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

November 25, 2012

SAVANNAH SPARROWS
In the dun-colored ocean of foot-high Big Bluestem grass blanketing the floodplain of the Dry Frio River there are lots of quick, little, brown birds who fly up like scared grasshoppers when you approach, then just as fast drop back into the grass a bit farther away. But one day this week, instead of immediately plummeting back into the grass, one flew into a nearby Mesquite tree and perched long enough to have his picture taken, as shown at http://www.backyardnature.net/n/12/121125ss.jpg.

He's a Savannah Sparrow, overwintering in this part of the world after recently migrating from the species' nesting grounds in Canada and the northern US. The species also is a permanent resident on the West Coast but, this far east, the one in the picture certainly has flown from far to our north.

At first glance, seeing the big central spot on his chest, I thought he was a Song Sparrow. But then I noticed the flush of yellow between the eye and upper part of the beak -- the "yellow lores" -- and along with the deeply notched tail, that made him a Savannah. Interestingly, my dog-eared 1966 Robbins Birds of North America field guide specifically states that Savannah Sparrows bear no central spots on their breasts, but other works say that usually they do.

I suspect that other species of quick, little, brown sparrows are out in the grasslands so I intend to keep photographing whatever pops up. Already, just knowing that we have Savannah Sparrows here somehow makes the grass ocean around me feel even more congenial than it already does.

*****

APHIDS ON CUCUMBER VINES
Before this year I've not gardened in southwestern Texas so really I'm not sure what should and shouldn't be planted for the winter garden. When I started planting in August I was fairly sure that plants like tomatoes and cucumbers wouldn't make it, but in October tomato sets went on sale at a local store, we got some, and now in late November we're having ripe tomatoes from the vine. Just for the fun, we also planted a few cucumber seeds, and now those vines are flowering.

The other day the cucumber vines' fuzzy, rapidly growing stem tips acquired a certain silvery, flaky messiness, as you can see at http://www.backyardnature.net/n/12/121125aq.jpg.

Any gardener recognizes that here the stem tip is covered with the discarded exoskeletons of aphids. As insects grow, periodically they split from their exterior skeletons, or exoskeletons, abruptly expand in size, and once their new exoskeletons have hardened enough they move on, abandoning their old exoskeletons in places like our cucumber vines' stem tips.

It was easy to find living aphids busily sucking juices from the cucumber vines' leaf undersurfaces. I tore off a leaf and looked at my unwelcome guests below the dissecting scope. You can see a couple at http://www.backyardnature.net/n/12/121125ap.jpg.

Best I can determine, these are Melon Aphids, sometimes called Cotton Aphids, APHIS GOSSYPII, in which larger, dark-green individuals such as the one in the photo habitually occur, and for which cucumber vines are listed as important foods. Many species of aphids are known, and mostly they infest just one or a few kinds of plants.

I couldn't find winged individuals on these vines, and that might be because we're so far south. In the north -- north of Arkansas, approximately -- female Melon Aphids typically hatch in the spring from eggs on the primary plant host. They feed, mature, and reproduce asexually, or parthenogenetically, on this host all summer, or else they might produce winged females who fly off to a secondary host to form new colonies, where both winged and wingless female offspring are produced. Under warm conditions, a generation can be completed parthenogenetically in about a week. Late in the season, winged females return to the primary host, and then as the season ends both males and egg-laying females are produced. They mate and females deposit eggs that overwinter.

Here farther south, sexual forms may not form at all during the year. Females continue producing offspring without mating for as long as weather allows feeding and growth. Among the many aphid species, one feature distinguishing Melon Aphids is that hot weather doesn't bother them.

So, maybe I'm not seeing winged individuals because our Melon Aphids are just producing one quick generation after another of wingless females. No males are needed for this simple strategy, and where crops are produced year round in one place, no wings, either.

*****

HOPTREE FRUITING
A certain crooked-stemmed shrub or small tree sprouting interwoven branches grows in the shadowy understory of the forest on the alluvial terrace alongside the little Dry Frio River. It's completely winter-leafless now and would be hard to identify, but for its very distinctive fruits, a cluster of which is shown at http://www.backyardnature.net/n/12/121125pt.jpg.

