December 2, 2012
Last week we looked at one of our LBJs, or "Little Brown Jobbies," which are brownish sparrows and other sparrow-like birds that fly up from the grass when you approach, then quickly hide someplace, often plunging back into the grass so you don't get a good look. Last week's LBJ was the Savannah Sparrow. This week I was lucky enough to photograph another LBJ, as shown at http://www.backyardnature.net/n/12/121202vp.jpg.
You might enjoy comparing that bird with last week's Savannah Sparrow, which, like this bird, also was small, mostly brown, with a notched tail and a striped chest with a dark spot in the middle, at http://www.backyardnature.net/n/b/savaspar.htm.
Like last week's LBJ, this week's was foraging in grass with its flock, which flew up as a group when I approached. However, this week's bird, instead of quickly plummeting back into the grass, flew deep inside a shadowy Ashe Juniper beside the grassy area. He must have felt secure there for he let me get close enough for our picture, and he even looked bored about it.
Judging from this week's bird's less fluttery manner of flying, this sparrow was larger than the Savannah. Savannah Sparrows are listed in my field guide as 4-3/4 inches long (12cm) while this week's species is said to be 5-1/2 inches (14cm). Also this week's bird lacked the conspicuous yellow spot between the upper beak and the eye. The most important difference, however, and one not seen in the photograph, was that when this week's birds flew away, their long tails displayed conspicuous white outer feathers.
This week's LBJ is the Vesper Sparrow, POOECETES GRAMINEUS. Like our Savannah Sparrows, it's only overwintering in our area. The bird in the picture not long ago departed its species' nesting grounds in Canada and the US northern states. The Vesper part of its name reflects the fact that often it sings at dusk, at vesper time.
PORCUPINE UP CLOSE
A month ago I got excited about seeing my first porcupine, even though the one encountered was dead along the road. This week during the dusk walk my first live one turned up sniffing and waddling along a trail beside the road, and I got a closer look. A shot of his head with its boxy snout and cauliflower ears is at http://www.backyardnature.net/n/12/121202pp.jpg.
Having a live porcupine at hand I learned that porcupines can be as oblivious to someone standing right next to them as armadillos, and they move even slower. I read that porcupines, like armadillos, have excellent senses of smell, but I didn't see any indication of this. An armadillo becoming aware that something unexpected is going on nearby rears up and sniffs, but this porcupine just looked around, showed indecision about my presence right beside him, and only slowly came to the conclusion that he ought to climb a tree. Hugging the liveoak's thick trunk with his spread front legs and with his long nails catching in the tree's rough bark, he climbed the tree very expertly. You can see him embarking on a diagonal branch at http://www.backyardnature.net/n/12/121202pq.jpg.
HARLEQUIN BUGS IN MUSTARD GREENS
In my raised beds of mustard greens, turnips, Chinese cabbage and other such Mustard-Family crops, the greatest damage has been done by Crucifer Flea Beetles, as described at http://www.backyardnature.net/n/a/fleabeet.htm.
Flea Beetles are so tiny, though, that you don't see them unless you get very close. The most conspicuous garden threat in the beds is the Spotted Cucumber Beetle, which we've considered at http://www.backyardnature.net/n/a/cuc-beet.htm.
However, the prettiest villain of the raised beds, though much less frequently seen than the flea beetles and Cucumber Beetles, is the Harlequin Bug, MURGANTIA HISTRIONICA, as shown at http://www.backyardnature.net/n/12/121202hq.jpg.
A view from the side shows that the top's ornamentation continues below at http://www.backyardnature.net/n/12/121202hr.jpg.
The Harlequin Bug's bright coloration and bold markings are warnings to birds and other predators to stay away. In Nature often it's the case that the most boldly patterned and/or colorful organisms make it easy for predators to recognize and remember them as being somehow dangerous. However, a large proportion of such attention-calling organisms are bluffing, having no significant defenses at all. That's the case with Harlequin Bugs. You can pick off as many as you want of them and thump them to your wandering hens, or feed them to your pet lizard.
Harlequin Bugs are members of the True Bug order, the Hemiptera, and the family of the stink bugs and shield bugs, the Pentatomidae. Like other True Bugs, the Harlequin bears a strawlike proboscis that can be inserted into a leaf so the plant's juices can be sucked up through it. This results in discolored blotches on the plant, and large numbers of Harlequins on a plant can even kill it.
