August 11, 2008
SESBANIA ON SANDY CREEK
When I returned to Mississippi in early June, emerging from wet sand all along nearby Sandy Creek's shoreline were abundant, flowerless, ferny-looking, ankle-high herbs whose thousands of robust, feathery leaves created a striking presence. Over the summer I've watched them grow, each week a few inches higher, more and more eye-catching, until now they're seven to ten feet tall, so different from other plants along the creek and with such a dignified presence that they seem otherworldly, like proud Roman centurions at attention among the throngs of simple plebeians. Two seven-ft-tall ones are shown at http://www.backyardnature.net/n/08/080811sb.jpg.
The plant is SESBANIA HERBACEA, known by such names as Hemp Sesbania, Coffee-weed, Indigo-weed, Peaweed and a host of others. It's still too early in the season for most Sesbania herbaceas to be flowering but a couple of plants among the dozens on a sandbar where I rested this week bore flowers, and you can see them at http://www.backyardnature.net/n/08/080811sc.jpg.
For that picture I removed the near side of the "banner" of the flower on the right, and its nearest "wing" so you can see the neat way its "keel" curves upward inside the blossom, terminating with a splash of red. Those words banner, wing and keel are special terms used to describe the unique flower structure of Bean-Family' papilionaceous flowers, for Sesbanias are Bean Family members. The "banner" is the top petal, which in Sesbania's case has enlarged and folded downward so that it almost encloses the whole blossom. "Wings" are the two side-petals, which sometimes flair out like insect wings, and the "keel" is formed by the five-petaled blossom's two lower petals, which join together to form something like the keel of a boat.
Despite the plant's aristocratic appearance it's a native species, and despite its size (to 13 feet, 4m tall) and woody-looking trunk, it's an herb, dying back each winter. If you pull up a plant you'll find warty-looking, nitrogen-fixing mycorrhizal nodules on its fibrous roots, so this plant definitely contributes importantly to Sandy Creek's riverside ecology.
Still, in Arkansas it's considered a noxious weed because it competes with rice in flooded rice fields. The species is native to the US Deep South, but sometimes shows up as far north as New York and Pennsylvania.
INDIAN WOOD OATS
Speaking of a dignified presence, the grass shown at http://www.backyardnature.net/n/08/080811uu.jpg is one of the most graceful, common and easy-to-identify of all wild grasses. It's CHASMANTHIUM LATIFOLIUM, going by such English names as Indian Wood Oats, Wild Oats, Spangle Grass and many others. It used to be placed in the genus Uniola.
In the picture the plant arches from one of Sandy Creek's steep, overgrown banks, its leaves and flower heads quaking in a soft breeze flowing up the stream. Those flattish items at the end of the arcing stem are its flower heads.
At http://www.backyardnature.net/n/08/080811uv.jpg you can see a close-up of a spikelet.
When I started learning my grasses back on the farm in Kentucky, this was the first species I was able to identify with certainty using technical keys, so I've always had a special place in my heart for this species. It was my "first grass" because its flowers are much larger than those of most grasses, so the parts were much easier to see and interpret than the flowers of most grasses.
For example, in the above picture notice that the spikelet consists of about ten teardrop-shaped items, which are the actual flowers, or florets. The very top of the spikelet is crowned by small, leaflike scales. These two scales are "glumes," and when you're identifying grasses the glumes' disposition, size, texture and other features are critically important.
Each of the ten or so florets below the glumes is encased in a scaly, scoop-shaped husk referred to as the "lemma." Lemmas are analogous to the calyxes of a regular blossoms. Indian Wood Oats' lemmas, my Gray's Manual of Botany says, are "hispidulous on the winged keel." It's referring to the fact that the lemma's flattish sides are folded together beneath a crease so sharp-edged that it's like a wing. "Hispidulous" describes to the tiny, silvery, slender hairs barely visible along the lemmas' winged keels.
Inside the lemmas are even tinier and more elegant details, for that's where the sexual parts are.
