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 21, 2013

MINISCULE SNAKE IN A JAR
On Monday afternoon neighbor Sharla dropped by with a car full of kids and a glass baby-food jar in which she'd deposited what's shown at http://www.backyardnature.net/n/13/130421bl.jpg.

She'd found the four-inch long (10cm) snake in her house and didn't seem sure whether to be horrified or have a good laugh. On principle she didn't like snakes in her house, but this one was so tiny that even if it had wanted to bite, it couldn't have gotten hold of a finger. I was impressed that she'd noticed the tiny critter's scales and realized that it was a snake and not a worm.

In Mexico we've seen snakes this small and smaller, such as the Goudot's Thread Snake, Leptotypholops goudotii, at http://www.backyardnature.net/mexnat/goudot.htm.

My Audubon field guide for reptiles informed me that Sharla's jar snake was the Texas Blind Snake, LEPTOTYPHOLOPS DULCIS, thus belonging to the same genus as the thread snake we'd seen in Mexico.

Actually, identifying the snake to species level involved a bit more than just matching pictures in the field guide, for in our area we also might find the very similar Western Blind Snake, Leptotyphlops humilis. However, on the Internet a page describes how to separate them:

"If the scale pattern ... does not include separate supraocular scales between the lateral scale over the eye and the spinal scale, the snake is a Western Blind Snake (L. humilis); but if the supraocular scales are present, it is a Texas Blind Snake (L. dulcis)."

On that page you can see a diagram showing the scales involved, at http://bugsinthenews.info/?p=1311.

The closest close-up of the head scales I could get is the one shown at http://www.backyardnature.net/n/13/130421bn.jpg.

Consulting the scale diagram, we can see that the supraocular scales are well separated, so that means Texas Blind Snake. In that close-up you can also see that the snake's eyes are vestigial and covered by opaque head scales.

The field guide states that Texas Blind Snakes are nocturnal and seldom seen except on evenings following heavy summer rains. They most frequently occur in damp soil under slabs of rock, logs or other such things, where it feeds almost exclusively on termites, ants and ant pupae.

Texas Blind Snakes occur from southern Kansas to southeastern Arizona, south into arid northern Mexico.

*****

A YOUNG SCISSOR-TAILED FLYCATCHER PASSING THROUGH
Hot wind gushing up from Mexico's Chihuahuan Desert, dust and sweat stinging the eyes, glaring sunlight, wind beating the ears, and then this buoyant kite, silvery like a fleck of dusty sky that mid-afternoon suddenly landing on a fencepost, the kite tail trailing in the wind, and you can see exactly what it looked like at http://www.backyardnature.net/n/13/130421fc.jpg.

It's the first Scissor-tailed Flycatcher, TYRANNUS FORFICATUS, I've seen since arriving here, a young one with a long tail not nearly as long as an adult's, and pinkish sides not nearly as pink as an adult's. He's a bird with some kind of looking-the-place-over look in his face, and I hope he liked what he was seeing, for beholding Scissor-tailed Flycatchers floating in the wind of hot summer days is a pleasure.

But, the young bird seemed unimpressed, half-wearily flying into the wind a bit before swooping to snap a bug in midair, then landing on another fencepost farther away.

Well, good luck to him, wherever he decides to spend the summer.

Scissor-tailed Flycatchers nest in the south-central US from southern Nebraska south into northern Mexico, and overwinter from southern Mexico through Central America, on the arid Pacific slope, to Panama. The species may be expanding its distribution because of forest clearing on both breeding and wintering grounds.

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UNAMERICAN GOLDFINCH
Once again foraging among the sow thistles below my kitchen window a bird species showed up that most American birders, unless they're in the US's arid Southwest or western coastal region, just never see. You can see it, its beak sticky with white latex that's oozed from the sow thistle's tissue injured by the bird's foraging, at http://www.backyardnature.net/n/13/130421gf.jpg.

Even if you've never seen this species, with it's small size, thick, short beak, yellow underparts and black top, this bird might remind you of a goldfinch, which it is. However, it's not the American Goldfinch so common in many habitats from coast to coast in the US and adjacent Canada. It's the Lesser Goldfinch, CARDUELIS PSALTRIA, common in arid environments from northern South America north to the southwestern US and the Pacific coast states as far north as southern Washington. You can see how different the male Lesser's top parts are from those of the American Goldfinch at http://www.backyardnature.net/n/13/130421gg.jpg.

Male American Goldfinches are bright yellow above, except for a black forehead.