Harlequin Bugs are native to Mexico and Central America, so in the US they are invasive, having been first detected in Texas in 1864. Now they occur throughout the US and even in parts of Canada adjacent to New England.
In early summer, in and beside wetlands, Buttonbush, CEPHALANTHUS OCCIDENTALIS, catches our eye with its spherical, white, golfball-size clusters of tightly packed flowers, as seen at http://www.backyardnature.net/n/w/buttonbu.htm.
Nowadays the flowering heads are long past, but in their stead appear fruiting heads, as shown at http://www.backyardnature.net/n/12/121202ce.jpg.
In that picture you can see that the shrub's leaves, despite our not yet having had a hard frost, are withered and falling away. Also you can see that the balls are disintegrating, usually from the top down. Probably the top parts go first because birds visit the balls and the tops are easiest to pick at. The Morton Arboretum reports over two dozen bird species that are attracted to Buttonbush.
Buttonbush's balls are composed of many crammed-together, achene-type fruits set upon their ends. Achenes are dry, one-seeded fruits that don't split open upon maturity. You can see better how they fit together to form the ball at http://www.backyardnature.net/n/12/121202cf.jpg.
Each achene is crowned by the hard, blackened calyx of the flower from which it arose. Since the calyx arises atop the fruit, not below it as is usually the case, it's apparent that the flowers forming the fruits had what botanists call inferior ovaries. Flowers with superior ovaries produce their calyx, corolla and sexual parts below their ovaries. The Buttonbush's inferior ovaries are to be expected since it's a member of the mostly tropical Coffee Family, the Rubiaceae, for which one of the main field marks is inferior ovaries.
When I first arrived here and saw that the local Buttonbushes' leaves were consistently narrower than those I'm familiar with back East, I thought we might have a different species here. However, it's the same species as in the East. Maybe the arid climate causes the narrower leaves. A second buttonbush species, the Mexican Buttonbush, does extend into the US from Mexico at the southernmost tip of Texas well south of here.
The rush of fall wildflower blossomings is over now and few flowers are to be found. However, on thin soil atop limestone rock in a semi-open spot on a hill slope there's one ankle-high herblike perennial that catches the eye not only because it's producing a pinkish flower head when everything else has passed, but also because it's so unusual looking. Its growth form is like that of a Dandelion, with deeply pinnately lobed leaves forming a ground-hugging rosette, and a single composite flower head arising on a slender, leafless stem from the rosette's center. However, the leaf margins are sharply toothed, or "spinulose-dentate," as botanists say, like a thistle's. You can see the whole thing at http://www.backyardnature.net/n/12/121202pe.jpg.
Its 5/8ths inch tall (15mm) flower head is shown at http://www.backyardnature.net/n/12/121202pf.jpg.
If you're familiar with Composite-Family flower heads, in which there are either "disk" flowers with tubular corollas (like the Eupatoriums), or "ray" flowers with longish, flat corollas (like the Dandelion), or a mixture of the two types, with disk flowers composing the "eye" and ray flowers looking like petals on a regular flower (as in the sunflowers and asters), you'll recognize that this flower head is unusual. The head's individual flowers at first look like they're all flattish ray flowers, but up close you see that they are tubular disk flowers with one side expanded into a flat, curled, tongue-like limb. They're disk flowers trying to be ray flowers.
This unusual wildflower is sometimes called Featherleaf Desertpeony or just Desert Peony. It's ACOURTIA RUNCINATA. Mainly it's a Mexican plant, found on limestone soils in much of Mexico's arid north, but it extends into the US here in Texas, in the central and southwestern regions. The genus Acourtia'a 41 known species occur only in warmer parts of North America, Mexico and Central America, and our Acourtia uncinata is the most widely distributed. I read that it's capable of flowering every month of the year, though its main blooming time is from March to August.
Desert Peopny's similarity to thistles seems to be incidental. Thistles belong to the Composite tribe Cynareae, while our Desert Peony is placed in the small, mostly tropical tribe Mutisieae. Northern gardeners might be familiar with the Gerbera Daisy, which resides in the Mutisieae.
