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  9, 2013

BARN SWALLOW EGGS
A couple of Newsletters ago we looked at the Barn Swallow nest being built beneath the eaves of the laundry shed adjacent to the cabin. Nowadays the female is incubating her eggs. One day this week when she took a break -- and breaks can be frequent during our afternoons when the temperature stands in the mid 90s (±35C) -- I snapped the picture shown at http://www.backyardnature.net/n/13/130609eg.jpg.

I read that the Barn Swallow's clutch size usually is 3-7 eggs, and you can see that our nest contains six. Eggs average about 0.7 inch long (1.9cm), and the incubation lasts for 12-17 days. The AllAboutBirds.org website describes the eggs as creamy or pinkish white, spotted with brown, lavender, and gray, which applies to our eggs exactly. That website also says that both male and female build the nest cup using mud, which they collect in their bills and often mix with grass stems to make pellets. They first construct a small dried-mud shelf to sit on, then build up the nest’s sides. The nest is first lined with grass, then feathers. Our Barn Swallows' nest thus appears to be exactly normal.

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PHOEBE NEST
It's interesting to compare the Barn Swallows' nest with that of another nest found this week perched atop a security lamp on the backyard porch of my friend Phred across the river. You can see the nest at http://www.backyardnature.net/n/13/130609ph.jpg.

It was easy to know which bird species the nest belonged to because as I approached the nest a pair of birds perched nearby began chipping and acting upset. You can see one of them at http://www.backyardnature.net/n/13/130609pi.jpg.

That's an Eastern Phoebe. Despite phoebes being here all winter, I was a little surprised to find these nesting on Phred's porch because distribution maps I've seen for the species indicate that they don't nest this far southwest. However, Michael Overton's "Birds of Uvalde County, Texas" checklist reports them as common here year round. We must be at the very most extreme southwestern point of their distribution. Say's Phoebes and Black Phoebes also occur here, which are western species, so that points to how remarkable our bird population is here.

Cornell Lab of Ornithology's Eastern Phoebe webpage says that only the female builds the nest, but she's often accompanied by the male, and that the nest is constructed of mud, moss, and leaves mixed with grass stems and animal hair. The nest on Phred's porch is made of lichen on a mud platform. Cornell continues by saying that nests may be situated on firm foundations, like ours, or they may adhere to a vertical wall using a surface irregularity. At first the female may need to hover in place as she forms a mud base to perch on. Nests can take 5–14 days to build and are about five inches across (13cm) when finished. The nest cup is 2.5 inches (6cm) across and two inches (5cm) deep.

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ARKANSAS YUCCA FLOWERING
Maybe the nicest surprise this week was when I was wandering the lower, deeply shaded slope of a limestone hill in a semi-open area of mostly Ashe Juniper and grass, and saw the prettily flowering yucca shown at http://www.backyardnature.net/n/13/130609yu.jpg.

It was wonderful how the white blossoms glowed so brightly in the shade, like detached globes of light hovering over the blades. A close-up of some flowers still dripping from a brief morning shower appears at http://www.backyardnature.net/n/13/130609yv.jpg.

A flower with some of its tepals folded back so you can see the male stamens and female pistil is at http://www.backyardnature.net/n/13/130609yw.jpg.

About 28 yucca species occur in North America and several conceivably might be found here, so I knew that here I'd have to "do the botany."

The main field marks of this yucca are largely visible without getting into the flower anatomy. First, as yucca species go, this was a smallish one, the top of the flowering head only about four feet high (1.2m). The tuft of leaves arises at or near the ground, and not on a distinct tree-like trunk, as with some species such as Joshua Trees, which are yuccas. Also, the flower cluster perches atop an especially short stem, or peduncle, with the lowest flowers' only a short distance above the leaf tips below them. Peduncles of many yucca species are much longer. Also, the flower cluster itself is not much branched. Only at the cluster base do flowers arise from branches off the central axis, or rachis. In the cluster's upper and middle part flowers arise directly from the rachis. Flower clusters of many yucca species are complex "panicles" while our cluster is mostly a "raceme." The plant's blades are also unusually slender and pliable.

