decorated the trail.

These are curious members of the Pea Family, with an odd twist.  To establish comparative context, let’s start with normal pea-type flowers.  There are  five petals (see the diagram, top yellow images).

• A “banner,”  which is a showy billboard rising up above the rest of the flower
• Two “wings” which stick out straight from the center of the flower.   These paired petals can be small or sometimes tough to see.  They are not important today.
• And a “keel” at the base of the flower made of two petals joined to form a boat-shaped envelope, open-side-up serving as landing platform for bees.  The keel contains the business parts of the flower, the pollen-receptive stigma and the pollen-making anthers.   When a bee lights on the keel, the keel bends down, and the stigma and anthers pop up to contact the underside of the visitor.   This sort of normal pea flower is detailed in an earlier blog
  

Now, turn the beat around.  In Centrosema (and in similar Clitoria) the flower is essentially the same but flipped, with the keel on top and the banner at the base, the banner now serving as landing platform. When an insect visits these flowers, the keel with its stigma and anthers is above the bee.

Top: Standard pea-type flower
Bottom: Flipped Centrosema flower

Side view, with X-ray vision, of Centrosema keel and the style hidden within

A similar flip-flop is seen in Orchids.  In a minority of Orchids the big showy petal (called the labellum) rises up just like the banner in normal Pea Flowers.  And the stigma/anther unit (called the column) serves as landing platform just as the keel hiding the stigma and anthers does in a standard Pea Flower.  (Such Orchids are called non-resupinate Orchids.)

The majority of Orchids, however, are flipped 180 to resemble Centrosema, that is, with the labellum (banner) as the welcome mat, and the stigma-anther unit arching above.   (Such Orchids are called resupinate Orchids.)  Here are some resupinate Orchids.   CLICK

You can see the odd resemblance of resupinate Orchids to Butterfly Peas.  And so can so-called “Orchid Bees,” that is, Euglossine Bees, caught in the act occasionally of visiting Centrosema.  BUZZ here  Is the Centrosema floral-flip a mechanism to poach Orchid bees^*?

Those flowers are flip-floppers!

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Notes:

^*Don’t let me over-state the “Orchid Bee” -Centrosema hunch, which has occurred to other botanists before today.  Euglossine bees are not limited to Orchids (and to Orchid lookalikes), and Centrosemas do have a variety of floral visitors.  But still, Orchido-centric bees visiting Orchid-mimicking flowers is fertile hunch fodder.

John and I enjoyed the common Centrosema virginianum,  but there are additional Butterfly Peas in Florida. Centrosema arenicola is state-listed as endangered; most of its range is Central Florida.  Another, presumed to be a garden escape, is Centrosema sagittatum.  (There are similar species of Clitoria also.)

Being good legumes, Centrosemas serve as cover crops,  green manures, and rubber, and as livestock fodder.

 

Orchid Weeds, Fungal Needs, and Wind-Blown Seeds

Lawn Orchid, Soldiers Orchid

Zeuxine strateumatica

Orchidaceae

St. Johns Wort in JD Park Feb. 28. All photos today by John Bradford

When I think of Orchids, I think of jungle epiphytes, or exotic fieldtrips,  or corsages, or my brother’s flowery greenhouse (and the morons who broke into it recently probably looking for pot, only to leave the doors open in an 8-degree Michigan night).

Or, more botanically speaking, I think of the largest plant family that has splintered itself into maybe 30,000 species famous for specialized habitat niches, dedicated pollinators, restricted fungal associates, and narrow geographic ranges.  In short, voted, “least likely to be weeds.”

That “it’s not us” perception seems fundamental to the enormous world trade in Orchids, shuffling the Franken-hybrid and species plants all over the place surprisingly unrestricted and with little thought to potential escape into natural habitats.  Too bad that invasive exotic Orchids exist and seem to be getting worse.

Cheesy Toes in JD Feb. 28.