Those fruits, each with a seed suspended in its center surrounded by a network of lacy veins, are pretty to look at when bright light is behind them, as seen at http://www.backyardnature.net/n/12/121125pu.jpg.

Once you've met these very unusual fruits you're not likely to forget the tree producing them. It's the Hoptree, sometimes called Wafer Ash or Stinking Ash. It's PTELEA TRIFOLIATA, a member of the Citrus Family, the Rutaceae. They say that no other member of the Citrus Family lives in the wild farther north than the Hoptree. Of course the Citrus Family is the one bringing us oranges, lemons, limes, grapefruits and the like.

In Mexico we've seen that the leaves of Citrus Family members typically are spicy-pungent, bearing many embedded glands filled with aromatic oils. The Hoptree's leaves similarly are odoriferous, maybe with a hint of lemon fragrance, but mainly the smell is so musky that you understand why some people call it Stinking Ash. The "ash" part of the name is because Hoptree's leaves are trifoliately compound, as ash tree leaves are compound, but beyond that they don't have much in common.

Hoptrees display a spotty and curious distribution pattern in North America and Mexico. They're found in a band from south-central Mexico all the way through here to southern Michigan. They occur only in small parts of Kentucky and Mississippi, though they're found in nearly all of Georgia and North Carolina, and in many isolated populations in Arizona and New Mexico, and other states as well.

Smelly plants typically have a history of being used as traditional medicines, and Hoptrees fit that stereotype. Most of the old herbals say that infusions made from its roots help the lungs recover from chest inflammations, and to serve as a general tonic.

*****

RABBIT-TOBACCO
Back when the Rabbit-Tobacco along our dusk-walking road was flowering I didn't pay much attention to it because so many more interesting and eye-catching plants were blossoming at the same time. Rabbit-Tobacco, after all, is basically a weed found throughout eastern North America and its flowers are tiny, pale things. However, now that the fall wildflowers have mostly faded here, turning brown and brittle, and falling to the ground despite our have had no frost, and because this week I've had a chest cold, suddenly the Rabbit-Tobacco along the road took on a new interest.

First, our Rabbit-Tobacco -- sometimes called Cudweed, Sweet Everlasting, and other names -- is PSEUDOGNAPHALIUM OBTUSIFOLIUM, a member of the Composite or Sunflower Family. You can see what it looks like nowadays at http://www.backyardnature.net/n/12/121125gn.jpg.

Note that the plants' leaves are dry and curled up, and that what could be bunches of white flowers actually are clusters of composite-flower heads long past their flowering and fruiting seasons. The plants' white "heads" whitish, chaffy involucres empty of their contents. You can see a close-up of some heads on conspicuously white-hairy stem branches at http://www.backyardnature.net/n/12/121125gp.jpg.

A little to the left and below the center of that picture you can see a parachuted, cypsela-type fruit suspended between two inflorescence branches, looking like a tiny milkweed seed.

Also you can see that the plant's white hairiness continues onto the lower stem and covers leaf undersides at http://www.backyardnature.net/n/12/121125go.jpg.

Now to the matter of my having had a chest cold this week. I can't see Rabbit-Tobacco without remembering my experiences among the Tzotzil-speaking indigenous folks of upland Chiapas, southern Mexico. Traditionally a member of this group of plants, maybe even the very same species, has been used medicinally to cure respiratory ailments. Down there it's called Gordolobo, or "Fat Wolf," and in the highlands where chest colds are common and the plant grows profusely in pastures and along roads, Gordolobo is a very important medicinal herb.

So, this week on one of our evening walks I broke off a good-sized sprig of Rabbit-Tobacco and the next morning put the whole thing into a saucepan of boiling water. The water very quickly turned yellow, and then dark amber. I remember the teas made in Chiapas as being bright yellow, so I figured I'd used too much Rabbit-Tobacco, and diluted it until it was the right hue of yellow. Then I drank it.

