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

June  30, 2013

Looking for butterflies among wildflowers blooming profusely after a recent rain I was hiking across a patch of grassy prairie in the Dry Frio floodplain when I came upon the breath-robbing sight at http://www.backyardnature.net/n/13/130630fw.jpg.

The fawn moved not a hair, depending on his stillness to "make him invisible" there in his sea of windblown, undulating grass and yellow flowers.

You may recall that this time last year at this season (reported in the July 15th Newsletter) in southwestern Mississippi we saw the same thing, the resulting picture still archived at http://www.backyardnature.net/n/12/120715fw.jpg.

Notice that the Mississippi fawn was similarly positioned, and in both cases the dark hollows of their funnel-shaped ears were pointed exactly at me. The fawns may seem dazed or unconcerned, but their ears directed so precisely at me shows that I'm being monitored.

In this area we have large numbers of both White-tailed Deer and Axis Deer, the latter introduced from Asia, plus smaller numbers of Fallow Deer from Europe. Best I can tell from pictures on the Internet this is a White-tailed Deer, though the fawns of all three species are somewhat similar.


A stone's throw from the nature center there's a salt block left from last year when deer hunters claimed the area. All through the day, just about any time I glance at the block, one or more House Finches and an occasional Mourning Dove can be seen atop the block or at its base. Sometimes it's as if the local House Finch community uses the block as a social gathering point, for among block visitors there's usually a lot of flitting about and excited calling. Other times the birds just work at acquiring salt from the hard, smooth block. You can see a couple of males at work at http://www.backyardnature.net/n/13/130630fi.jpg.

Often the birds just peck at the salt, as the one on the right is doing. However, notice how the bird on the left holds his forward-sliding head so that the side of his beak scrapes over the block's surface. Sometimes they'll tilt their bodies forward and slide their beak bottoms along the block's top. Are their tongues hanging out, licking the salt? It happens so fast I can't see and it doesn't show in my pictures.

I worried a little that the salt might harm the birds, so on the Internet I sought information on the matter. There's not much to be found, except that Sally Roth's 2012 book Attracting Songbirds to Your Backyard, which is partly accessible via Google Books, writes that "Goldfinches, house finches, purple finches, grosbeaks, native sparrows, doves and other songbirds flock to salt blocks to peck at the mineral."

It seems that thick-billed finches as a group are especially attracted to salt. With regard to whether the salt might be bad for them, Roth says that "No studies have been done on whether salt harms them. Birds generally know what they can and cannot eat."


A sparrow landed in the birdfeeder of my neighbor Phred, as shown at http://www.backyardnature.net/n/13/130630sp.jpg.

Note that below the solid rusty crown there's an eye stripe that's neither pure white, like a Chipping Sparrow's, nor dusky, like a Rufous-crowned Sparrow, and below the eye stripe a dark line passes through the eye, which both those species display. In this part of the country the Chipping and the Rufous-crowned Sparrows are the only summer residents displaying this combination of field marks, so which is it?

Rufous-crowned Sparrows have dark "whiskers" -- dark lines slanting down from the base of their lower mandibles -- which Chipping Sparrows lack. This bird displays a hint of such whiskers. Chipping Sparrows exhibit white wing bars, but not Rufous-crowned Sparrows; our bird presents only a hint of such bars.

Apparently this is an immature bird on which the field marks aren't yet fully developed -- no pure white eye stripe or conspicuous white wing bars if it's a Chipping Sparrow, and no definite whiskers if it's a Rufous-crowned. I just couldn't decide which it was so I sent the picture to my old birding buddy Jarvis in North Carolina, who normally gets his bird IDs right. He replied:

"The very white eye stripe, the lack of a conspicuous whisker mark, and the presence of wing bars, though faint, confirm my impression that it's a Chipping Sparrow."

Well, now that he mentions it, it's true that Rufous-crowned Sparrows don't develop white wing bars even as poorly developed as the ones in the picture, and that whiskers of even immature Rufous-crowned Sparrows are more solid than the thin line on ours.

