JIM CONRAD'S
NATURALIST NEWSLETTER
Issued from the valley of the Dry Frio River on the
southern slope of the Edwards Plateau, northern
Uvalde County, southwestern Texas, USA

December 29, 2013

LAST DRAGONFLY OF THE YEAR
On flat, unvegetated, Edwards Limestone bedrock capping the very top of our hill, on Solstice Day I was surprised when a red dragonfly landed right beside me. The surprise was not only because it was so late in the year and after several hard freezes, but also because we were about half a mile (0.8km) from the Dry Frio's nearest standing water. You can see the critter at http://www.backyardnature.net/n/13/131229df.jpg.

Earlier this month we profiled the Variegated Meadowhawk Dragonfly, similarly red, and described in Dunkle's Dragonflies through Binoculars as "... the dragonfly most likely to be seen in the desert miles from water." Surely this was the same species. The Variegated Meadowhawk is shown at http://www.backyardnature.net/n/a/meadhawk.htm.

However, there you can see that that species displays a distinct "red-skeleton" ornamentation on its slender rear end, which our hilltop one lacks, plus the bases of the four wings of that one aren't flushed with amber like this one's. This must be a new species!

The hilltop species looked enough like the previous meadowhawk for me to go directly to the dragonfly book's meadowhawk page, where the new species was pictured just below the previous one. It's the Yellow-legged Meadowhawk, SYMPETRUM VICINUM, in the same genus as the Variegated species. And once the Yellow-legged name brought my attention to the matter, in fact the Yellow-legged does have yellow legs, which look even more brightly yellow than they are when viewed from above through the dragonfly's amber wing bases. The Variegated Meadowhawk's legs are black with yellow stripes.

Once again Dunkle's description of the species' hits the spot exactly, when he writes that "... it may not begin breeding until late Aug., and is often the last dragonfly seen each year."

More and more it's becoming clear that the various dragonfly species are much more distinctive than I ever thought possible, and each species seems to have its own personality. For example, Dunkle says of the Yellow-legged Meadowhawk that "At low temperatures they perch on the ground, switching to leaves, and then to stems as the temperature increases. Pairs often form tandems away from water, then fly to water where they make false egg-laying movements before mating and commencing real egg laying."

Yellow-legged Meadowhawks are widely and curiously distributed in North America, from southeastern Canada to northern Florida west to New Mexico and North Dakota, with a thin isthmus of population extending westward, where they spread from northern California to southern British Columbia.

*****

LITTLE WATER STRIDER
After several hard freezes I wasn't expecting to find much animal life around the little pool attached to a stretch of the intermittent Dry Frio's running water. However, something small enough that I couldn't quite make it out with my foggy vision was skating across the water's surface, so I set the camera on automatic, held it above the critter, and got what's shown at http://www.backyardnature.net/n/13/131229ws.jpg.

It's two critters instead of one and though they don't seem to be mating, at least the one on top appears to be enjoying a free ride. They're water striders, but not the regular, much larger species. You can judge how tiny they are by the featherlike Baldcypress leaf beneath them.

Anatomically they are similar enough to the larger Common Water Strider, genus Gerris, to guess that they're in the same family. However, their body sections are different enough from Common Water Striders that probably they belong to a separate genus. Thinking like that as I browsed around, finally it became clear that we have NEOGERRIS HESIONE, and though it's found from New York Michigan and Nebraska south to Florida and Texas, as well as in Cuba and Central America, it bears no common name I can find. That's a shame, so here we'll name it the Little Water Strider.

In fact, compared to other water strider species, Neogerris hesione has very little information published about its life history. One feature that is known, however, is that individuals come in both wingless, or "apterous," and winged, or "macropterous," editions. Ours are wingless. This fits in with a 1958 study by C.A. Wilson reporting that 95% of adults in Mississippi were apterous, or wingless.

It's known that couples of Little Water Striders may travel as shown in the picture, together but not mating, both before and after mating, and they do this for some days.