In more northern parts of the US Southwest, Lesser Goldfinches are only summer residents, withdrawing south during the winter. However, here in southwestern Texas, they're permanent residents, as they are in Latin America.

In the US, Lesser Goldfinches occur in two color forms. Ours with its males sporting all-black backs is the "Texas form," while farther west the males' backs turn gray-green, or olive, constituting the "Western form."

The Lesser Goldfinch is lesser because it's smaller than the American species. American Goldfinches are about 4¼ inches long (11.5cm) while the Lesser is only 3¾ inches (9.5cm). In the West the two species sometimes turn up together at birdfeeders.

*****

TEXAS PERSIMMONS FLOWERING
Last September we looked at our Texas Persimmons' black, juicy, slightly bitter fruits, which you can see and read about at http://www.backyardnature.net/n/w/tex-pers.htm.

Texas Persimmon trees are flowering now, and it's something to see, for the species is abundant here, even though it's distributed only in southern Texas and arid northern Mexico. Persimmon trees usually are dioecious, which means that their blossoms are unisexual, and occur on different trees; there are boy trees and girl trees.

A cluster of male flowers -- the one on the far left fully open -- is shown at http://www.backyardnature.net/n/13/130421dl.jpg.

In that picture, notice how the blossoms arise from last year's wood, not from the new sprout emerging from buds. In North America we have four persimmon species -- four members of the genus Diospyros -- and this feature distinguishes Texas Persimmons from the other three. A close-up of a longitudinal section of a male flower showing the blossom's interior occupied only with pollen-producing stamens (usually numbering 16 in each flower) is at http://www.backyardnature.net/n/13/130421dk.jpg.

Female flowers are much larger and fewer in each cluster, as shown at http://www.backyardnature.net/n/13/130421di.jpg.

A close look into a female flower's throat, showing four hairy styles (one style is obscured) atop a green, oval ovary -- the future black persimmon -- is at http://www.backyardnature.net/n/13/130421dj.jpg.

Something surprising to me is that in our area during this season male trees far outnumber female ones -- maybe by a ratio of ten to one. On the Internet I find no mention of such a mismatch between male and female trees, though one paper reports that individual Japanese Persimmon trees are said to develop predominantly female flowers one year and male flowers in another, resulting in great fluctuations of crop yield from year to year.

Maybe this predominance of male trees is temporarily caused by our current severe drought. Maybe the trees "know" that if they produce female flowers leading to fruits there won't be enough rainfall later on to produce fruits with viable seeds. Among persimmon species, gender roles are not written in stone. Sometimes male trees produce a handful of female flowers, and vice verse for female trees.

*****

PINK MIMOSA FLOWERING
On rocky slopes of the limestone hills framing the valley of the Dry Frio River nowadays you spot little explosions of bright pink amidst outcropping white rocks and greening clumpgrass. The half-inch wide (15mm) spheres of pinkness are clusters of good-smelling flowers borne on arching, thorny, soft-woody, knee-high "briar stems," as shown at http://www.backyardnature.net/n/13/130421mm.jpg.

A close-up of individual flowers in a head shows that the powder-puff effect is produced by stamens with pink filaments and yellowish white, pollen-producing anthers emerging from each inside each corolla, as seen at http://www.backyardnature.net/n/13/130421mn.jpg.

The stems' leaves are twice compound in the manner of locust and acacia trees, because like those species this is a member of the vast Bean Family. It's a mimosa, one often called Pink Mimosa, Fragrant Mimosa or -- like so many other woody shrubs with curved spines -- Catclaw. It's MIMOSA BOREALIS, occurring on rocky hillsides and canyon slopes from southwestern Kansas and southeastern Colorado south into arid northern Mexico.

In this part of the world, if you see a plant with such flower heads and twice-compound leaves, its stem is woody, its leaflets are small (less than half an inch long, 15mm), and from each individual flower ten or fewer stamens emerge, it's one of several possible species of Mimosa. If it were an Acacia, the flowers' stamen number would be ten or more.

Because the species' flowers are so fragrant, nicely colored and attractive to pollinators, and the plant survives on little water, it's a welcome addition in this area's rock gardens, and deserves to be planted more with xeriscaping in mind. It can be grown by collecting seeds in the fall and sowing directly where you want them.

*****

A PRIMROSE WITH THREE-INCH-WIDE FLOWERS
Sprouting from a roadcut were several ten-inch tall (25cm), branching stems atop which floated three-inch wide (8cm) blossoms so yellow on that dark, overcast morning that the flowers seemed to glow from an inner light. A picture merely hinting at the effect they produced is at http://www.backyardnature.net/n/13/130421ca.jpg.