Well, there's an example of how bird IDing works, and how a genuine bird expert analyzes his birds.


Our neighbor Dave invited us to his ranch to look around. One thing he showed us was a curious stratum of limestone outcropping on one of his hillsides. The white stone was honeycombed as if tunneled through by thousands of worms, some tunnels only finger wide, others big enough to put a fist in. The stone was nice but what really was exciting was the plants living in natural bowls formed wherever the honeycombed rock outcropped. For instance, there was the four-inch-tall (10cm) cactus shown at http://www.backyardnature.net/n/13/130630ca.jpg.

That picture is a bit monochromatic and bluish because we visited the hill during that magical hour after sunset known by photographers as the blue hour, after the French expression l'heure bleue. At this hour the landscape was illuminated by light reflected from the sky. It happens that light of shorter wavelengths -- at the blue end of the light spectrum -- scatters more readily in the atmosphere than red light of longer wavelength, so that early evening everything was tinted blue, and camera seem to document the phenomenon more than our own eyes.

Anyway, it was the blue hour and the amazing full moon you probably noticed last weekend was rising over the hill, so really the cactus was lighted as much by the Moon as by the dimming sky. The above picture is a time exposure of four seconds duration. The fuzzy thing near the cactus's center is a feather caught among the spines. A close-up of the cactus's spine clusters appears at http://www.backyardnature.net/n/13/130630cb.jpg.

From the cactus's barrel shape and the distinctive disposition of its spines I recognized it as a kind of hedgehog cactus, genus Echinocereus. However, about 23 species of hedgehog cactus are known to live in North America, and several occur in southwestern Texas, so which one was this?

The white spines spreading so systematically from their long, slender base areas, or areoles, with no spines arising from the narrow areole surface between the bases of the marginal spines indicate that this is ECHINOCEREUS REICHENBACHII, mostly known as the Lace Hedgehog or simply Lace Cactus.

The Lace Hedgehog's main homeland is northern Mexico's Chihuahuan Desert but in the US its distribution extends up through the central states as far north as Kansas and Colorado. That makes this the most northerly occurring Echinocereus, and one treasured by rock gardeners for its ability to survive fairly cold temperatures.

The Flora of North America says, "The taxonomic and geographic boundaries among the segregate species or numerous proposed infraspecific taxa of Echinocereus reichenbachii remain nebulous and controversial." In other words, the experts are having a hard time fitting this species into a decent pigeonhole, even in this time of promiscuous gene sequencing.

I like the idea of finding a nebulous and controversial Lace Hedgehog lighted by moonlight on Dave's hill. Lace Hedgehogs produce glorious blossoms large out of all proportion to their small body size, and that's something I hope to eventually see and show you.


Maybe the most exciting find on Dave's ranch was the fern shown growing from fissures in limestone rock forming the rocky bottom of a dry arroyo at http://www.backyardnature.net/n/13/130630fl.jpg.

I'd never seen a frond exactly like that, but as soon as the blade was turned over a certain feature immediately suggested that this new-for-me species belonged to a group of ferns of which we've already found several species in this area. That was a shocker, because already I was astonished thaty so many of this group had been found. You can see what appeared below the frond at http://www.backyardnature.net/n/13/130630fm.jpg.

The tiny, spherical, shiny, brownish things are baglike sporangia, inside which spores are formed, and the meaningful feature that caught my eye is that the sporangia arise along the frond's down-curving pinna margins. Most sporangia on the undersurfaces of fronds are arranged in groupings called sori, and the sori are strewn across the fronds' lower surface, often in systematic and distinctive patterns. This arising from inside down-curving margins is characteristic of the group of ferns known as the lip ferns, genus Cheilanthes. Cheilanthes is by far the largest and most diverse genus of arid-land (xeric) ferns.

Having recognized the genus, it was easy to look up on the internet the various species occurring in this region. Soon I knew I had a challenge.