In fact, studying grass flower-anatomy thrusts your mind among such unforeseen and pleasing-to-the-eye details that one can't help but to be cast into a good mood. Inside the flower of every grass there's a wonderland of exotic forms, textures, colors and processes.
You might enjoy looking over my Grass Flower Page at http://www.backyardnature.net/fl_grass.htm.
THE BIG CHANGE, AGAIN
Wednesday I broke my usual routines centered around the delightful little trailer with its oversized porch beneath shadowy oaks, abandoned the view through green treetops into blue sky, left the heavy humidity, the mosquitoes, birdsongs and treefrog croakings, the proximity of friends, abandoned familiar clumpings of Karen's buckets of fossils, of sleeping, dreaming dogs, half-finished projects, pear trees just starting to bear large, sweet, juicy pears, the Crape Myrtles still gaudily pink in the outrageously green yard, simply abandoned all this, got into a bus, and headed south.
It was inevitable, but not easy, never easy to leave peacefulness and routines, friends and a welcome feeling, but it wasn't my life there in Mississippi, not my way of living to set up on a placid little porch friends had put there for me, to append myself to their lives, no matter how welcome they made me feel.
Thursday morning at dawn I found myself just south of San Antonio heading south on Greyhound, seeing outside my window low oak trees with leathery, silvery leaves, this gradually changing by noon to Mesquite, purple- flowering Cenizo, Creosote Bush and scattered cacti, drier every mile farther south I went, then the Lower Rio Grande Valley, big fields recently replanted after the hurricane. I crossed into Mexico Thursday afternoon.
What used to be, just a few years ago, vast north-Mexico Mesquite now is flat fields planted to grain sorghum, or Milo, and corn, and all afternoon I celebrated stiff wind from east off the Gulf, and I mourned the loss of what I once believed was Mesquite wilderness simply too full of life, too generous, beautiful and VAST to ever succumb, but now it was all gone, big fields, cavernous storage bins like engorged silvery caterpillars on the landscape, Garst Seed signs and pesticide and fertilizer signs along the road, but the Mesquite, gone.
All day Friday, always southward along the coast, one Gulf Coast town after another, Tampico, Veracruz, Villahermosa, passing through and out of the arid zone, by day's end Tabasco's banana plantations, sugarcane fields, flooded pastures with Zebu cattle belly deep in floodwater, grazing placidly the tops of grasses and weeds, and that green weediness explosively green, vigorous and one would think indomitable, but that's how I'd felt about the Mesquite, and I've seen the Office Depot, the Sams, the Gigante malls spreading, spreading, spreading, their vast asphalt parking lots so hot and black and lifeless that they're "glaucous," as I said of the silvery bloom on a plum a while back, "glaucous," but nothing that can be wiped away with a thumb like the glaucous bloom of a tenderly sweet, rosy plum.
Saturday morning I awoke on an ADO bus entering Mérida, the Yucatán, having all night traveled north, still following the c-shaped Mexican Gulf Coast, back north into arid scrubbiness. I'd left the Yucatán two years earlier not knowing if I'd ever return, actually preferring some new place, maybe Baja or the Copper Canyon area, but it happens that the current invitation comes from the Yucatán and so, Saturday morning, having traveled day and night since leaving Mississippi Wednesday afternoon, I stumbled from the ADO bus station and sat numbed and exhausted in San Sebastián Park next to an old cathedral, beneath spreading Ramón trees with whitewashed trunks, amazed and unnerved by how simple it can be to end one life and begin another.
SENSITIVE BRIAR IN GEORGE WEST
In south Texas the bus driver called a rest stop in the town of George West, south of San Antonio. Grass surrounding the fast-food-place parking lot was as thickly ornamented with pink globes of Sensitive Briar flower heads as a northern lawn in spring might be thick with Dandelions. You can see a couple of heads at http://www.backyardnature.net/n/08/080811mm.jpg.
Several species of Sensitive Briar exist. They're all in the genus MIMOSA. Texas seems to be home to about 17 Mimosa species and I'm not sure which one this is.
