January 5, 2014
At http://www.backyardnature.net/n/14/140105tt.jpg a Black-crested Titmouse has just flitted onto our feeder, grabbed a seed, positioned it between his feet, and now is pounding it with his beak. This feeding technique, called hold-hammering, occurs throughout the Titmouse/Chickadee Family, the Paridae. Since most other kinds of birds don't hold-hammer, a good guess is that the behavior is genetically based, and that the ancestor to all species of the Paridae passed along the gene or genes predisposing the hold-hammering technique to its descendents. We've seen the Carolina Chickadee, also a member of the Paridae, hold-hammering, shown at http://www.backyardnature.net/n/12/120422c2.jpg.
In the chickadee picture it's curious that the bird seems to be pounding the seed with his beak open. A picture of this week's titmouse with his head motion-blurred on the downswing, also with his beak open, is shown at http://www.backyardnature.net/n/14/140105tu.jpg.
If you want to see the funny look on a hardworking titmouse's face when he's staring straight at you, head-on, that picture is at http://www.backyardnature.net/n/14/140105tv.jpg.
Here in early winter I was surprised to find floating on the water's surface at the edge of the Dry Frio the freshly discarded "skin," or exuvia, of an aquatic insect nymph after it had metamorphosed into a winged adult. You can see it at http://www.backyardnature.net/n/14/140105sf.jpg.
The exuvia was only about half an inch long (13mm) so it was too have been left behind by an emerging dragonfly or mayfly. After looking around awhile a small, winged insect turned up atop a limestone cobblestone seeming to be basking in the morning sunlight, and maybe drying his wings after his recent departure from the water. He perched with his rear end curiously angled higher than his head, as shown at http://www.backyardnature.net/n/14/140105se.jpg.
It was surprising that my picture taking didn't cause the creature to fly away. Maybe he was too cold or his wings were not hardened enough after his recent metamorphosis. Whatever the cause, with such a cooperative subject I had to take a closer shot of the head, shown at http://www.backyardnature.net/n/14/140105sd.jpg.
With that thick, neck-like section behind the head, the pronotum, it looked like a dobsonfly or fish fly, but they're larger. After browsing Internet pictures searching on the keywords "freshwater insects," a match turned up. We have a stonefly, of the Order Plecoptera. If you spend much time turning over rocks in unpolluted streams you've seen lots of stonefly nymphs (technically known as "naiads"), which are easy to identify because to help them cling to their submerged rock in flowing water they are flattish. They also bear two hairlike tails, or cerci, at their rear ends. If I'd been willing to capture our subject on the rock and forcibly spread apart his wings, I'd have found that his rear end also bore two cerci.
Though I've seen thousands of stonefly nymphs I've always wondered what the adult looked like. One reason stonefly adults are less well known than their aquatic nymphs is that stonefly nymphs survive for one to four years, depending on the species -- undergoing 12 to 33 molts before emerging as terrestrial adults -- while the adults generally survive only for a few weeks, and emerge only during specific seasons. Some adults don't feed at all. Those that do feed are herbivorous.
About 28 stonefly species are listed for Texas, but identifying them to species or even genus requires more probing and dissection than I'm willing to do.
Stoneflies lack any spectacular or specialized anatomical parts. Their mouthparts are simple with chewing mandibles and their antennae are long and multiple-segmented antennae. They possess two large compound eyes and two or three ocelli, which are tiny simple eyes on the head between the compound eyes. One reason stoneflies lack special features is that they are believed to be of a primitive lineage, having close relatives identified from the Carboniferous and Lower Permian -- over 300 million years ago. In other words, their basic design was established before Nature came up with such useful concepts as the butterfly's coiled proboscis or the stag beetles oversized pincers.
Stoneflies are intolerant of water pollution, so their presence in the Dry Frio indicates that our river water is in pretty good shape.
SCARLET CLEMATIS FRUITING
Back in July we looked at our fabulous Scarlet Clematis, which in the whole world is the only clematis with truly red flowers. It's shown at http://www.backyardnature.net/n/w/clematis.htm.
Nowadays Scarlet Clematis vines bear brown, leathery leaves and fruit clusters that are nearly as attractive as the flowers, as shown at http://www.backyardnature.net/n/14/140105cl.jpg.
A close-up of the head appears at http://www.backyardnature.net/n/14/140105cm.jpg.
Thet head, which could be called an infructescence, is composed of numerous fruits, and the whole head has developed from a single flower. The flower had borne several pistils, however, and each pistil had formed a single achene-type fruit -- an achene being a dry fruit that doesn't split open when it's mature. Clematis achenes are topped with long, often curved necks called "beaks," and the beaks are very hairy, with divided hairs. Divided hairs are said to be "plumose," which means feathery. Plumose beaks help clematis fruits disseminate by wind.