For, the Flora of North America makes clear that two very similar, closely related fern species occur in our area: The White-footed Lip Fern, Cheilanthes leucopoda, of very limited distribution, known only from four limestone-bedrocked counties here in southwestern Texas and a spot across the Rio Grande in Mexico's Coahuila state; it has straw-colored petioles and its hairs are not tipped with sticky glands. The other species, Kaulfuss' Lip Fern, Cheilanthes kaulfussii, has reddish-purple to dark brown petioles and its hairs are indeed tipped with sticky glands. It's distributed from South America north into our part of Texas, mostly on igneous outcrops, so it's much more widely distributed.

Thing is, our fern is somewhat intermediate, possibly a hybrid. Its on limestone, its petioles are straw colored and its hairs are predominately not tipped with glands -- all like the White-footed Lip Fern. However, there are many NON-stalked glands dotting the veins' surfaces, which the Flora of North America doesn't mention. You can see what I mean at http://www.backyardnature.net/n/13/130630fn.jpg.

Pictures on the Internet of vein hairs on Kaulfuss' Lip Fern show the hairs as very conspicuously tipped with glands.

So, I've met a new lip fern species, and my impression is that it's the White-footed Lip Fern, but maybe bearing some genes of Kaulfuss' Lip Fern. And this is great, because neither of those fern species is much documented. By documenting this find we're helping future researchers who will be very happy, and maybe perplexed, to see what we've found.


On our visit to Dave's ranch ten miles south of us we descended in elevation from our position on the Edwards Plateau's southern slope so slowly that it wasn't noticeable, except in terms of vegetation change. Along the road as we traveled, more and more species appeared typical of the deserty, acacia-rich scrub forest farther south and west of us. In a prairie patch at the entrance to Dave's ranch a plant I've not seen at our higher elevation appeared, as shown at http://www.backyardnature.net/n/13/130630al.jpg.

It was so late in the afternoon that the setting sun's rays exploded within the eight-ft-tall (2.4m) bush's white flower-spikes. Wind violently shook the flowers, spectacularly showing them off against their dark backgrounds. The bush seemed to be motioning to be noticed. As I drew near, before I could see any detail of flower or leaf the bush's fragrance, dizzying and vanilla-like, engulfed me. Who would have thought that such a wild, diffusely growing bush might smell so good, and what plant could this be? Up close, the flowers' shapes provided a big hint, as you can see at http://www.backyardnature.net/n/13/130630am.jpg.

The blossoms with their curved corolla tubes and asymmetrical faces look much like flowers of verbena and lantana, which are members of the big Verbena Family, the Verbenaceae, so now I knew into which family to look once I began "doing the botany."

The fragrant, gesticulating bush revealed itself as ALOYSIA GRATISSIMA, among whose common names are Whitebrush, Beebrush, Jazminillo (Little Jasmine), Hierba de la Princesa (Princess Plant) and Chaparro Blanco. Whitebrush occurs in arid parts of the southwestern US and most of Mexico, plus there's another population occupying a large part of southern South America.

While to me Whitebrush is extremely attractive, ranchers lower down regard it an aggressive weed of rangeland that forms thickets, especially on disturbed ground. The thickets provide wonderful protective cover for wildlife, but when horses eat Whitebrush's herbage they develop a rickets-like disease.

Still, Whitebrush strikes me as an outstanding candidate for being grown in lawns in arid areas. Throughout the year it flowers prolifically after rains, and survives extended droughts and very high temperatures.

And surely no fragrance could be more delightful than that very generously produced by this plant.


In our recent June 9th Newsletter we looked at a very common roadside weed with narrow, silvery-hairy leaves and handsome, purple corollas with yellow "noses" of large anthers. That was the Silverleaf Nightshade, shown at http://www.backyardnature.net/n/h/solanum1.htm.

Silverleaf Nightshades still are flowering, plus in slightly moister, even shady spots, there's a similar flowering plant also producing purple corollas with yellow "noses," but that plant's leaves are greener and broader. These are closely related Western Horsenettles, SOLANUM DIMIDIATUM, shown at http://www.backyardnature.net/n/13/130630sm.jpg.