I think we're making a small contribution here by documenting the fact that in our part of the world Neogerris hesione couples may be observed skating together in late December -- December 22, to be exact.

*****

BASKING FOX SQUIRRELS
On recent chilly but sunny mornings two or three Fox Squirrels usually could be seen basking in the sun, their bodies perpendicular to the incoming rays and their luxuriously fuzzy tails deployed over the side of a liveoak's leaning trunk. You can see a pair hard at it at http://www.backyardnature.net/n/13/131229s2.jpg.

*****

LAST NEW WILDFLOWER OF THE YEAR
Despite several recent hard freezes, here and there you can still find wildflowers blooming, moistly commonly occurring members of the Composite or Daisy Family. However, I look for species I've not noticed before, and this week I felt sure there'd be none of those. However, a new one did show up, a small, very modest looking, scraggly herb with most of its stem leaves fallen off, growing in an especially well sheltered spot between limestone rocks on the south face of our hill, shown at http://www.backyardnature.net/n/13/131229eu.jpg.

With those opposite leaves -- two leaves per stem node -- and the leaves' shape and the way they tend to cluster at stem tips, already many folks will recognize this as a kind of euphorbia, also called spurge or sandmat. Very many euphorbia species exist, but all share an unusual and distinctive flower anatomy. Just to make sure it was a euphorbia I looked for a blossom, which was hard to find because it was so small. You can see it at http://www.backyardnature.net/n/13/131229et.jpg.

The three-cornered, reddish item in the middle of the picture is the ovary and future capsule-type fruit. It's on a short stalk arising from a cuplike structure known as the cyathium, and inside the cyathium reside maybe four male flowers. In other words, among the euphorbias there are separate male and female flowers, but the various flowers are arranged into a blossom-like head with tiny, much-reduced male flowers inside the head, or cyathium, and with the single female flower banished outside. That weird anatomy is shared by all euphorbias.

Plants known as euphorbias mostly belong to the genus Euphorbia, but during recent years most taxonomists have separated out a certain group of those -- species with leaf bases bulging downward on one side of the leaf midrib but remaining narrow on the other side -- into the genus Chamaesyce. Species remaining in the genus Euphorbia bear symmetrical leaves whose sides mirror one another. You'll notice that our plant's leaves bulge downward on one side of the midrib, so this is a member of the genus Chamaesyce, though commonly it's also referred to as a euphorbia.

It's the Hairy Euphorbia, CHAMAESYCE VILLIFERA, and besides its small size -- its leaves are only about 3/8ths inch long (1cm) -- and the leaves' short, broad shape, and the stems' reddness, the main field mark for this species is its sparse covering of fairly long, soft hairs, as shown at http://www.backyardnature.net/n/13/131229ev.jpg.

Many euphorbia species are weedy and widely distributed, but some are true wildflowers, and some are even rare. That's the case with the Hairy Euphorbia, which is endemic only to the southern border of the Edwards Plateau in Texas and in arid northern Mexico.

The Hairy Euphorbia's vegetative parts issue white, milky juice when damaged, but that's typical of the euphorbias. In general, euphoriba latex contains powerful and sometimes toxic chemicals, but this species is so small and spindly that that's of little consideration here. One can imagine small sparrows gladly pecking at its fruits.

*****

CONCRETE MOSS
Mosses occur much more frequently in moist environments than dry ones, and it's true that in our arid landscape you seldom see them. Mainly they appear in small patches on ground next to the Dry Frio River, on shaded arroyo banks -- arroyos being streams that flow only during infrequent rains -- and spots beneath power lines that for some reason grass hasn't invaded. All these environments appear to be populated by the same moss species, which I haven't identified because of lack of sporangia, which are the structures in which spores develop. Among mosses, sporangia are as distinctive and necessary for identification as are flowers when naming flowering plants.