SILVERLEAF NIGHTSHADE'S LITTLE YELLOW TOMATOES
A very common sight along weedy roadsides and in other disturbed areas is the dying-back, mostly leafless, knee-high perennial herb bearing what appear to be cherry-sized, yellow tomatoes shown at http://www.backyardnature.net/n/12/121202so.jpg.
If you know your wildflowers, even if you've never seen this species, probably you'll recognize from the tomato-like fruit that this as a member of the Nightshade Family, the Solanaceae, and the Nightshade/Tomato genus, Solanum. A closer look at a mature fruit on a branch bearing some leaves not yet fallen off can be seen at http://www.backyardnature.net/n/12/121202sn.jpg.
The fruit's structural similarity to that of a tomato can be seen in a fruit cross-section at http://www.backyardnature.net/n/12/121202sm.jpg.
The seeds are very like those of a tomato and they arise from an irregularly shaped structure in the fruit's center, the columella, very similar to the whitish, somewhat pithy center of a tomato. Tomato plants now are assigned to the nightshade genus Solanum, so these similarities are no surprise.
Our roadside plant often is called the Silverleaf Nightshade or White Horsenettle. It's SOLANUM ELAEAGNIFOLIUM. During the warm months it bears very pretty purplish blossoms with yellow centers composed of the slender, arched anthers typical of the nightshades. Though Silverleaf Nightshade occurs in so many arid, hot parts of the planet that it's hard to know for sure where its native home is, experts suppose that originally it is from northern Mexico and the US Southwest. In Australia, where it has been declared a "Weed of National Significance," it has become a serious problem in the country's wheat belt. Farmers there have reported Silverleaf Nightshade's roots penetrating the soil to sixteen feet (5m). Studies have shown that each plant is usually part of a colony with inter-connecting root systems which enable individual plants, if somehow their own roots are damaged, to keep receiving nourishment from its neighbors.
The plant's attractive little yellow tomatoes are toxic to cattle and sheep if eaten in large enough quantities, though goats seem to have fewer problems. Symptoms include profuse diarrhea. Eating the fruits regularly can cause significant weight loss and eventually death after seven to 14 days of sickness.
A grass calling attention to itself these days with its fuzzy, light-gathering, white fruiting heads atop tall, slender, stiff stems is the hip-high one shown at http://www.backyardnature.net/n/12/121202br.jpg.
At first glance it looks like foxtail grass, but up close you see that instead of the flower head being compact and spike-like, as in the foxtails, it's a narrow panicle with branches, as shown at http://www.backyardnature.net/n/12/121202bu.jpg.
A fuzz-parachuted "fruit" with its long, bent spine, or awn, is shown at http://www.backyardnature.net/n/12/121202bs.jpg.
In that picture notice the pale, slender, scoop-like item arising near the top of the caryopsis-type fruit in the lower, left corner. The scoop-like item is a sterile flower on its own stem. The ridged caryopsis in the picture's lower, left corner is disseminated on the wind attached to the sterile flower. Probably the sterile flower helps catch the wind.
Other good field marks for the species are shown at http://www.backyardnature.net/n/12/121202bt.jpg.
There at the top you see the ligule arising where the blade meets the stem. The brown item directed toward the picture's top, left is the dried-up blade, and below the ligule is the blade sheath that envelops the stem when it's not pulled away, as has been done here. Some grasses have hairy ligules, others membranous ones like cellophane, and many species have something else or no ligules at all. This grass's ligules are membranous and irregularly deeply split, and topped with a fringe of narrow teeth. In the picture's lower, left corner you see a conspicuous ring of white hairs at a stem "joint," or node. These are good field marks for the species.
This perennial clumpgrass is Silver Beardgrass, also often called Silver Bluestem. It's BOTHRIOCHLOA LAGUROIDES. The arrangement of a fertile, hairy, awned caryopsis disseminated with a smaller sterile flower is something we've seen before, among the bluestem grasses, genus Andropogon. In fact, back in my college days I learned to call this species Andropogon saccharoides, and I thought of it as a bluestem. Many pages on the Internet still list it as that.
Silver Beardgrass is abundant here, growing weedily along roads, in spots in fields of Big Bluestem, on the rocky slopes of hills, and the like. Moreover, it's a very widespread grass specializing in dry, open places from Argentina and Brazil in South America all the way north into approximately the southern third or so of the US; this is a tough, adaptable plant. Until now, despite its abundance, it's been so inconspicuous among so many more flamboyant-looking species that I've basically overlooked it. But now those slender, white heads are very eye-catching.