Maybe my chest cold was due to break up anyway, but the fact is that within an hour my sinuses had unclogged for the first time in days and my chest didn't feel nearly as congested as it had earlier. You just never know how much you're imagining these things, and how much a medicine is genuinely helping you, but it sure seemed like to me that drinking two quarts (liters) of Rabbit-Tobacco tea helped alleviate my cold symptoms.

In fact, ethnologists have documented the use of Rabbit Tobacco for treating asthma among the Rappahannock, Eastern Cherokee and other Native American groups. In their field guide to medicinal plants in eastern and central North America, Steven Foster and James Duke identify Rabbit Tobacco as a remedy for sore throats, pneumonia, colds, fevers, upset stomach, abdominal cramps, asthma, flu, coughs, rheumatism, leukorrhea, bowel disorders, mouth ulcers, hemorrhage, tumors, and say that it has been used as a mild nerve sedative, a diuretic, and an antispasmodic.

And it can be smoked as a tobacco substitute.

*****

SWITCHGRASS
In earlier Newsletters featuring our local grasses we've referred to the convention that often when referring to the grass species constituting central North America's vast prairie region, we speak of the "Big Four" species -- Big and Little Bluestems, Indiangrass and Switchgrass. In the valley of the little Dry Frio River Little and Big Bluestems are abundant. The other two species are present, but not nearly so common.

Switchgrass, PANICUM VIRGATUM, is a perennial clumpgrass like the other "Big Four." It grows commonly along the moist banks of the Dry Frio, and on fields of cobblestones in the river's floodplain not high above the river's level, but I don't find it in drier environments elsewhere. Along the river it's a tall grass, its flowering heads rising well over seven feet (2.1m), as shown at http://www.backyardnature.net/n/12/121125pa.jpg.

Switchgrass's flowering heads, or inflorescences, are large and disperse panicles with small spikelets at branch tips, as shown at http://www.backyardnature.net/n/12/121125pb.jpg.

The spikelets are only about 3/16ths inch long (4.5mm) and each spikelet produces only one grain. Three spikelets are shown at http://www.backyardnature.net/n/12/121125pc.jpg.

One final field mark is that the ligule -- the eyebrow-like growth where the blade base meets the stem -- consists of a dense tuft of hairs, as shown at http://www.backyardnature.net/n/12/121125pd.jpg.

Some grasses have cellophane-like ligules, others have lobed or pointed ones, some grasses have none at all.

Switchgrass occurs naturally from Canada through the US, deep into Mexico. If you've been paying attention to news in the field of alternative energy sources, you've heard a lot about Switchgrass, because it's been singled out for its potential as a very significant source of bioenergy. It produces a lot of stems and leaves relatively quickly, without needing much fertilizer or pesticides, and those stems and leaves can be fermented to produce ethanol. Switchgrass stems and leaves also can be formed into hard pellets which can be burned directly in stoves, instead of coal or wood. Under the heading "Bioenergy," the Wikipedia Switchgrass page does a good job summing up the present state of using Switchgrass as bioenergy at http://en.wikipedia.org/wiki/Panicum_virgatum.

Switchgrass has its own website at http://www.switchgrass.nl/.

One problem with using Switchgrass for bioenergy production is precisely the fact that it's a crop that can be grown on what's usually called "marginal land." "Marginal land" is land usually not yet taken over by agricultural monocultures such as cornfields and wheatfields. Monocultures are ecological deserts, are murderous to wildlife, and represent the opposite of biodiversity.

But already the world has focused enough on Switchgrass's potentials for several cultivars to have been created, which produce more energy with less fertilizer than the wild stock. In the US, Switchgrass genes have been modified so that plants produce polyhydroxybutyrate, which is a polymer belonging to the polyester class. Polyhydroxybutyrate accumulates in beadlike granules within the plant's cells. One use for it might be the making of polyester-type clothing.