In the picture you see two globular flower heads, each composed of dozens of flowers, each flower with 4-10 stamens extending far beyond the tiny, five-lobed corollas. The flower clusters' pinkness is provided by the stamens' slender filaments. You can see that each filament is topped by a tiny, roundish anther, a pocket-like thing that slits open and releases pollen.
What's "sensitive" about the Sensitive Briar is that its leaves are touch sensitive. When I poked one with my toe, in less than a second the whole doubly- compound leaf collapsed at the petiole connection point with the stem, and the leaflets folded up.
Two dandy technical words describing touch-induced movement, by the way, are thigmonasty and seismonasty.
Some think that plant sensitivity to touch may help protect the plant from herbivores who see the collapsed leaves, think the plant may be sick, and avoid it.
MORNING GLORY TREES ABLOOM IN MÉRIDA
Sunday morning, still a bit dazed from the long trip, I walked along Mérida's famous Paseo de Montejo, a spacious, divided-lane, parklike avenue incorporating several traffic circles with monuments in their centers, and bordered with wide sidewalks with many pleasant places in which to sit. Special efforts are made to cultivate pretty plants along the avenue. A large variety of palms can be seen, bright bougainvilleas run along stone walls and art displays are set up here and there.
The most eye-catching flowering plants nowadays are the bougainvilleas, oleanders of various flower colors, and Royal Poincianas, all of which I've already introduced in these newsletters. One plant gorgeously flowering which I've not talked about, however, is an eight-ft-tall shrub branching from the base, bearing heart-shaped leaves on long petioles, and abundant cup-size, funnel-shaped, pink flowers is the Morning-Glory Tree, IPOMOEA CARNEA. The genus Ipomoea is truly the Morning-Glory genus, so this plant is a morning-glory in every respect, except that it's a woody bush, while of course morning-glories are "supposed" to be herbaceous vines, at least in the minds of temperate-zone plant lovers. You can see the Morning-Glory Tree's flowers and leaves at http://www.backyardnature.net/n/08/080811mg.jpg.
Tree Morning-Glories are native to tropical America. In our area, because of their beauty, ease of propagation and general toughness they deserve to be planted much more than they are. However, beyond tropical America the species is becoming an invasive, threatening native plants. It's prohibited in Florida and Arizona. Despite it growing here in an arid zone, in Paraguay it's regarded as an aggressive weed in wetlands and I read on the Internet that it's "found all over India."
Medicinally, its roots are boiled to use as laxative and to provoke menstruation, and the milky sap is used by traditional healers for skin diseases. However, it's dangerous when used wrong, for it's a depressant on the central nervous system, and a relaxant for muscles. It's regarded as poisonous for cattle.
WHY HERE, NOT THERE?
"Here" being the Yucatán, "there" being the US.
Nature is varied and dynamic enough in North America for me to be content forever up there as a naturalist. Also, with regard to my environmentalism, I've always felt that my fight should be in the US, not here, not only because I am native of there, but also because no civilization in the history of humanity has ever been as destructive of Nature -- with its unrestrained appetites -- as US society. I should really stay up there "thinking globally, working locally." So, why have I come here, and didn't stay there?
More than anything it's because in the US public transportation infrastructure is so poorly developed. When I'm up there in the kinds of places I like to be I'm grounded unless I hitch a ride with someone or bike, and it's simply dangerous in backcountry US to bike most roads. In Mexico, in contrast, I can get almost anywhere paying an acceptable fare. It may be in the back of a pickup truck or in a rickety micro van, but at least the option exists.
By the way, just during the few weeks I was in the US my Greyhound ticket doubled in price and service was reduced dramatically. What used to be an overnight run between Mississippi and the Mexican border, with two stopovers, now takes 22 hours with three stopovers, and each stopover is miserable. Twice in the US I had to leave the bus because I saw my baggage being removed in the wrong place, though clearly marked. In Mexico, prices haven't changed, and first-class service remains as professional as ever, which is very good.
A second reason I'm here, not there, is political. Twice last year nature-oriented organizations invited me to visit them as naturalist-in-residence and twice I was disinvited when they read my Newsletters directing readers to the Union of Concerned Scientists' documentation of how the Bush Administration consistently and destructively manipulates scientific information, and simply lies to the US public on important issues. It seems that professionally I have no future in the US. Here people are glad when I can advise them on this or that technical matter.