At this time of year many grass species mingle in pastures and prairie patches colored pale brown-gray and dun. You'd think it would be hard to spot a rare or unusual grass species among so many frost-killed grasses, but actually each species has its own unique manner of presentation, and sometimes subtle differences jump out at you. That happened this week when amidst a lot of bluestem and grama grass a chest-tall grass caught my eye with its slender panicle whose spikelets were heavier looking and more orangish than other grasses'. You can see their flowering heads overtopping their neighbors at http://www.backyardnature.net/n/14/140105sg.jpg.
In the East the common Meadow Fescue, abundant along roadsides, produces panicles like that, but I've not seen Meadow Fescue here. A better look of the panicle's shape appears at http://www.backyardnature.net/n/14/140105sh.jpg.
Up closer still, it's clear that this was no fescue at all -- not with such long, bent, needle-like "awns" projecting from the spikelets, and all that white-hairiness on the florets -- as shown at http://www.backyardnature.net/n/14/140105si.jpg.
A look at individual spikelets shaken into my hand is at http://www.backyardnature.net/n/14/140105sj.jpg.
Something important to notice in that picture is that beside each spikelet there stands a hairy stem or pedicle. This is a feature of a certain "tribe" of the Grass Family, the Andropogoneae, so noticing this we can eliminate the vast majority of grasses, which don't belong to this tribe. Several well known grasses do, however, such as corn (maize), sugarcane, sorghum, and the bluestems. Within the tribe Andropogoneae most species bear florets atop the hairy pedicle, but this particular species does not, so that's an important field mark for this species.
Also of course when identifying a grass you need to look at the ligule, the wall-like thing -- if it exists at all -- at the blade's base where the blade meets the stem. This species' crumbling, weather-beaten ligule consists of the remains of a stiff, notched membrane, as shown at http://www.backyardnature.net/n/14/140105sk.jpg.
All these features lead us to Indian Grass, SORGHASTRUM NUTANS, which, along with Little Bluestem, Big Bluestem and Switchgrass, was a very important and conspicuous component of America's original tall-grass prairie, sometimes reaching eight feet high (2.4m). Besides in prairies, it turns up in open woods, fields and dry slopes from Quebec to Manitoba south to Florida and Arizona, and into Mexico. It can be found throughout most of Texas but I've not noticed it other than in the canyon's upper reaches, which are more part of the grassy Great Plains Province than our location down the canyon, where we're transitioning into the hot, scrubby Coastal Plain.
Besides Indian Grass's past role of contributing enormous biomass to the prairie ecosystem and thus providing grazing grass for the prairie's large mammals, it also produces edible seeds and nesting material for small mammals and birds. This is one of North America's most important natural grasses.
Arising from mud at the Dry Frio's edge were several stiff, green, knee-high stems conspicuously segmented with black and white bands, as shown at http://www.backyardnature.net/n/14/140105eq.jpg.
Up close the segment joints displayed the interesting features shown at http://www.backyardnature.net/n/14/140105er.jpg.
Anyone who has spent much time along streams recognizes this as a horsetail or scouring rush. It's a spore producing plant, whose spores escape from cones atop the stems. Our stems had lost their cones, possibly from nibbling deer.
Horsetails are very primitive plants. Earth's first flowering plants appeared about 160 million years ago but horsetails are at least twice as old, their first fossil records occurring in rocks of late Devonian age -- 340-360 million years ago. At that time land plants were just getting established, experimenting with the possibilities of having roots, stems and leaves. The dark "teeth" at the joints in the above photo are the horsetail's notion of "leaves." Horsetails are genuine "living fossils." In former times horsetails constituted a major plant group; there were forests of them. The few species we have today are just a tiny fraction of what once existed.
In our area we can look for two similar-looking horsetail species. Though if you scrape a fingernail over our plant's stem it feels like very fine sandpaper, our plant is the Smooth Horsetail, or Smooth Scouring Rush, EQUISETUM LAEVIGATUM. It occurs on riverbanks and in other moist environments all through North America and northern Mexico.
Smooth Horsetails are thought of as having stems lasting less than a year, while stems of the other species, the Rough Horsetail or Rough Scouring Rush, last for more than a year. Still, you can see that our Smooth Horsetail stems are in good shape late in the season. In fact, I find the two species hard to distinguish, at least when the cones are absent. On Smooth Horsetails cone tips are fairly rounded, while the Rough's are pointed. You see that our Smooth's joints bear one narrow, dark band. The Rough's joints often bear two, but not always.
Horsetails are sometimes called scouring rushes because their stems are coated with abrasive silicates, making the stems useful for scouring dishes.
CONTROVERSIAL WEISSIA MOSS
Atop our hill a hand-size patch of moss grows on thin soil accumulated at the base of a vertical, shadowy, well protected wall beneath a shallow overhang of hard Edwards Limestone, as shown at http://www.backyardnature.net/n/14/140105mo.jpg.