*****

CHICKEN OF THE WOODS MUSHROOM
In this arid region much fewer mushrooms are apparent than farther east. However, we do have some, and this week a certain one has put on a show emerging from a wounded Texas Live Oak along the river. It was a shelf fungus, a stalkless one growing like a fan stuck into the side of the tree, about the size of my hand with fingers spread, and bright yellow-orange. You can see it emerging from the cambium area of a circular wound where a large limb had been sawed off, at http://www.backyardnature.net/n/12/121125sf.jpg.

A view of the mushroom from below, showing its curiously puffy growth, and lack of gills is at http://www.backyardnature.net/n/12/121125sg.jpg.

Lacking gills, this member of the polypore group of mushrooms drops its spores from tiny holes or pores on the lower surface. The pores seen below a dissecting microscope are shown at http://www.backyardnature.net/n/12/121125sh.jpg.

In that image most of the pores are still covered with a yellowish membrane. Apparently the membrane stays in place until the spores are mature and ready to fall. In fact, all the pores on the undersurface of the mushroom when it was photographed were covered. Only after waiting a few days, when the mushroom was beginning to fade and maggots had begun tunneling through its flesh, did the pores begin to open, enabling the last picture, and even there you can see that most pores are still covered. This was an interesting discovery, one I've not seen in print.

Among mushroom eaters, this distinctive mushroom is one of the most famous, and one of the best tasting. It's Chicken of The Woods, sometimes also called Sulphur Shelf, LAETIPORUS SULPHUREUS. Back during my hermit days in Mississippi I ate bushels of this mushroom, for it was abundant and often much larger than the one in our picture. About half of the mushroom, the thicker part nearest the wood, is too tough to eat, but the rest is somewhat fibrous like the flesh of chicken breast. Fry it in butter with onions, garlic and chili peppers, scramble it with eggs, and you have some of the finest eating imaginable.

I didn't pick the one in our picture, though, since it was the only one I've seen here, plus it was more infested with maggots than I like.

Usually Chicken of The Woods is a saprobe, which means that it decays wood on dead trees. However, under the right conditions it can become parasitic, sapping nutrients from its host tree, and causing a brown heart-rot. The one in the picture appears to have gone parasitic, for the live oak tree it was growing from appeared healthy, except for the wound formed by sawing off the big branch.

Chicken of The Woods is easy to identify, though there are some non-edible species beginners might confuse it with. To be sure you have a Chicken of The Woods, you should be in the eastern half of North America, or thereabouts, confirm that on the mushroom's undersurface there are pores, not gills, and that the mushroom grows from a tree trunk, and not from roots below the ground or at the ground's surface. Chicken of The Woods normally occurs on oaks so if you find it on a different kind of tree you should be especially wary.

As with many organisms, gene sequencing techniques have revealed a lot of genetic diversity and complexity where earlier we thought things were straightforward. What we're calling Laetiporus sulphureus here recently has been shown to actually be six species that all look alike but occur in different ecosystems and/or perform different ecological roles. However, this information hasn't filtered down to folks like us, so the best we can do is to keep speaking of Laetiporus sulphureus as we did in the old days, waiting to be put right on matters at a future date.

*****

ZYGNEMA ALGA
We've seen that the quiet waters pooled along our little Dry Frio River running behind the cabin contain the green alga Spirogyra, with its strands of chloroplasts spiraling elegantly through its fairly transparent cells. Our neat microscopic image of Spirogyra with its spiraling chloroplasts is at http://www.backyardnature.net/n/x/spirogyr.htm.

Thing is, the Spirogyra filament in that picture was found in open water, so I never got to learn what a colony or mass of Spirogyra looks like in its natural environment. I read that it looks like bright green fuzz in shallow water, so when I saw such a thing in a stagnant pool along the Dry Frio this week, I figured it was Spirogyra. You can see the green fuzz at http://www.backyardnature.net/n/12/121125al.jpg.