These field marks and others identify our hill-growing yucca as the Arkansas Yucca, also called Softleaf Yucca. It's YUCCA ARKANSANA and it's found in a small, oblong distribution area stretching from southeastern Nebraska and southwestern Missouri through western Arkansas and eastern Oklahoma, to about here. We're located at its most extreme southwestern occurrence.

The flowers, fruits, seeds and stem pulp of most yuccas can be eaten, at least when boiled or roasted, and I suspect that that's the case with the Arkansas Yucca, too. However, Our Arkansas Yuccas are fairly uncommon here so I'd rather let them spread their seeds than to eat them.

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CATCLAW ACACIA FRUITS
In our March 24th Newsletter we looked at an acacia species known as Catclaw growing in thin soil atop our limestone hills here. The species was flowering then, as you can see at http://www.friocanyonnature.com/n/w/acacia-r.htm.

Now the white, spherical flower-heads we admired on those hilltop trees have given way to fairly distinctive looking fruits, shown at http://www.backyardnature.net/n/13/130609ac.jpg.

Since acacias are members of the big Bean Family, the pod-type fruits are legumes, and the seeds they contain can be called beans. You can see how the legumes are exceptionally flat but wide, somewhat curved, and bear conspicuous, wire-like sutures along each side where the legume ultimately will split. In the picture you can also see that each pod contains relatively few, fair-sized and widely spaced beans.

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SPINELESS, EDIBLE BACKYARD CACTUS IDENTIFIED
Just last week I showed you how I prepare for eating the spineless cactus growing behind the cabin. I remarked that this cactus didn't look like the famously edible and fairly spineless Nopal Cactus, or Indian Fig, we've seen so much of in Mexico, and that also it didn't seem to be a mere spineless race of the common pricklypear cactus in our area, the Texas Pricklypear. Last week I said I was eager to see the flowers so I could identify the big cactus, and now this week already the plant is ablaze with large, yellow blossoms, as shown at http://www.backyardnature.net/n/13/130609op.jpg.

The main field marks identifying this cactus, besides its spinelessness and yellow flowers, is the fact that this cactus doesn't sprawl on the ground like our abundant Texas Pricklypear, which seldom stands higher than three or four pads, yet neither does it possess a tree-like trunk, like some pricklypear species. Nopal Cactus, or Indian Fig, does produce a trunk. You might want to compare the above photo with pictures on our Nopal Cactus page at http://www.backyardnature.net/mexnat/nopal.htm.

On that page you'll see that Nopal's pads can grow much larger than the largest pads of our backyard species, and most have a different shape.

The backyard spineless cactus's blossoms are bright yellow on the day they open, then the second day they tend to remain closed, and turn pinkish, as shown at http://www.backyardnature.net/n/13/130609oq.jpg.

In that picture notice that the spherical stigma in the center of the many yellow anthers is a very pale green; stigma color in other species may be dark green, white, or other shades.

Another good field mark is that the older pads are a little silvery green, not the deep emerald green of many pricklypears. This silveriness is referred to as glaucescence, and you can see it at http://www.backyardnature.net/n/13/130609or.jpg.

Happily, the incomplete online Flora of North America has its Cactus Family finished, and there I could "key out" our cactus. It's OPUNTIA ELLISIANA, most commonly known as Spineless Pricklypear or Tiger Tongue. Some authorities regard Opuntia ellisiana as merely a spineless variant of Opuntia cacanapa of the Texas Big Bend area.

Whatever its "true identity," this spineless taxon doesn't seem to grow in the wild. I can't find anyone's theory on how the cultivar arose, but I have my own, especially because I'm in the process of reading the journal of Álvar Núñez Cabeza de Vaca, who in 1527 was shipwrecked on the Florida coast, then for eight years wandered through what is now the US and Mexico. His La Relación provides extraordinary accounts of America's indigenous people at that time, and their natural environment. Wikipedia's Cabeza de Vaca page is at http://en.wikipedia.org/wiki/Álvar_Núñez_Cabeza_de_Vaca.

Cabeza de Vaca wandered through this general area, often finding indigenous groups eating cactus fruits, and presumably they also ate the pads. I'd expect the indigenous people to have selectively bred pricklypear to get the spines off.