A third reason I am here, not there, is because at age 60 I'm anticipating needing medical services. I can't afford basic services there, but here I think I can get what I need at costs that even I can afford.
THE STORY TELLER
In recent Newsletters I've looked at the human "split brain," and neurological research conducted by Michael S. Gazzaniga.
I've thought a lot about the fact that apparently my self awareness is rooted in electrochemical reactions in a computerlike brain whose two halves project "me" as a result of their cooperation in processing information gathered through the senses. This insight introduces into my life profound mystical and magical content, for I regard it as the workings of the Sixth Miracle of Nature, defined earlier. However, this subject is so personal and abstract that I can't say much more about it.
On the other hand, one central feature of split-brain realities can indeed be spoken of. At http://www.bio.brandeis.edu/bauer/1999/gazzaniga.html we read that...
"The left brain interpreter's job is to interpret our behavior and responses, whether cognitive or emotional, to environmental challenges. The interpreter constantly establishes a running narrative of our actions, emotions, thoughts, and dreams. It is the glue that keeps our story unified and creates our sense of being a coherent, rational agent. It brings to our bag of individual instincts the illusion that we are something other than what we are."
Nothing here is said about where our self awareness comes from -- what "we" are. What the above does say is that the left hemisphere makes up stories that put our self awareness in context. It makes up stories compulsively and irrepressibly, even when the stories aren't necessarily true.
This story-making feature of the left brain suggests answers to several questions that always have mystified me.
Why do people enjoy fictional stories so much? Maybe it's because the left brain craves any story, especially a good one it doesn't have to make up itself.
Why did Germans buy into Hitler's ideas? During my several summers in Germany when I visited local libraries and talked to old Germans I decided that artful propaganda more than anything set the stage for what happened. And propaganda is just a compelling story, often repeated.
I heard an interview with Dr. Gazzaniga in which he said that if somehow all religions disappeared from Earth while everything else remained the same, humanity's left-brain compulsion to create narratives -- to come up with good stories to explain the world around us -- is so powerful that in a matter of weeks new religions would spring up everywhere.
Do other animals "feel"?
At http://www.flickr.com/photos/gaetanlee/1931470865/ you can see a chimpanzee brain clearly divided into two hemispheres. This suggests that the split brains of primates other than humans create senses of being the same way that human split brains do.
In fact, the two-hemisphered brain arose with the earliest mammals, back during dinosaur times. At first the two hemispheres provided circuitry for smelling, later for vision, and now thinking. Read about this at http://www.primatesociety.com/Into/survival/timeline/textEvol.html.
In past Newsletters I've spoken of the "snake brain" or "reptilian brain" we humans inherited from our reptilian ancestors, and which now resides at the bases of our split hemispheres. "Our reptilian brain concerns itself with circulation, respiration, digestion, elimination, mating, territorial behavior, pecking order, defense, aggression and the emotions of anger and fear," I wrote in the September 7th, 2006 Newsletter.
"Our more sophisticated, later-evolved mammalian brain," I continued, "deals with the emotions of love, sadness, jealousy, and hope, and our 'monkey brain,' crowning the other two brains, enables us to manifest the higher functions of imitation, speaking, writing, planning, symbolic reasoning and conceptualization."
Now split-brain insights add detail to how our speaking, planning, and conceptualization come about.
As such, the image of evolution propelling life inexorably toward ever more exquisite powers of discrimination, of understanding, and of imagination, becomes more vivid and powerful. More then ever we can see how Nature through evolution sought ever sharper and more capable minds. Interpreting this evolutionary history as indicating the direction of the "the Creator's Will," the spiritual imperative for sentient, thinking Life on Earth clearly reveals itself as this:
Feel more; learn more; reflect more; imagine more. Struggle to grow, mature and evolve.
Best wishes to all Newsletter subscribers,
All previous Newsletters are archived at www.backyardnature.net/n/.
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