It's too arid here for most moss species to survive, and the ones who can be found seldom produce spore-producing sporangia, or capsules, which are needed for identification. However, the mosses in the picture were issuing immature sporangia, as shown at http://www.backyardnature.net/n/14/140105mp.jpg.
These are small mosses, the stalked sporangia rising only about ¼ inch high (6mm), so for identification the needed to be looked at below a microscope. The picture that made getting the name possible is at http://www.backyardnature.net/n/14/140105mq.jpg.
That image shows that the leaf has strongly incurved or inrolled margins, so the leaves are "concave," or shaped like the front of a boat or the hood worn by a monk. Such leaf tips are said to be "cucullate." This is important because some similar species produce flat leaves. Also note that the tip ends with a sharp, clear tooth, or "mucro." Leaf cells are particularly small and squarish, and each cell upper surface bears conspicuous bumps called "papillae."
Again I've been helped by a page presented by Texas A&M University at Kingsville listing findings of Dr. Cynthia Galloway's "South Texas Moss Project." There moss taxa for counties in southern Texas are listed, and that includes Uvalde County, which with 28 species has more species listed than any other county in the study area. The lists can be browsed at http://users.tamuk.edu/kfcmg00/research.htm.
On the Uvalde County list the three species at the bottom -- Tortella flavovirens, Tortella humilis and Weissia controversa -- all are strikingly similar to one another and look like our moss. However, the Flora of North America says that "... all specimens named Tortella flavovirens that were collected inland from coastal habitats were redetermined to be some other species..." On the basis of that statement, since we're inland, I'm discounting T. flavovirens. The leaf tips of T. humilis are described as not being shaped like a monk's hood, or cucullate, so I'm discounting that one.
That leaves, sometimes called the Controversial Weissia, WEISSIA CONTROVERSA, its common name based on the binomial, which reflects the confusion and disagreement among early bryologists about the species' validity as a species. The Controversial Weissia occurs worldwide and adapts to a remarkable range of habitats -- from "Weedy, soil, rock, disturbed areas, roadsides, fields, acid or calcareous substrates," according to the Flora of North America.
A HALF-OPEN TEXAS STAR
Last month we looked at some unopened Texas Star mushrooms, which looked like dark acorns sitting on their cups, on the ground, shown at http://www.backyardnature.net/n/x/tex-star.htm.
Those unopened Texas Stars never did develop into the widely spreading "stars" that make them so spectacular at certain times of the year. Ours partially opened but then dried up and turned into a contorted, black mess. Now another one that wasn't apparent earlier, apparently because it formed deeper in the soil, is partially open, as shown at http://www.backyardnature.net/n/14/140105st.jpg.
I'm watching it, hoping it'll develop, but it's set so deeply in the soil I wonder if it can ever fully expand.
Continuing the project of learning to associate the appearance of algae in the Dry Frio River with how they look under the microscope, I chose a dead, decaying, submerged stem of a Water Willow extending a few inches up from the river's floor and covered with a yellowish-green fuzz, which I assumed to be algae. You can see the submerged stem with its covering of hairlike, 1cm long (3/8ths inch) filaments at http://www.backyardnature.net/n/14/140105cy.jpg.
As soon as some filaments were seen under the microscope it was clear that we didn't have an alga at all. No cell wells were to be seen, as well as no photosynthesizing chloroplasts or any of the smaller organelles to be expected in an alga cell. You can see what appeared at http://www.backyardnature.net/n/14/140105cv.jpg.
The regularly spaced partition-like features within the filaments don't extend all the way to the filaments' sides the way they would if they were cell walls. Also, note the pale glow along the filaments' sides. That's light refracting through a thin, gelatinous covering of the filaments. Other filaments in the sample were at different stages of development, as seen at http://www.backyardnature.net/n/14/140105cw.jpg.
At the picture's top, left, there appears to be a kind of casing composed of the gelatinous covering from which the contents have escaped. Scanning more filaments, more states of development turned up, including the one filled with tiny, granular items shown at http://www.backyardnature.net/n/14/140105cx.jpg.
In November of 2012 while looking at patches of scum forming atop the Dry Frio we identified the scum-forming organism as a cyanobacterium, probably the genus Oscillatoria. That page is at http://www.backyardnature.net/n/x/scum.htm.
From what we learned then, we can suppose that once again we have a cyanobacterium, not an alga, but maybe this is a different one. One reason it might be different is that the gelatinous covering -- or "sheath," when speaking of cyanobacteria -- appears to be very thin or missing in Oscillatoria. Cyanobacteria are turning out to be much more interesting and commonly occurring than I'd thought. You might like to check out their Wikipedia page at http://en.wikipedia.org/wiki/Cyanobacteria.