Whatever the history of Opuntia ellisiana, I'm tickled to know that that's who inhabits my backyard, and who in recent months has supplied so many tasty and nutritious meals. This is a wonderful cactus and I'll do my best to pass on pads to others who will plant them in their own backyards.

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OLD PLAINSMAN
Here and there in the Ashe Juniper and Texas Live Oak forests mantling limestone hills along the Dry Frio Valley, the trees thin out and sometimes even break into open grassy areas, which I think of as prairie patches. Sometimes these patches occur where soil is so thin and dry atop the limestone that it's understandable why grass grows there but not trees. Other times it's hard to say why the patches occur where they do.

Just as in the vast prairies to our north, these grassy areas are home to much more than grasses. A surprising variety of wildflowers and small shrubs grow there, except where local ranchers kill the Ashe Junipers and introduce livestock, and then of course the natural vegetation is replaced by mostly alien grasses and bare ground.

One wildflower now blossoming in our hillside prairie patches is shown at http://www.backyardnature.net/n/13/130609ha.jpg.

From a distance it looks just like many nondescript species topped with clumps of little white flowers, but when you begin "doing the botany" you find fascinating innovations that define the species, and unexpected prettiness.

The leaves have some personality, being deeply lobed, and the lobes themselves having lobes, as shown at http://www.backyardnature.net/n/13/130609hb.jpg.

On that leaf, notice how the bases of the main lobes extend onto the midrib creating green "wings" on both sides of the midrib. The leaf does have some character, but it's the flowers that capture our attention. Look how tiny white ones cluster into heads which themselves cluster into larger heads at http://www.backyardnature.net/n/13/130609hc.jpg.

Those familiar with wildflowers might find these flower cluster reminiscent of those of the Parsley Family, maybe like a cross between Queen Anne's Lace and garden Dill, both of which belong to the Parsley Family. However, even at the distance at which the above photograph was taken we can see that poking from each tiny, white flower there's a Y-shaped style, the base of which is surrounded by five anthers fused to one another along their sides forming a cylinder around the style base, so right there we know we have a member not of the Parsley Family but of the vast Composite or Daisy Family.

When diagnosing a member of that family one of the first things you must do is to look under one of the ultimate flower clusters to see what the calyx-like "involucre" looks like, so that's shown at http://www.backyardnature.net/n/13/130609hd.jpg.

In the Composite Family most involucres are composed of more green, scale-like "phyllaries" than is shown here. Normally there are so many phyllaries that they're arrayed in rows and overlap one another like roof shingles. Having so few phyllaries in a single row is a good field mark for this species.

However, there's something else that's almost amazing here, something you almost overlook if you're not paying attention. And that is that in this species the tips of the phyllaries, instead of coming to a point as in the vast majority of species, turn white and flair out, looking almost like flower petals. Very few composite flowers do that. In most species of the Composite Family, if there are petal-like items radiating away from a central "eye, those petal-like things are ray flowers surrounding the "eye" composed of disk flower. Some Composite species have only ray flowers and others only disk flowers. The species we're dealing with now produces only disk flowers, with no petal-like ray flowers, but the phyllaries, which in most species are green, are white, and function as petal-like ray flowers. This is field mark worth remembering.

Despite having noticed such a remarkable field mark, it's still worth breaking open a head to see what the disk flowers look like inside the head, and that's shown at http://www.backyardnature.net/n/13/130609he.jpg.

Here we see that no scale-like "paleae" separate the individual disk flower bases, and that there's not much of a pappus atop the future fruits, or cypselae. With higher magnification we'd see that the pappus consists of a dozen or so low, rounded scales.

What we have here is a wildflower graced with the evocative name Old Plainsman -- also called Woolly-White, Carolina Woollywhite, and White-bract Hymenopappus. The name Old Plainsman cues us to the fact that this plant is a distinctive species of dry, open prairies of the Great Plains north of us. It's HYMENOPAPPUS SCABIOSAEUS var. CORYMBOSUS, a biennial that spends its first season as a rosette of leaves hugging the ground.

Usually I don't mention variety names, but in this case the evolutionary fracturing of the species has progressed to the point that the two varieties are so near to becoming species that some experts have made them into their own species -- but not the online Flora of North America.

Our variety corymbosus occurs on clay and/or calcareous soil on limestone and in grasslands from Kansas south through here into Coahuila state in northeastern Mexico.