Notice that the blossoms bear four petals, not the more typical number of five for such flower types, so that's a good field mark. The way the sizable sepals bend backwards and end with such slender tips also is a field mark, shown at http://www.backyardnature.net/n/13/130421cc.jpg.

When you see such large, yellow, four-petaled blossoms with reflexed sepals of this manner, you should think "the Primrose Family, the Onagraceae. In fact, when I saw these plants I assumed they were primroses themselves, genus Oenothera. Oenothera is one of my favorite genera because back in the 70s when I worked at the Missouri Botanical Garden in St. Louis I was sent to South America for two months to collect seeds from Oenothera species. Today I cannot see an Oenothera without remembering the broad, blue sky above the Argentine Pampas, wind screaming among jagged, wildflower-rich pinnacles of the Bolivian Andes, Paraguay's hot, dry Chaco region...

About 125 Oenothera species are recognized, and some display very limited distribution areas -- they're narrowly endemic -- so I hoped for a rare find here. However, it turns out that these spectacular little beings occur fairly regularly in prairies, meadows, pastures and savannahs in arid northern Mexico and across the border in Arizona and as far north as southern Colorado and Kansas, including most of western Texas.

They're about equally known as Western Primroses and Hartweg's Sundrops. Even their technical name is in dispute, some specialists calling it OENOTHERA HARTWEGII and others placing it in a completely different genus, naming it CALYLOPHUS HARTWEGII. My former boss at the Missouri Botanical Gardens, Peter Raven, is the one who removed this plant from Oenothera and assigned it in Calylophus, though I would most happily see it retained in its traditional genus, Oenothera.

One reason Dr. Raven banished our pretty plant from the evening primrose genus is that the stigmas of its blossoms don't look right for Oenothera. You can see the X-shaped stigma terminating a slender style drooping from the throat of a Pink Evening Primrose, Oenothera speciosa, which we saw in southernmost Texas last year, at http://www.backyardnature.net/n/12/120401of.jpg.

In Oenotheras, stigmas are supposed to be X-shaped. Now look at the stigma similarly ending the drooping style of one of our roadcut blossoms, at http://www.backyardnature.net/n/13/130421cb.jpg.

Our roadcut flower's stigma is not X-shaped at all, but rather more spherical, and only slightly four-lobed.

Well, in the world of plant taxonomy, little differences like that mean a lot. Over a hundred evening primrose species produce X-shaped stigmas, and then along comes our plant whose stigma is a slightly four-lobed sphere, so what do you do?

*****

FOUR-NERVE DAISIES
Suddenly there are so many new wildflowers appearing that I can't keep up with them. However, when I tell the locals how impressed I am by the wildflower show, they tend to shake their heads and maybe show me pictures of the Dry Frio Valley this time last year, when the drought wasn't as bad, and the valley was carpeted with gaudy wildflower color. As far as the locals are concerned, this year the wildflowers just aren't appearing, because of the drought.

Still, there are enough to keep me happy. One of the most common species in sun-baked openings on the rocky, lower slopes of our limestone hills and sometimes even along the road is the foot-tall member of the Composite or Daisy Family shown at http://www.backyardnature.net/n/13/130421tt.jpg.

To look so perky after a full day of full sunlight and an afternoon temperature of 95°F (35°C), this is clearly a tough little plant, one highly adapted for its environment. However, it's just one of a jillion little yellow-flowered daisies, so it took awhile to figure out this one's identity. First, I broke apart a flower head and saw what's shown at http://www.backyardnature.net/n/13/130421tu.jpg.

The greenish cylinders packed so closely below the disk flowers' golden corollas are the future achene-type fruits. Diagnostic features include the fact that the little mound the immature achenes arise from, the "receptacle," is not high enough to be "columnar," nor so low as to be "flat." The future achenes themselves are not separated from one another by chaffy bracts called paleae, but at their tops each one wears a crown of six or so sharp scales, which make up the pappus. Often the pappus consists of slender, white hairs, sometimes of long, barbed spines, sometimes there is no pappus... For identification purposes, these are important details.

Beneath the flower head the very fuzzy, overlapping involucral bracts, or phyllaries, also are distinctive in that they are all more or less the same length and alternate with one another.