A close-up of the yellow "nose" comprising five pollen-producing anthers gathered around the ovary's style appears at http://www.backyardnature.net/n/13/130630sn.jpg.

These two species are so similar and closely related that you wonder why the name givers decided that the silvery leafed one was a nightshade but this one is a horsenettle. Probably it's because the Silverleaf Nightshade bears fewer spines or none at all, while our Western Horsenettle nearly always produces spines worthy of consideration when going barefooted.

Western Horsenettle is native to the US south-central states from Kansas to our area, plus it's invasive in other southern states. As with many species in the genus Solanum the fruits are poisonous and are probably responsible for “Crazy Cow Syndrome,” which expresses itself with staggering, tremors, and lack of coordination. In humans it can cause similar symptoms and in high enough doses finally leads to kidney failure, inability to breathe, and death.


Beside the community's low-water ford across the little Dry Frio River a tub-size population of an unusual Sedge Family member caught my eye, shown at http://www.backyardnature.net/n/13/130630cx.jpg.

A close-up of a fruiting head appears at http://www.backyardnature.net/n/13/130630cy.jpg.

At first I thought the plant belonged to that huge and diverse group of monocotyledonous, grass-like plants known as sedges, genus Carex. However, the achene-type fruits of Carex develop inside baglike "perigynia," but when I crumbled this plant's head in the palm of my hand instead of seeing achenes inside perigynia I found naked achenes with slender bristles arising at their bases, as in the Sedge Family group known as the spike rushes, genus Eleocharis. But spike rushes produce just one flower head atop each slender stem, and you've seen that these plants bear several. This plant was something I hadn't seen...

It turns out that the plant belongs to the Sedge Family genus Fuirena, a genus that's new to me. Our plant is the Western Umbrella Sedge, FUIRENA SIMPLEX, a mostly tropical plant occurring from northern South America up through the Caribbean Area, Central America and Mexico into the US south-central states as far north as Nebraska.

As a group, members of the genus Fuirena are referred to as umbrella-grasses. That's unfortunate because they're not grasses -- not members of the Grass Family. Also, another much better known group of Sedge Family species, genus Cyperus, also are called umbrella-grasses. Fuirena is such an obscure group of plants that no good common name has arisen for them.

In Texas several species of umbrella-grass occur. Maybe the best field mark distinguishing our plant is that the cylinder around the stem formed below where the leaf attaches to the stem (the sheath) isn't hairy like sheathes on the other species. You can see one of our plant's nearly hairless sheaths at http://www.backyardnature.net/n/13/130630cw.jpg.

Of what use is such an obscure, little-known plant?

The main activity of the Universe shows itself to be an evolution toward ever greater diversity and sophistication based on interrelatedness of parts. The Western Umbrella Sedge contributes to that diversity, and helps maintain the Dry Frio ecosystem's sophisticated interrelatedness just by being, by photosynthesizing and issuing oxygen for us all, and by producing little pink achene-type fruits which this or that bird sometime later will be very happy to eat.


Spanish Bayonet, YUCCA ALOIFOLIA, is a native yucca of Central America, Mexico and the US Deep South's coastal areas, from Virginia to Texas. Here we're too far inland for it to be native to our area but, like folks in warmer areas worldwide, people here grow it next to their houses because it's such a pretty, attention-getting plant. For example, you might remember a Spanish Bayonet we found in Pisté, Yucatán not long ago, shown at http://www.backyardnature.net/n/12/120318yu.jpg.

Here on the gravelly floodplain of the little Dry Frio River there's a clump of Spanish Bayonet looking a little different from what's shown in that picture, shown at http://www.backyardnature.net/n/13/130630yu.jpg.

In that picture notice how the flowering yucca at the left arises from an arm-thick stem cloaked with dead blades and lying on the ground. All the flowering stems in the population arise from such reclining stems and none of their flowers rise much more than head high. That's so different from the soaring, tree-like Spanish Bayonets we've seen in Mexico that at first I thought they might be something different. Therefore, I took pictures of field marks so that later I could "do the botany."