Before fixing in my mind that this was what a colony of Spirogyra looked like in the field, however, I knew I needed to confirm the identification by looking at the alga under the microscope. Once the filaments were under the microscope I did indeed see Spirogyra, but Spirogyra was only part of a mixture of very different looking filaments. Maybe 90% of them looked like what you can see at http://www.backyardnature.net/n/12/121125am.jpg.

There's a tremendous difference in appearance between this and Spirogyra. However, even seeing what's in the photo, I wasn't willing to give up on the idea that I was seeing Spirogyra. That's because when sexual reproduction -- the act of conjugation -- takes place in Spirogyra, a dark, spherical zygospore is formed. The zygospore is tough and can overwinter to germinate in the spring into a new filament.

However, in Spirogyra only one zygospore forms per cell. You can see in our picture that each cells contain two dark blobs. Also, Spirogyra zygospores seen under a microscope appear to have smooth surfaces, while the dark blobs in our green-fuzz alga seem to have "spiky-hairy" or fibrous surfaces.

Finally deciding that this wasn't Spirogyra, I did a general image search on "green filamentous algae fuzzy" and eventually came upon pictures matching ours. What we have here is the genus ZYGNEMA, described as a free-floating mass of filaments forming a yellow-green to bright green, tangled mat. Each algal cell contains two chloroplasts arrayed one after the other along the axis of the cell. Often the chloroplasts are described as "star shaped," or stellate, in an attempt to say that the surfaces look spiky-hairy, as in our photo.

Zygnema is actually a rather common freshwater alga and often it's found growing with Spirogyra. About a hundred Zygnema species are recognized but even specialists have a hard time distinguishing them. Often when studies are done on eutrophied bodies of water -- waters in which pollution acts as fertilizer, causing a population explosion among algae, which affect the water's oxygen content and sedimentation rate -- Spirogyra and Zygnema are mentioned as prominent species involved with the eutrophication.

*****

AGATE
In cobblestone fields along the little Dry Frio River behind the cabin you can find banded rocks such as the one shown at http://www.backyardnature.net/n/12/121125ag.jpg.

That's an agate. To be an agate, a rock must overwhelmingly consist of quartz, which is silicon dioxide, and it must display more than one color. Many agates display alternating bands of colors like the one in the picture, and can be referred to generally as "banded agate." Some banded agates are much more colorful than ours. "Argentina Condor Agate" is a form of banded agate displaying vibrantly hued bands of red, yellow, purple and other colors. All agates are not banded. "Eye agates" may show eye-like designs of different colors in a rock matrix of only one color.

Agates constitute a variety of the rock type known as chalcedony, which means that it's basically quartz adulterated with other elements, especially iron and aluminum. It also means that when the rock breaks it forms fairly smooth, even "waxy" faces, and the faces typically are not flat. They tend slightly to curve in or out -- to form concavities and convexities. This feature is described technically as "displaying conchoidal fracture."

On the planetary level, most agates develop in holes in ancient volcanic lava. However, our agates have washed down the Dry Frio River from the Edwards Plateau uplands, and the Edwards Plateau is a huge block of sedimentary limestone. Our agates formed in holes in sedimentary material that began as mud at the bottom of a shallow sea, then over millions of years the mud was squeezed into rock by very large amounts of other mud and rock above it. During those millions of years, silica dioxide and other minerals collected in the holes of the mud-becoming-rock, molecule by molecule, forming blobs rather in the manner by which very tiny droplets of oil emulsified in water gradually combine with one another, ultimately forming one big blob or layer of oil separate from the water. For a more detailed description of how this happens, check out a Penn State page on the matter at http://www.rps.psu.edu/0109/form.html

*****

FEATURED ESSAYS FROM THE PAST:

"Dog Guru," from the May 15, 2011 Newsletter, at http://www.backyardnature.net/n/p/110515.htm.

"Dog at The End of The Road" from the July 11, 2004 Newsletter, at http://www.backyardnature.net/n/p/040711.htm.

*****

Best wishes to all Newsletter readers,

Jim

All previous Newsletters are archived at http://www.backyardnature.net/n/.

Visit Jim's backyard nature site at http://www.backyardnature.net