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

April 28, 2013

BLACK-CHINNED HUMMINGBIRDS
Michael Overton's "Birds of Uvalde County" checklist lists nine hummingbird species for our County, though eight are regarded as rare, very rare, accidental, or not present during the spring. The single species noted as common in the spring is the Black-chinned Hummingbird, ARCHILOCHUS ALEXANDRI, and that's the species mobbing local feeders nowadays, though sometimes other species do turn up, such as Rufous Hummingbirds. Therefore, when neighbor Fred invited me to visit for a hummingbird photographing session the other day, we both knew that basically I was going over to take snapshots of Black-chins. You can see a male and female about to take a side-by-side slurp at http://www.backyardnature.net/n/13/130428hu.jpg.

For birders, the big thing about Black-chinned Hummingbirds is that they're the only North American hummer with truly black throats. In certain light conditions other hummers may seem to have black throats, but as they dart around eventually the light catches just right on a feather or two and you see bursts of iridescent color.

In fact, even with such a nice picture as ours showing a female with a male with a seemingly black throat, I needed to study awhile before pronouncing with certainty that we had Black-chinned Hummingbirds and not, say, a Ruby-throated with its ruby throat just seeming black. Happily, I got other pictures more clearly showing some of the Black-chin's field marks, such as the one at http://www.backyardnature.net/n/13/130428hv.jpg.

It happens that just below the Black-chin's truly black throat there's a touch of iridescent violet color, visible on one of the hummers in that picture. That splash of violet really narrows down the possibilities.

Also, behind the nearest hummer's eye notice the conspicuous white spot. Several other hummer species bear such white spots, but those spots generally are smaller. The partial white collar around the nearest bird's throat also is a good field mark visible when the birds are perching.

Black-chinned Hummingbirds are fairly common summer nesters in much of the western US, southern Texas and adjacent northern Mexico. They overwinter mostly along the Mexican Pacific slope and the central Mexican highlands.

*****

RAINBOW OF A BIRD
Once again, in the sow thistles below my kitchen window, a marvelous bird turned up, this one maybe the most colorful of all our species, shown at http://www.backyardnature.net/n/13/130428c7.jpg.

That's the male Painted Bunting. A female perched not far away with her yellowish-green back, as seen at http://www.backyardnature.net/n/13/130428c8.jpg.

When such colorful little beings turn up so quietly tending their affairs you just have to wonder about the spiritual impulse evolving life forward, and admit that there must be more to the impulse than mere "urge for diversity" in accordance with basic Darwinian principles. There must be a certain gaiety in the impulse, a glad panache, a eagerness to laugh and dance and spew poetry and song.

I stood at the kitchen window thinking this, and I also thought how glad I was that I hadn't succumbed to "community standards" suggesting that I cut my sow thistle so that monocultured, evenly cut, water wasting grass can grow there. For months this sow thistle has been a blessing, first by providing me with so many delicious meals, then later by feeding such a rainbow of birds. You can know sow thistle better on our page for the species at http://www.backyardnature.net/n/h/sonchus.htm.

Birders in most of North America never have the pleasure of seeing Painted Buntings below their kitchen windows. The species nests in deep brush along the US Gulf Coast and in the south-central states as far north as Kansas. They overwinter in southern Florida, southern Mexico and most of Central America.

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FLUFFED-UP GROUND DOVES
While I dug a trench for the new nature center's water pipes, Fred called to me that he'd spotted three sparrow-sized doves basking in the morning sunlight beneath low-hanging Ashe Juniper branches. You can see one with his feathers fluffed up letting in warm sunshine and springy air at http://www.backyardnature.net/n/13/130428dv.jpg.

At first we thought they were Inca Doves, common from the US Southwest through Mexico into Central America, and distinguished by their "scaly" appearance, caused by their feathers' dark edges. Our birds beneath the junipers looked scaly but once the picture was on the laptop's screen it was clear that the scaliness was caused by feathers that -- at least in their fluffed-out, backlit state -- had pale margins, not dark ones.

Also, Inca Doves have long tails, but you can see that our bird's tail is a stubby little thing. And note the large, dark spots on some of the feathers. Inca Doves don't have such dark spots.

So, this was the Common Ground Dove, COLUMBINA PASSERINA, occurring from southern California and southern Texas to Florida, south through Mexico into much of Central America, as well as in northern South America. Persnickety birders need the "Common" in the name Common Ground Dove because several other ground-dove species exist. In the Yucatan, along with the Common, we had Ruddy and Blue Ground Doves.

Within their area of distribution Common Ground Doves normally are easy to find. They like open or shrubby areas with tall grasses, or groves of trees along rivers and in open savannas. They also live in towns and suburbs, where they frequent yards and hedges.