This week a cutting-board-size patch of mosses very different from the usual ones turned up on a flat, nearly bare, horizontal layer of hard Edwards Limestone capping our hill. As mosses go, it was a large species, as you can see by scaling it against the fallen leaves, at http://www.backyardnature.net/n/13/131229mo.jpg.

At first I had no hope for identifying the plants because no sporangia were apparent. Even with sporangia, identification is a challenge because about 12,000 moss species are currently recognized. Since mosses reproduce with spores, and spores can be disseminated by the wind, many of those species conceivably could turn up here.

Still, this was the only population of this species I'd seen and its identity could be important. On hands and knees I combed the whole little colony for at least one sporangium or the remains thereof, and I was awarded with what's shown at http://www.backyardnature.net/n/13/131229mp.jpg.

Here we have only the remains of a sporangium, which earlier was a baglike capsule perched atop a purple stalk. Now only a shattered, goblet-shaped husk remains, but what's shown helps a lot. The picture shows that the stalk arises not at the stem's tip, as it does on many mosses, but rather along a branching stem. Many moss stems don't branch at all. The sporangium seems to have been longish instead of spherical, and more or less symmetrical, while many species produce distinctly bent, asymmetrical ones. Also very important for identification purposes was that the stem grew horizontally on the limestone surface, with only branch tips directed skyward. Many moss stems strictly grow vertically.

From past experience I knew that even seeing such important field marks, probably I'd need a microscopic look at the leaves, so I plucked a leaf and later got to see the 3.5mm-long (±1/8th-inch) leaf shown at http://www.backyardnature.net/n/13/131229mr.jpg.

As moss leaves go, this 3.5mm-long one is pretty large. Also, few kinds of moss produce leaves with such distinctly spiny margins. Most moss leaf margins bear no spines or teeth at all. This leaf clearly has a midrib, or "costa," while many moss leaves don't. Even higher magnification reveals more important details, at http://www.backyardnature.net/n/13/131229mq.jpg.

There it's shown that cells along the margins' borders are similar to those in the rest of the leaf -- all short, squarish ones -- which is noteworthy because in some species cells along the margin are much elongated. In some species all the cells are longish, and display thinner cell walls. Sometimes cell walls are irregular, as if they'd been jig-sawed, but these are regularly short-rectangular.

Even noting all these details I had no success with the Flora of North America's very technical keys, especially because of the lack of a complete sporangium. However, I had the good luck to find on the Internet 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.

So, by comparing our pictures with each of the 28 species in Dr. Galloway's list, by far the best-matching species is PTYCHOMITRIUM SERRATUM, not really known by a common name, though some publications make up the name "Serrate Ptychomitrium Moss," based on the Latin. I think of it as the Concrete Moss, and here's why:

The Flora of North America says that the species occurs in Mexico and the Dominican Republic, and in the US in Texas, Louisiana and South Carolina. A recent paper includes findings in Tennessee, New York and Massachusetts. Normally the species occupies calcareous rock such as limestone, but in sites from Eastern Texas eastward and to the north, most finds have been on concrete -- which basically is manmade, calcareous (calcium-rich) rock. The species appears to be expanding its distribution, then, by accepting its calcium from manmade sources. One author proposes that the range expansion toward the northeast follows prevailing "storm tracks"; winds blow spores from here to concrete areas downwind.

*****

BIG BLOBS OF ALGA
Under the microscope we've identified several species of algae found in the Dry Frio but now I'm realizing that even if I can recognize them under the microscope, I can't in real life. Now I'm going back and relating the names to how they look in the field.

One alga species catching the eye nowadays forms bushel-basket-size-and-larger, emerald-green blobs in the Dry Frio's deeper water -- knee deep or so. Over time the blobs expand and when they reach the water's surface their exposed parts form a yellowish-green scum. At first glance you don't even notice that the pretty-looking, billowy submerged blobs produce the scum. You can see how all this looks at http://www.backyardnature.net/n/13/131229al.jpg.

By noticing the floating sycamore leaf at the picture's lower, left you can gain an idea of how large the submerged green blobs are.