The variety scabiosaeus inhabits sandy soils in openings in pine and/or oak woodlands in the US Deep South and in the interior north to Indiana.

*****

DAYFLOWER
The cabin's owner pays a fellow to come mow the lawn. Happily, it's hard to get the mower beneath the Spineless Pricklypear in the backyard, so a veritable tiny prairie survives with more species diversity than all the rest of the mowed area. Nowadays in morning's first light, when the low sun's rays slant in just right, there's a spectacular burst of blueness there a little over an inch across (3cm) that's worth getting down on your knees in the dewy grass to look at closely. It's shown at http://www.backyardnature.net/n/13/130609co.jpg.

The structures and colors here are so surreal that even if you know your wildflowers you may not at first recognize this as a dayflower blossom. Dayflowers are members of the genus Commelina, of which about 170 species are recognized worldwide, with nine occurring in North America. Most species are tropical. Dayflowers are members of the Spiderwort Family, the Commelinaceae, and they're monocots, along with lilies, irises and grasses. A close-up of the strange structures in the blossom's center is at http://www.backyardnature.net/n/13/130609cq.jpg.

In the above photo you might guess that the items in the flower's center are the male stamens and female style, but, what's what? The two lower, pale violet things are vaguely similar to "normal" stamens consisting of slender filaments topped by baglike anthers that open to release pollen, and that's what they are. But the thing in the middle looking like a splayed banana peeling atop a stalk also is a stamen, jut a much modified one, maybe the brightness and largeness of its anther serving to attract pollinators, and its weird form providing pollinators a foothold. Dayflowers have five or six stamens, of which three are fertile -- they produce pollen -- and the rest are sterile, so from that we can derive that the other yellow objects at the right of the modified anther are sterile stamens, probably also helping to attract pollinators and give them a hold. Sterile stamens modified for such non-sexual service are called staminodia.

While looking at that picture, also notice at the picture's lower, right that there's a slender, white projection curving beneath the base of the filament of the large anther. That's the corolla's third petal. This petal's whiteness and very small size compared to the frequently larger and often blue petals of other dayflower species is an important field mark for what we have here.

When you look behind this surreal blossom you can begin believing that, instead of something from another world, we're dealing with just another nice wildflower. You can see how our dayflower's exotic explosion of raw blueness is attached to a regular plant body at http://www.backyardnature.net/n/13/130609cr.jpg.

The way the margins of the dayflower's grass-like leaves curve around the stem, join, and form cylindrical "sheaths" around the stem is typical of the Spiderwort Family to which this plant belongs. And it's a feature of dayflower blossoms that they arise from between folded-together halves of more or less heart-shaped "spathes," as our flower is doing. Inside each folded spathe reside developing flower buds and maturing fruits from flowers that already have opened and been pollinated. Flowers blossom only for a day -- in our case, only for three or four hours in the morning -- and that's why they're called dayflowers.

Our particular dayflower, COMMELINA ERECTA, often is referred to as the Whitemouth Dayflower, the name based on the tiny, white lower petal we saw earlier. Another name commonly used is Slender Dayflower. The species occurs widely across much of the southern US, from New Jersey to Wisconsin to New Mexico, then all through Mexico deep into Central America, in both temperate and tropical life zones. It's regarded as the most variable of dayflower species. On the Internet you can find pictures of flowers in which the white lower petal is very conspicuous, much in contrast to our almost hidden ones.

Dayflower leaves and stems generally are thought of as being soft and juicy enough to be edible, at least once they're boiled for maybe twenty minutes or fried, and the plants' young shoots, tips and flowers can be nibbled raw or put into salads. I find the Whitemouth Dayflower's vegetative parts a bit tougher than other species I've known, however, and the leaves thinner, so the species doesn't impress me as much of a candidate for the pot or skillet. Besides, it's too uncommon here, and too pretty, to eat except in emergency.

*****

BLUE-EYED GRASS
Yet a second delicate little wildflower producing surprising small bursts of blue along roads and in grassy areas in semi-open woods on the hills' lower slopes, only about five inches tall (13cm), is the one shown at http://www.backyardnature.net/n/13/130609si.jpg.