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ESCARPMENT BLACK CHERRIES FLOWERING
At the base of a twenty-ft-high limestone cliff rising beside the little Dry Frio River behind the cabin, a tree turned up that I knew very well from back East, but it had never occurred to me that it might also be found here. You can see its leaves and flowers at http://www.backyardnature.net/n/13/130428pr.jpg.

That's the Black Cherry, looking healthy and at home here despite our proximity to Mexico's vast Chihuahuan Desert just west of us, and despite the long-term drought we're experiencing now.

The raceme of white flowers in the picture is exactly like those on the big Black Cherry next to my old hermit trailer back in Mississippi. However, the leaves of our Dry Frio tree are a bit different. Their smallish blades are held on petioles much longer than I'm used to, plus the leaves' margins are more coarsely toothed, or serrated, than leaves on trees I'm familiar with back East. You can compare the leaves in the above picture with those on the tree next to my hermit trailer at http://www.backyardnature.net/n/w/black-ch.htm.

It turns out that here in southwestern Texas our Black Cherries belong to a different variety than the typical one back East. In fact, four varieties of Black Cherry, Prunus serotina, are recognized for North America, with others farther south. Black Cherries occur in much of the Mexican highlands as well as Guatemala. You can see a distribution map showing many tropical-American "islands" of Black Cherry populations, as well as an isolated population here on the Edwards Plateau, at http://upload.wikimedia.org/wikipedia/en/c/cf/Prunus_serotina_range_map.jpg.

Our variety of Black Cherry endemic to the Edwards Plateau region of southwestern Texas is called the Escarpment Cherry, PRUNUS SEROTINA var. EXIMA. It's distinguished physiologically from other Black Cherry varieties by almost or entirely hairless leaves with more coarsely toothed margins, longer petioles, and, growing up to 50 ft tall (15m), a potential height intermediate that of the taller Eastern Black Cherry (P. serotina var. serotina) and the shorter Southwestern varieties, virens and rufula.

*****

GUAJILLO ACACIA FLOWERING
Rooted in rock fissures and between slabs of limestone forming ledges atop hills bordering the Dry Frio Valley nowadays a much branched, wiry, bushy tree species about ten feet tall (3m) is covered with white, marble-sized, puffball-like flowering heads that showed up even in this week's heavy overcast, as shown at http://www.backyardnature.net/n/13/130428aa.jpg.

A close-up of some flowering heads on long, stout peduncles is at http://www.backyardnature.net/n/13/130428ac.jpg.

The "fuzz" covering the balls consists of stamens with tiny, cream-colored, pollen producing anthers atop stiff, slender white filaments, as shown at http://www.backyardnature.net/n/13/130428ad.jpg.

In that picture you see that many more than ten stamens issue from each flower's greenish, five-sepaled calyx. Leaves on the tree are twice pinnate with numerous tiny leaflets, giving a ferny appearance, as shown at http://www.backyardnature.net/n/13/130428ae.jpg.

A few split-open fruit pods, or legumes, left over from last season remained on our tree, their beans long fallen out, as shown at http://www.backyardnature.net/n/13/130428ab.jpg.

In our area when you have a tree with such powder-puff-like flower heads, plus each individual flower produces more than ten stamens, the leaves are twice pinnate, and the fruits are legumes, the best bet is that you have an acacia, which is what this little tree is. It goes by several names, including Guajillo, Berlandier Acacia, Thornless Catclaw, Mimosa Catclaw, Round-flowered Catclaw, Huajilla and Matoral. It's ACACIA BERLANDIERI, and its various Spanish names reflect that it mainly occupies hillsides and slopes in arid northeastern Mexico, entering the US only here in southwestern Texas.

Among its names, "Thornless Catclaw" is a good one because it recognizes that most acacias are thorny, but this one isn't. Two or three low, weak spines did turn up on one stem, but mostly the branches were spineless. One reason Guajillo can get by without investing energy in producing spines is that its foliage contains alkaloids making the tree toxic for browsing livestock. Even goats don't like the herbage.

Just south of us, as soon as you leave the Edwards Plateau's hilly area and the vegetation becomes scrubbier, Acacia berlandieri becomes much more common than here, constituting one of the main trees in much of southern and western Texas's vast "bushlands."

Guajillo's flowers are fragrant and many kinds of pollinators buzzed around them during my visit. Some Texans say that the heavy, light-colored honey produced frp, Guajillo flowers is the best tasting of all Texas honeys.

*****

GOLDENBALL LEADTREE WITH ITS GOLDEN BALLS
At the edges of limestone cliffs overlooking the Dry Frio River Valley sometimes you find intricately branching, somewhat open trees about ten feet tall (3m), which nowadays are issuing both leaves and flowers, as shown at http://www.backyardnature.net/n/13/130428le.jpg.