A smidgeon of a blob brought to Juniper House and placed below the microscope's lens revealed the filaments appearing at http://www.backyardnature.net/n/13/131229am.jpg.

We've seen that very thing, calling it Mougeotia. You can see our Mougeotia page at http://www.backyardnature.net/n/x/mougeoti.htm.

So, now we know that Mougeotia makes those marvelous big blobs that look like they're bubbling up from the river's floor. Physiologically, Mougeotia species are famous for their cells' flat, ribbonlike chloroplasts, which orient themselves relative to the light. In the last picture the irregular-shaped objects in each cell are the chloroplasts twisting this way and that.

Another odd feature of Mougeotia filaments is that they "genuflect" -- a straight filament will abruptly bend sharply and grow off at an angle. A genuflecting filament is seen in the center of the above picture.

Mougeotia, like similar filamentous algae, provide shelter and food for many kinds of small invertebrate and vertebrate aquatic animals, and of course they photosynthesize good old free oxygen for a world intent on burning it as rapidly as possible.

*****

TEACHINGS OF A SPARROW AT THE FEEDER
After a satisfying meal of greens and cornbread, midday sunlight warmed and mellowed so agreeably that I just let my back slide down the birdfeeder's post being leaned against, and I lay on the deck's floor with closed eyes. Nice breeze, Wild Turkeys scratching beneath the junipers a few feet away softly clucking to one another, and I drifted toward a snooze.

But then birdseed peppered my face. Above, a Chipping Sparrow would grab a seed, peek over the birdfeeder's edge to see what I was doing, and repeat the operation again and again. He was super vigilant, but taking care of business.

The feeder has been up for a month or so, but still very few birds visit it. In town, flocks mob well supplied feeders and if food disappears from one feeder the birds simply shift elsewhere. But here there's no other feeder within range. These woods birds aren't used to being coddled, and they keep their guard up. Out here, basic rules for survival -- basic laws of Nature -- are still respected.

Under the influence of warm-sunlight drowse, thoughts wander in unexpected ways. At first there's simple admiration for how alert and fine-tuned to his world this little being above me is. That thought morphs into a reflection that maybe the Chipping Sparrow has a message for anyone willing to accept it.

For example, after a minute or two, without staying and gorging as a city bird might, the Chipping Sparrow flies away. In doing so he keeps his food sources diversified. Our society, in contrast, offers most of us just one option for our food, that of buying it commercially. Yet the infrastructure supporting that system is unsustainable, not only because it depends on such shaky things as currency stability and availability, a functioning Internet, and untold numbers of bridges and tunnels, but also because it requires economic "growth" to maintain it -- on a planet staying the same size, and where resources are only diminishing.

The beauty of the bird feeding above also reminds us that adorning our lives with the motifs of sustainability, such as well maintained gardens, orchards and greenhouses, enriches our lives, the produce itself being a delight to behold, to smell and taste. And that's just the beginning, for kitchens redolent with odors of herbs, baking bread, pungent garlic, and bubbling pots of beans not only nurture strong, healthy bodies seldom in need of the medical industry, but also happiness. Ordering and simplifying life so that there's enough time for idle thinking, for art, and for just looking around, enables us to enlarge ourselves as human beings.

Here at the beginning of the New Year when one welcomes ideas for rethinking and reinventing ourselves, the Chipping Sparrow suggests good ideas as he flits into pure air and sunlight, like a thought on its way to becoming a prayer of thanks.

*****

FEATURED ESSAYS FROM THE PAST:

"Evolving, Coalescing Social Consciousness" from the May 30, 2004 Newsletter, at http://www.backyardnature.net/n/p/040530.htm

"Gardeners Are Nice People" from the December 29, 2002 Newsletter, at http://www.backyardnature.net/n/p/021229.htm

*****

Best wishes to all Newsletter readers,

Jim

All previous Newsletters are archived at http://www.friocanyonnature.com/n/.