Silver Beardgrass is considered only of fair forage value, one grazed mainly during its early stages of development when it's most tender. Ecologically it would be seen as protecting soil in dry, maybe disturbed areas where other species wouldn't do well.
MOUGEOTIA GREEN ALGA
So far we've identified two filamentous algae species forming colorful scum atop the little Dry Frio River behind the cabin. There was Spirogyra with its individual cells occupied by beautiful chains of spiraling chloroplasts, and Zygnema, with its cells containing only two much larger chloroplasts. This week some scum turned up in a stagnate pool beside the river striking me as a little different from our previous ones. It was yellowish green and more frothy with bubbles of the oxygen it was producing as a byproduct of photosynthesis than our previous scums. Its filaments felt softer and squishier than those. You can see my fingers dipping into a blob of it at http://www.backyardnature.net/n/12/121202mi.jpg.
Under the microscope, it looked completely different from our previous algae, as shown at http://www.backyardnature.net/n/12/121202mg.jpg.
What's unusual about those longish cells is that is that they appear to be mostly empty, and the cells' contents are irregular in shape.
This time my alga-identification efforts were aided by the online key to algae at http://www.algalweb.net/search1.htm.
That key first needed to know that our alga is filamentous, which means that its longish cells are attached to one another end-to-end. Very many alga species are unicellular or colonial but not filamentous. The next feature keyed was that our filaments were non-branching. Then I had to learn what pyrenoids are to see if our alga's cells had them. It turned out that pyrenoids are organelles that fix carbon dioxide within chloroplasts, and under the microscope look like little bumps. At this point my analysis was getting shaky, but I did see bumps on what might be the chloroplast, so I said "present."
The key responded with "Mougeotia is the commonest genus answering to this description," so I looked for images of the alga Mougeotia on the Internet, found them to look more or less like ours, and after more study I grew pretty convinced that that's what we have, though I can't guess which species it is.
Mougeotia is described as a filamentous green alga whose cells contain a single ribbonlike chloroplast nestled between two large vacuoles and surrounded by a layer of cytoplasm. Vacuoles are basically storage bubbles in cells, so the "empty" spaces we're seeing at the ends of each cell are vacuoles. Cytoplasm is just the cell's gel-like substance containing the cells tiny organs, or organelles. The shriveled-looking, irregularly shaped, dark object in each cell is the "single ribbonlike chloroplast," a chloroplast being an organelle that conducts photosynthesis and other chemical reactions for the cell.
Further reading informs me that this ribbonlike chloroplast is extraordinary. It can rotate about its long axis as it orients itself perpendicularly to incoming light -- much like a mechanized solar panel!
Next I needed to put all this information into some kind of context. Was this remarkable alga common or rare? Just how unique was it?
It turns out that the previous two algae species found in the Dry Frio behind the cabin -- Spirogyra and Zygnema -- belong to the same family of filamentous, green algae, the Zygnematacae, as our Mougeotia. So, the first three algae I've identified in the Dry Frio behind the cabin are all members of the Zygnematacae.
On Wikipedia I read that the Zygnemataceae is notable among other families of alga for its diversely shaped chloroplasts, such as helical in Spirogyra, stellate in Zygnema, and flat in Mougeotia. The family is cosmopolitan, and the three genera Spirogyra, Zygnema and Mougeotia are by far its most commonly encountered genera. In one study of North American members of the Zygnemataceae it was found that 95% of the algae identified belonged to those three genera.
So, it seems that if you find a filamentous green alga forming scum, the chances are very good that your scum will be composed of one or more members of the Zygnemataceae. Also, within the Zygnemataceae the three algae genera we have identified so far in the little Dry Frio River behind the cabin are exactly the three we might have expected to find there.
FEATURED ESSAYS FROM THE PAST:
"6 Miracles of Nature," from the November 24, 2002 Newsletter, at http://www.backyardnature.net/n/p/021124.htm.
"6 Miracles, But Surer Now" from the April 6, 2009 Newsletter, at http://www.backyardnature.net/n/p/090406.htm.
Best wishes to all Newsletter readers,
All previous Newsletters are archived at http://www.backyardnature.net/n/.
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