The trees' large leaves are twice compound, like the North's Honeylocusts, as shown at http://www.backyardnature.net/n/13/130428lf.jpg.

The yellowish flowers are arranged in fuzzy, spherical heads, as shown at http://www.backyardnature.net/n/13/130428lg.jpg.

By now we know that the heads' fuzziness is produced by stamens extending well beyond the close-packed flowers' corollas. A close-up showing individual flowers with ten stamens arising from yellow corollas, the stamens and styles themselves lemon yellow, is at http://www.backyardnature.net/n/13/130428lh.jpg.

This is a typical combination of field marks for trees and shrubs in our arid zone -- ferny, twice-compound leaves, tiny, sweet-smelling flowers closely packed in spherical or elongate heads atop a sturdy peduncle, and numerous stamens issuing from the individual corollas. These features help us recognize the Mimosa subsection of the vast Bean Family, so here we're dealing with a tree related to the acacias, locusts, mimosas, albizias, and other such trees belonging to the same Bean Family "tribe." We know it's not another acacia because its flowers produce only ten stamens each.

This pretty little tree goes by several names, including Goldenball Leadtree, Littleleaf Leadtree, Wahoo Tree and Lemonball. It's LEUCAENA RETUSA, endemic to arid northeastern Mexico, a few counties in southwestern Texas, and the southeastern corner of New Mexico. It specializes in rocky, limestone areas and dry canyons

And this is yet another attractive, pollinator-attracting native species with enormous potential for growing in rock gardens and use in xeriscaping in general. Its open form invites plantings of shorter plants below it.

*****

FLOWERING PRICKLYPEARS
In the April 7th Newsletter we looked at the first flowering pricklypear cactus species in our area, one in thin, rocky soil atop a high hill. That species, Opuntia atrispina, turned out to be a different species from what's growing abundantly on our hills' lower slopes and on the valley floor. I've been waiting for the next flush of pricklypear flowering to begin, and now it has, as you can see at http://www.backyardnature.net/n/13/130428op.jpg.

A close-up shows how the rose-like, rose-tinted flowers cluster atop the pads at http://www.backyardnature.net/n/13/130428oq.jpg.

A view inside a blossom showing it colonized by beetles, and from its center arising a thick, pink style with a large, yellow, oval stigma atop it is at http://www.backyardnature.net/n/13/130428or.jpg.

Noting these colors was useful because they vary from species to species. Spine color, number and configuration of the confined area they arise from -- their "areoles" -- also is important, so they are shown at http://www.backyardnature.net/n/13/130428os.jpg.

Already we've identified the abundant cactus on the valley floor and surrounding hills' lower slopes as the Texas Pricklypear, Opuntia engelmannii var. lindheimeri. Since the ones on the valley floor haven't begun flowering yet and the individual pictured above was near the crest of a limestone hill, I had hopes that this would a new species for us.

However, using the key to pricklypears available online in the Flora of North America, of the 34 pricklypear species known to occur in the US, the key led me directly to our plentiful Texas Pricklypear. You can try your own hand at IDing the flowering cactus shown in our photos at http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=123045.

You can see our Texas Pricklypear adorned with large fruits, or "tunas," as one appeared last September at http://www.backyardnature.net/n/h/tx-prick.htm.

I still have hopes of finding other pricklypear species here, but I won't be able to identify them until they flower.

*****

A PURPLE-HUED GRASS ON THE VALLEY FLOOR
This week the weather in our area has been warm enough but mostly overcast and with only one little shower that hardly settled the dust. In the resulting subdued light the Dry Frio Valley looked somber, but pretty, with a patchwork of soft greens emerging. Also, here and there on the grassy valley floor there were eye-pleasing patches of diffuse purple, as shown up front at http://www.backyardnature.net/n/13/130428as.jpg.

Up close, clumps of this purple-topped grass are composed of many wispy stems with modest blades mostly clustered at stem bases, as shown at http://www.backyardnature.net/n/13/130428ar.jpg.

Closer still, the grass's purplish, unusually narrow individual flowers --or "florets" in grass terminology -- are seen to bear very long, slender, stiff, needlelike bristles, or "awns," which you can see at http://www.backyardnature.net/n/13/130428at.jpg.

And much closer yet, each flower reveals itself as bearing three awns, shown at http://www.backyardnature.net/n/13/130428au.jpg.

Until I saw the three awns shown in the last picture, I had no idea who the grass was causing the purple patches, but seeing those awns suddenly it occurred to me that we've already examined this species. Last September we looked at Purple Three-awn Grass, Aristida purpurea, and that's what we have again. Except that last September the grass was dry and straw-colored, and the awns atop the grass's matured grains stuck out at right angles to the grains, giving the fruiting heads a spiky look, as shown in our archived photo at http://www.backyardnature.net/n/12/120923t3.jpg.