One of the most mind-boggling facts about cyanobacteria is that early in the history of Life on Earth they consumed so much of the carbon dioxide in the atmosphere, through photosynthesis, and produced so much oxygen that they made life possible for us animals. A graph showing the change in the atmosphere's gas composition is at http://ircamera.as.arizona.edu/NatSci102/NatSci/text/atmosgases.jpg.
Cyanobacteria used to be called blue-green algae. Now most experts regard them as bacteria, but in truth they don't fit either category. Cyanobacteria don't have cell nuclei containing genetic material as do the algae, yet they photosynthesize, which bacteria in general don't do.
I'm not sure which cyanobacteria species this is. Browsing the Internet I get the impression that three important freshwater, filamentous genera to look for are Oscillatoria, Phormidium and Lyngbya. At one site I read that "Lyngbya is very similar to Phormidium, which has a looser sheath, and to Oscillatoria, which normally lacks a sheath." Some of our filaments seem to have pretty loose sheaths so that's a vote for Lyngbya, but some pictures of Phormidium on the Internet are somewhat similar to ours. That's as far as I can get with it.
Whatever the name of our twig's cyanobacterium, I'm eternally grateful for the enormous quantities of oxygen cyanobacteria have produced throughout the eons.
At http://www.backyardnature.net/n/14/140105fr.jpg you can see how a stretch of our little Dry Frio River looks in winter. The leafless trees are sycamores. On the hill the green trees are Texas Liveoaks and Ashe Junipers, and the rusty colored ones are Texas Red Oaks. The tall tufts of orangish grass along the river are Bushy Bluestem and the slender stems poking up from the water are frost-killed remains of Water-willow.
The muted colors are pleasing to look at, somehow feeling just right for this time and place, and perfectly complementing a cold morning's sounds: hoarse croaks of Ravens calling from the hills; rocks knocked loose by nearby foraging bands of deer and feral pigs; water trickling over a little dam created by a fallen tree.
Now at last the days grow longer and already spring is in the air. At the Bushy Bluestems' bases green shoots are emerging, and here and there open ground is carpeted green with tiny, ground-hugging, freshly sprouted winter annuals. On sunny mornings sometimes birds briefly break into spring songs, just halfhearted snippets of what's to come, but they're spring songs nonetheless, and when you walk, sometimes you pass through currents of warm, moist air that affect you softly, like remembering a long-past romance. In fact, one yearns for more sunlight and warmth, and for more songs and blossoms, and the grand orchestration of photosynthesizing life with animals being hungry and horny and just plain happy.
These signs of spring are happening exactly when and where they should, happening like clockwork, and standing looking at the scene I think how often in my life I've let the whole spring-coming process draw me into it, wash over me, and I remember how good it felt.
But, also standing there I notice that the river is much lower than this time last year. We're in a multi-year drought here and I wonder to what extent the drought relates to the general consensus among climatologists that with global warming this part of the world will become drier, and the Chihuahuan Desert to our west will be expanding in our direction. Even if we'd get greenhouse-gas emissions under control today, they say, global warming will continue; and levels of those gases actually are increasing at a faster rate than at any time in hundreds of thousands of years.
Shaking these thoughts from my head, I focus on the fact that the landscape before me displays itself as a mosaic of patch-like communities. A riparian ecosystem with its sycamores and Bush Bluestem extends along the river, prairie grass dominates the open, cobblestone-floor floodplain, and junipers and oaks populate the slopes beyond, trees thinning and diminishing in size higher up until low scrub dominates the crest. In Nature, at every level, mosaics are more stable and sustainable than monocultures.
So, if you believe as I do that humans are part of Nature and that our societies ultimately must adhere to natural laws or else disappear, then you have to think that the monoculture-like, materialistic, consumption-oriented, greenhouse-gas spewing manner of being that has spread across the planet now similarly must fracture -- in fact is fracturing at an accelerating rate, fracturing into haves and have-nots, into mutually antagonistic religions, red states and blue states, blighted cities with islands of gentrification, vast corporate farms intermingled with organic orchards and back-to-earth communities, on and on, so in this mosaic there are patches with patches, some patches " healthily sustainable," some "destructively unsustainable," and one struggles to find the patch to identify with...
Spring is coming, the river is low, and what touches me most is the ravens' lusty but solitary croak echoing off the canyon's walls.
FEATURED ESSAYS FROM THE PAST:
"The Sky is Blue" from the December 22, 2002 Newsletter, at http://www.backyardnature.net/n/p/021222.htm.
"Into a Bubble of Calmness" from the March 23, 2009 Newsletter, at http://www.backyardnature.net/n/p/090323.htm.
Best wishes to all Newsletter readers,
All previous Newsletters are archived at http://www.friocanyonnature.com/n/.