Which Orchids dominate the commercial and hobby trade?  Answer:  The ones with broad tolerances and flexible needs.  Same reason so many other exotics have become invasive.  And much like the spores of weedy ferns, Orchid seeds are dust blowin’ in the wind.  Every warm climate worldwide has Orchid enthusiasts, and cultivated  Orchids are getting loose with documented adverse effects, for instance, disease spreading from invasive species to native Orchids.  Epipactis helleborine is a good-old weedy species across cool latitudes.  Disa bracteata is a self-pollinated nuisance ground Orchid in Australia.   And new pests are turning up, perhaps most alarmingly in Hawaii.

Lawn Orchid, Zeuxine, in JD, Feb. 28

Even though most Orchids are too constrained by their local pollinators and fungal associates to venture untended outside their normal ranges, some are self-pollinated or able to form seeds unpollinated.  Some find new pollinators, such as the Brazilian Parana Cowhorn Orchid Cyrtopodium flavum (C. polyphyllum) sneaking into Florida aided by an exotic bee (reported in Botany 88: 290. 2010).  Some weedy Orchids bring their fungal associates with them, or find new consorts.

My three most recent Orchid encounters in local wild areas were weedy Orchids, probably all  non-native species. (The exact nativity of species with dustlike wind-blown seeds, and of weedy species in general can be unclear.)  On our class field trip yesterday a sharp-eyed student spotted a pretty Orchid.  How nice!  At that moment I was unsure of the identity, but at home later with resources in handr, realized it was Eulophia graminea, an invasive Asian species.  In the same class, the students had previously spotted Monk Orchid, Oeceoclades maculata, an invasive weedy reportedly alien species CLICK with distinctive blotched  (maculata) foliage.  This weed extends from Africa (see comments) to Tropical America, and into the Caribbean and Florida.   I wonder if Global Warming is helping a northward progression, only a vague hunch.  A quick search of the Florida Atlas of Vascular Plants turns up a baker’s dozen non-native Orchids.

The feral Orchid trend continued today.  John and George just can’t stay out of Jonathan Dickinson State Park—such a lovely destination in the cool sunshine with Pawpaws, Gallberries, St. Johnsworts, Water Lilies, Silkgrass,  and Marsh-Pinks in bloom.

As we stepped out of the car, hey look, an Orchid.  Lawn Orchid, Zeuxine strateumatica it was.  The invasive exotic Old World species decorates lawns and disturbed moist spots in several southern states.  In cultivation it can be medium-magnificent.  When escaped, it looks pretty but unassuming.

The species ranges more or less naturally (?) from the Middle East to the Pacific Islands, and has spread beyond.  The first U.S. report dates to 1936 near Fellsmere, Florida.  Harvard University researchers in the 1940′s (see citation below) surmised speculatively that the Orchid hitchhiked here with imported Centipede Grass around WWI but failed to spread at first because its usual fungal associate was not sufficiently established locally.  By almost WWII, the necessary fungus, Rhizoctonia mucoroides, had a local foothold, and the Orchid-fungus duo spread  with alacrity.  Dig this:  The Orchid’s seeds germinate only in the presence of the fungus, which researchers isolated from the Zeuxine in Florida and in its native Java.

Multiple botanists explain Zeuxine’s viable seeds without a known local pollinator as probable self-pollination and/or  seed formation without benefit of pollination.  Such (apomictic) seeds contain a clone of the mother plant.  Determining if the plants self-pollinate or produce seed-borne clones is a feasible student research project.

Lawn Orchid comes and goes mysteriously.  John and I often park where we encountered it, but have never seen the little imp there previously.  The first time I saw the species was in masses behind a store in Jupiter.  It vanished.  I wonder if the “here today gone tomorrow” behavior explains Linnaeus’s name, “Orchis strateumatica,”  with strateuma in Greek a roving band or regiment of soldiers.  The plant’s basic lifestyle explains the peek-a-boo:  There is an underground stem rooted at one end, with the opposite end capable of rising up and flowering.  After coming up like a periscope, the flowery end dies down out of sight.  At that time the fungus presumably sustains the subterranean stem saprophytically until some environmental cue says, “up-periscope.”

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Note:

An account of the biological side of the Zeuxine strateumatica invasion appears in Mycologia 34: 380-390. 1942.