A portrait of three nodding flowers appears at http://www.backyardnature.net/n/13/130630yv.jpg.

The yucca species most likely to be confused with Spanish Bayonet is the very closely related Spanish Dagger, Yucca gloriosa. However, Spanish Dagger flowers produce ovaries that are somewhat fused with their white, petal-like "tepals," while Spanish Bayonet ovaries usually rise on a short pedestal, or "stipe." A flower from one of our Dry Frio plants was broken open so could see whether the ovary stood upon a short stipe or not. You can see for yourself at http://www.backyardnature.net/n/13/130630yw.jpg.

The slightly greenish, elongate ovary in the blossom's center is indeed elevated upon a short stipe, so that's one confirmation that we have Spanish Bayonet, not Spanish Dagger.

Also, blade edges of Spanish Bayonet are very finely toothed and can cut your skin if you brush against them, while blade edges of Spanish Dagger are smooth. It was easy enough to feel closely spaced, very tiny, raspy teeth along our plants' blades' edges, so there was another confirmation that we had Spanish Bayonet, not Spanish Dagger. Moreover, once I looked closely it was clear that the teeth on Spanish Bayonet's leaf edges aren't at all like the usual broad-based spines or saw-teeth on most other scratchy-edged leaf margins. You can see a close-up of our plant's teeth at http://www.backyardnature.net/n/13/130630yx.jpg.

So, what accounts for our Spanish Bayonets displaying such a different growth form from the ones seen in Mexico?

Spanish Bayonets start live growing upright, but when they get to a certain height tend to fall over. At that point the growing tip curves upward, forming such plants as our pictures show.

Once a stem produces flowers it dies back. However, normally buds occur along the stem, so when the tip dies, the bud closest to the trunk's tip begins issuing leaves and becoming the new "top of the plant." Later it will also flower, and also die back, yielding to the next bud along the ever-lengthening stem.


At the end of our ranch tour Dave showed us a fossil he'd found, shown at http://www.backyardnature.net/n/13/130630fo.jpg.

The underside appears at http://www.backyardnature.net/n/13/130630fp.jpg.

The fossil is about 4 inches long (10 cm).

All the rocks in this area are early Cretaceous in age, and from the looks of outcrops on the hillsides of Dave's ranch I'd guess that his strata are of the Glen Rose Formation, like ours farther upslope at the Center. Knowing the approximate age of the rocks -- Glen Rose rocks are 108-113 million years old -- was a big help in identifying the fossil.

The fossil is snail like, so it's a gastropod. Using a search engine for images on the keywords "Glen Rose gastropod" I got matching pictures for the genus Lunatia, a kind of predatory sea snail in the family Naticidae, known collectively as moon snails. An early Cretaceous Lunatia often mentioned as being found in our area is Lunatia pedernalis, and on the Internet pictures of that species are similar enough to Dave's fossil that that's the name I'm filing it under here until an expert tells me otherwise. Sometimes this species is listed as Prisconatica pedernalis.

Though Lunatia pedernalis became extinct millions of years ago, members of the genus Lunatia still can be found. For example, along the Atlantic shore of northeastern North America there's the Northern Moon Snail, Lunatia heros. A good guess is that the general behavior of that species probably is similar to that of the snail of over a hundred million years ago that formed Dave's fossil. The Wikipedia page for the Northern Moon Snail (http://en.wikipedia.org/wiki/Lunatia_heros) says of that species that "The powerful foot enables this gastropod to plow under the sand in search of other mollusks. Upon finding one, it 'drills' a hole into the shell with its radula, releases digestive enzymes, and sucks out the somewhat predigested contents."


The main reason Dave had invited us to his ranch was because he wanted to show us a special geological formation outcropping in a small area at the bottom of an arroyo, an arroyo being a streambed that's dry most of the time. Finally reaching the outcrop it was easy to see what Dave was talking about. All around us were outcroppings of more or less horizontal strata of limestone typical of the region, but here a dark rock seemed to extrude from the ground, its upper surface eroded into smoothish bumps, but the sides revealing a strange fibrous texture, the fibers standing vertically and parallel with one another. Dave had brought a hammer so he knocked off a hunk and handed it to me. You can see that where the rock broke from the dark outcrop its surface was smooth and shiny, at http://www.backyardnature.net/n/13/130630cc.jpg.