What a thing that a grass looking so peaceful and harmonious with the spring landscape can in the fall take on such an aggressive, skinhead-like look. And isn't it nice that by noticing the basic structure of things, true identities are discovered, no matter what the cosmetics or seasonal context?

*****

LEMONYELLOW IRISES
Already a couple of months ago irises in Uvalde 35 miles south of us and 780 feet lower in elevation were blossoming, but here the flowers on our irises beside the cabin didn't open until this week. You can see a couple of them at http://www.backyardnature.net/n/13/130428i4.jpg.

Now, an iris is a wonderful thing, something you just want to stand and look at when it blooms, but you can't say much more about its loveliness and desirability than that -- without getting saccharine or maudlin, at least -- so here we'll talk about something else interesting about it, which is its identity.

For, between 260 and 300 iris species are thought to exist worldwide. Many species can show up in our gardens, and the species have been hybridized and gene-manipulated to the point that it's almost funny. In other words, when you see an iris, often there's a good story about its ancestry. So, what's the story for the iris in our picture?

Once you have a name, you can look up the history. Therefore, beginning the identification, first you notice that the plant is about knee high with substantial stems overtopping the leaves. That eliminates a good number of species right there, which are essentially stemless or never grow over ankle high. Also, some iris species develop from bulbs while others arise from rhizomes. With a finger I poked around enough in the dirt at our iris's base to get a peek at a rhizome, not a bulb, so that field mark also eliminated quite a few species. Next a blossom was analyzed. You can see one in all its yellow splendiferousness at http://www.backyardnature.net/n/13/130428i5.jpg.

Iris blossoms have evolved features not found in "ordinary" flowers. To be introduced to some terms and concepts peculiar to iris flowers -- such as the style arm, falls, stigmatic lip and standard -- visit my page at http://www.backyardnature.net/fl_iris.htm.

On our pretty, yellow blossom it's worth noting that at the base of the "falls" -- the large, petal-like items descending with dark reticulations at their bases -- there's a line of dense, stiff hairs known as the "beard." The falls of many iris species don't have beards. Also notice that the falls don't narrow to slender "hafts" at their bases, and that the three, yellow, petal-like items rising upwards don't narrow to "claws," which occur in many species. Now let's get closer, where you can more easily see the erect, fuzzy beard at the base of one of the falls, at http://www.backyardnature.net/n/13/130428i6.jpg.

Notice the single slender item arcing above the beard, with its tip pointing downward into the beard's center. That's one of the blossom's three stamens. Notice that above the stamen there's a broad, canopy-like affair notched deeply at its tip, and shallowly incised along its margins. That's the "style arm," which turns out to be part of the female pistil. The style arm is actually a much modified style, a style being the "neck" between any flower's ovary and its pollen-gathering stigma. Suspended from the style arm, right above the stamen's tip, is a low, broad lip-like thing. That's the stigma, where pollinators entering the flower searching for nectar are encouraged to leave their pollen grains to germinate, even as they pick up this flower's pollen from the stamen just beyond the stigma.

Stigma arms in some species are conspicuously fringed, are variously narrow or wide, colored differently, etc., so stigma arm configuration is important.

In my old Bailey's Manual of Cultivated Plants, our yellow iris keys out neatly to Iris flavescens, considered an heirloom species and often referred to as the Lemonyellow Iris. However, my Bailey's is old and the world of taxonomy has changed with the advent of genetic sequencing. According to the USDA's Integrated Taxonomic Information System, Iris flavescens now is lumped into the older species IRIS GERMANICA, the German Iris, a European hybrid itself, and believed to be the ancestor of many, if not most, of modern "bearded" irises featured in gardens the world over.

By the way, as the authority on our Lemonyellow Iris's taxonomy, the USDA's Integrated Taxonomic Information System depends on a South African man named Peter Goldblatt. In the early 1970s when I worked at the Missouri Botanical Gardens, many mornings I'd be busily at work when the freshly PhD'd Peter Goldblatt, a little fellow who favored turtleneck sweaters and tight jeans, would stroll in late with an irrepressibly insouciant air about him, and I figured he'd never get anyplace in the world. But now he's become the world's foremost expert on the Iris Family, and I'm the one who soon gave up serious taxonomy, and that's how the world turns.

Peter is still at Missouri serving as a Senior Curator, having authored several classic botanical texts on the Iris Family.

*****

FEATURED ESSAYS FROM THE PAST:

"Remembering 'Fahrenheit 451,'" from the October 30, 2011 Newsletter, at http://www.backyardnature.net/n/p/111030.htm

"On Being a Machine," from the May 23, 2010 Newsletter, at http://www.backyardnature.net/n/p/100523.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