In that image notice how the blossom arises from two modified leaves, or bracts, shaped like scoops with their sides pressed together, and the upper bract's base fits into the lower one. This arrangement, which contributes to a slightly zigzagging stem, might remind you of how iris flowers do it, and that's appropriate, since this plant is a genuine wild member of the Iris Family.

A close-up of the 7/8ths-inch-across (22mm) blossom is shown at http://www.backyardnature.net/n/13/130609sj.jpg.

A shot of the same flower from below appears at http://www.backyardnature.net/n/13/130609sk.jpg.

Wildflower fanciers nearly everywhere in North America except the far North will recognize this commonly occurring and widely distributed wildflower as a kind of blue-eyed grass, genus Sisyrinchium. You can see that our flower has a yellow eye, not a blue one, and if it's a member of the Iris Family it's certainly not a grass, but that's how common names go.

Anyway, it's easy to recognize blue-eyed grasses, but saying which species of blue-eyed grass you have can be hard, since just in North America we have 37 species (about 80 worldwide), and details distinguishing them often are subtle. Fortunately the unfinished online Flora of North America has its Sisyrinchium section finished. There I could "key out" our plant as SISYRINCHIUM BIFORME, a species endemic to only a few counties along the Texas Gulf Coast and southwestern Louisiana, spottily inland in southern Texas (here), and adjacent Mexico. In other words, this was a nice find, a species of blue-eyed grass most Americans never get to see. The most commonly used English name for Sisyrinchium biforme seems to be Wiry Blue-eyed Grass, maybe because the stems are relatively slender and hard.

This species' field marks are so technical -- based on variations in features usually not found beyond the Iris Family -- that even readers of this Newsletter might get groggy hearing about them. However, good field marks for blue-eyed grasses in general include the manner by which the usually-blue flowers arise from those pairs of folded-together bracts, the fact that the leaves are flattish in cross-section (not folded, or V-shaped in cross-section, as among the irises), and that most species produce blossoms looking a lot like ours ours.

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SILVERLEAF NIGHTSHADE
One of the most commonly occurring, flowering roadside weeds here is the one shown http://www.backyardnature.net/n/13/130609sm.jpg.

It's worth taking a close look at the yellow, banana-like things in the blossom's center, as we do http://www.backyardnature.net/n/13/130609sn.jpg

You might guess that the bananas are the stamens' baglike, pollen-producing anthers. Normally when a flower's anthers are mature and ready to shed pollen they split down their sides releasing pollen from the resulting slits. The anthers in our photo don't do that. You can see tiny holes, or pores, at the anthers' tips, and that's where pollen exists the anthers.

In the plant world in general this is a novel way for an anther to shed its pollen. However, such anthers are the rule for plants known as the nightshades, and this is a nightshade. It's the Silverleaf Nightshade, also called White Horse-nettle, Prairie Berry and Trompillo. It's SOLANUM ELAEAGNIFOLIUM, a member of the huge, important Nightshade Family, the Solanaceae, in which we also find potatoes, peppers and tomatoes. In fact, tomato plants are in the same genus, Solanum; they're Solanum lycopersicum.

Interestingly, I read that Silverleaf Nightshade growing in humid regions don't normally produce spines or prickles, while those of arid regions are more commonly prickly. Our plants pictured above bore no prickles at all. However, their silvery leaves abundantly bore special kinds of whitish hairs known to be "stellate," or "star-like," as seen below our dissecting scope at http://www.backyardnature.net/n/13/130609sl.jpg.

The fruits are regarded as toxic. Still, the indigenous Pima people of North America used the berries as a vegetable rennet, rennet being used to curdle milk, as in making cheese. The Kiowa used the seeds together with brain tissue to tan leather. And since Silverleaf Nightshade produces such a deep root system and is able to survive very droughty conditions, and the 3/4-inch-wide flowers actually are quite pretty, some enlightened gardeners where water is scarce plant the species in their rock gardens.

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FEATURED ESSAYS FROM THE PAST:

"Not Economically Feasible," from the April 19, 2012 Newsletter, at http://www.backyardnature.net/n/p/090419.htm

"The Next Revolution," from the July 5, 2009 Newsletter, at http://www.backyardnature.net/n/p/090705.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