Notice all the flat surfaces scattered across the rock's face. This shows that the rock is crystalline. When it broke from the outcrop the breakage occurred along crystalline "cleavage planes" inside the rock.

A crystal is defined as a homogenous solid formed by a repeating, three-dimensional pattern of atoms, ions, or molecules and having fixed distances between constituent parts.

So, a crystal is pure (homogenous) and it becomes crystalline because its atoms, ions or molecules, during the crystallization process, consistently order themselves in a particular manner, depending on the shape and/or electrical charges of the atoms, ions or molecules. One outcome of this reality is that a crystal's shape is determined by the arrangement of its atoms, ions or molecules. In other words, a crystal's shape indicates to us how the crystal's component atoms, ions or molecules combined as the crystal formed.

Apparently millions of years ago something caused this tiny area of limestone to melt, forming magma. If magma cools slowly enough, crystals form -- the slower the cooling, the larger the resulting crystals. Lots of faults occur in our area, so maybe when one side of a fault slid past the other, the friction produced caused limestone near the fault line to melt, leading to our crystals.

Another possibility is that in our area -- though mostly to the south of where we were -- studies show that between 72 and 82 million years ago magma from deep inside the earth frequently rose up through the earth's crust, following fractures in the rock. Some of this uprisings of magma were issued as lava ejected from volcanoes, other magma barely reached the surface, and most magma didn't reach the surface at all. But wherever this magma passed, it melted nearby sedimentary rock -- our limestone -- so maybe such a nearby "igneous intrusion" melted our rock.

You can see a tiny corner of the crystalline rock Dave handed me at http://www.backyardnature.net/n/13/130630cd.jpg.

Notice the structure shaped like a shoebox squashed a little to one side. That's a calcite crystal. Calcite crystals are recognized by their rhombohedral shape, rhombohedrons being solids bounded by six rhombic planes, a rhombus being four-sided, with opposite sides parallel and opposite angles equal. You can see that the anges of this crystal are consistently either of a certain acute angle (acute angles are narrower than right angles) while the others are obtuse (more open than right angles). Chemically, calcite is CaCO3, so these angles reveal how asymmetrical molecules of CaCO3 "settle" together during the crystallization process.

Actually, by calling this a calcite crystal I'm using some imprecise and, on a technical level, possibly misleading name. For, calcite is one of the most common minerals on Earth, and over 800 different forms have been described, all with their own names. Our rhombohedrons are just one form of Calcite. For example, stalactites hanging from the roofs of caves are mostly calcite. Also, some other crystal types have this shape and our crystal might be one of them, or a transition stage between them. Dolomite crystals look like calcite crystals; special optical tests must be performed to distinguish them. Dolomite is CaMg(CO3)2, which means that dolomite is basically calcite with some added magnesium. The more magnesium, the purer the form of dolomite. And we can guess that there's a bit of magnesium in our limestone, but we don't know how much.

Traditionally certain people have regarded calcite crystals as having metaphysical properties. Web pages can be found saying that calcite is a protecting, grounding and centering stone that can help bring inner peace. Also, "Calcite can ameliorate arguments in a relationship, and help maintain a practical balance between the people in the relationship."

If you drop a bit of acid on a calcite crystal -- even a weak acid like vinegar -- it'll fizz, at least a little, as the hydrogen in the acid combines with the calcium carbonate forming gaseous carbon dioxide.



"Tapdancing with Sandpipers," from the September 25, 2011 Newsletter, at http://www.backyardnature.net/n/p/110925.htm

"It's the Sign..." from the February 18, 2008 Newsletter, at http://www.backyardnature.net/n/p/080218.htm


Best wishes to all Newsletter readers,


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