These and other features led me to the genus Tetraneuris, consisting of nine species native to North America, often referred to collectively as bitterweeds. The name Tetraneuris means "four-nerved," and those four nerves are seen gracing each ray-flower corolla at http://www.backyardnature.net/n/13/130421tw.jpg.

In this part of the world we have two commonly occurring Tetraneuris species with very similar flowers, but different growth forms. Tetraneuris linearifolia is an annual herb with a branching stem, while Tetraneuris scaposa is a perennial with all its leaves forming a rosette at the base of long, slender, leafless flower-head stems arising from a woody base.

You've seen that our plants' flower heads arise on leafless peduncles issuing from leaf rosettes. I can tell you that if you finger the rosette bases you can feel the hard, knotty woodiness, which is convincingly not herbaceous. Therefore:

TETRANEURIS SCAPOSA, one of two species we can call Four-nerve Daisies. Other common names found for our species include Hymenoxys, Stemmy Four-nerve Daisy, Yellow Daisy and Bitterweed, though the last two names are applied to several other species as well. Our Tetraneuris scaposa occurs in the south-central US from Kansas and Colorado south through New Mexico and Texas deep into arid northern and central Mexico.

In Ethnobotany of The Zuñi Indians published by the Smithsonian Institution in 1908 and 09, I read that the Zuñi used to make an infusion of this species by soaking entire plants in cold water for several hours. This cured sore eyes and certain skin problems.

*****

SQUAREBUD DAISY
If Four-nerve Daisies are very commonly encountered, you can see a knee-high wildflower of which I've found only one example so far at http://www.backyardnature.net/n/13/130421t4.jpg.

At first glance this look like any number of yellow-blossomed Composite or Daisy-Family member, but even from several feet away you can see two unusual field marks for this species. First, notice that the disk flowers in the heads' centers are much larger than in most species. Also, check out what's shown on an opened head at http://www.backyardnature.net/n/13/130421t6.jpg.

The bases of the oversized, reddish-tinged disk flowers are partly enclosed within sharp-pointed, reddish-fringed bracts, or paleae. Most genera of composite flowers don't wrap their disk flowers in such bracts, so this is a good field mark.

However, you hardly need to see the oversized disk flowers wrapped in sharp bracts because of another feature that -- in terms of how composite blossoms are supposed to look -- is just amazing, and thus constitutes the best field mark of all: Each flower head wears below it a bowl-shaped "collar," as seen from below at http://www.backyardnature.net/n/13/130421t5.jpg.

Technically you would say that the outer four involucral bracts, or phyllaries, are expanded and grown together to form the collar. Such a feature is very unusual, though not unique to this species or genus.

Here we have what's sometimes called the Squarebud Daisy or Nerve-ray. It's TETRAGONATHECA TEXANA, one of only four species of the seldom heard-of genus found in North America, and endemic only to a few counties here in southwestern Texas and arid northeastern Mexico. The online Flora of North America describes its habitat as "Sandy soils, often with mesquite," so probably in the more arid scrub and desert south and west of here the species is more common than here.

The name Squarebud Daisy derives from the flower bud's appearance when the four bracts of its "collar" wrap around the immature blossom forming a four-cornered, boxy affair.

This is a very nice find, and in a world so populated with look-alike yellow, daisy-type flowers, it's great to have a species with a single field mark so effectively announcing its identity.

*****

MILKWEED VINE
Especially along trails and at woods edges you see slender, herbaceous vines with heart-shaped leaves arising from stems in pairs, and bearing unusual green, star-shaped, fingernail-sized flowers, as shown at http://www.backyardnature.net/n/13/130421as.jpg.

Up close, the little flower reveals arabesque patterns on its petals, seen at http://www.backyardnature.net/n/13/130421at.jpg.

The shiny dome in the flower's center is the gynostegium, composed of fused parts of the stamens and pistil. Gynostegia are highly evolved features typical of the former Milkweed Family, the Asclepiadaceae, which lately has been merged into the Dogbane Family, the Apocynaceae.

So, one common name for this handsome, delicate little vine is Green Milkweed Vine, though it's also known as the Netted Milkvine, Pearl Milkweed Vine, Net-vein Milkvine, and other names. It's MATELEA RETICULATA, endemic to west, central and southern Texas, and arid northeastern Mexico.

*****

FEATURED ESSAYS FROM THE PAST:

"99.97% and A Question," from the June 5, 2005 Newsletter, at http://www.backyardnature.net/n/p/050605.htm.

"Amoooooooooooor...," from the July 3, 2011 Newsletter, at http://www.backyardnature.net/n/p/110703.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