Issued from the valley of the Dry Frio River on the
southern slope of the Edwards Plateau, northern
Uvalde County, southwestern Texas, USA

July 14, 2013

Except on main highways, instead of bridges, here we have "low-water crossings," which means that roads simply dip into and out of normally dry streambeds -- arroyos, as they're called here -- or else cross on modest culverts with drainpipes through them. Sometimes water pools behind culverts creating communities of marsh and aquatic plants. Beside such a culvert a couple miles south of here a willow leans toward the road, a willowy branch of which is shown at http://www.backyardnature.net/n/13/130714sx.jpg.

That picture shows that nowadays the lower parts of young branches on mature female willows of this species bear capsule-type fruits. Some of the capsules already are splitting open, releasing seed-bearing fuzz into the wind, as shown at http://www.backyardnature.net/n/13/130714sz.jpg.

The seeds are so small that you might not notice them. You can see one embedded in fuzz in the picture's top, right corner at http://www.backyardnature.net/n/13/130714sw.jpg.

In most of eastern North America the most commonly encountered willow is the Black Willow, SALIX NIGRA, whose flowers and leaves we've admired at http://www.backyardnature.net/n/w/blackwil.htm.

However, the online Flora of North America describes 113 willow species for North America -- mainly occurring in northern states and provinces, and in the western mountains -- out of about 450 worldwide, so, which species is this? Despite looking just like Black Willows I've known back East, I had high hopes that our southwest Texas tree might be something new for me. You can see its leaves and slender, yellow-brown stem at http://www.backyardnature.net/n/13/130714sy.jpg.

Despite our edge-of-desert location, our roadside tree turns out to be another Black Willow. In fact, Black Willows extend well into Mexico, so you just have to admire this species' vigor and adaptiveness.

Field marks distinguishing Black Willows from other willow species include the long, narrow shape of the leaves and, especially, the fact that leaf undersurfaces are nearly the same color as leaf tops. Leaf undersurfaces of many willow species are noticeably paler than the tops. Speaking of the leaves, you might enjoy contemplating the elegant arabesques displayed by a willow leaf held against the sun at http://www.backyardnature.net/n/13/130714sv.jpg.


I'm amazed at how many rare and uncommon species I'm finding here on the Edwards Plateau's southern slope. For example, I was biking along the entry road a few miles south of the Center when suddenly there appeared the spectacularly flowering vine shown at http://www.backyardnature.net/n/13/130714cl.jpg.

The urn-shaped flowers' corolla-like parts are leathery, and if you look closely you see that actually the blossoms have no corolla at all. The red parts are modified calyxes. Typically calyxes are green and inconspicuously subtending colorful corollas, so here we have calyxes doing corolla service by attracting pollinators with their vibrant red color.

The sea-urchin-like fruit cluster below the blossoms is familiar to any gardener who grows clematis vines. A close-up of a fruit cluster showing the slender, very hairy, curved "beaks" of individual achene-type fruits is at http://www.backyardnature.net/n/13/130714cm.jpg.

A further field mark indicating that this is indeed a wild clematis is that of the compound leaves on their long, slender petioles, seen at http://www.backyardnature.net/n/13/130714cn.jpg.

So, this is a clematis vine, but which one is it of the 32 species described in the online Flora of North America?

It turns out that identifying our roadside vine was easy. It's CLEMATIS TEXENSIS, commonly known as the Scarlet or Texas Clematis. Here's how the Flora of North America characterizes the species: "Although widely cultivated because it is the only species of Clematis with truly red flowers, C. texensis is native only to the southeastern part of the Edwards Plateau, Texas."

The only Clematis with truly red flowers! And found in nature only here on the southern slope of the Edwards Plateau!

You might enjoy looking at a page showing cultivars developed from our  The cultivars bear such evocative names as 'Duchess of Albany,' 'Etoile Rose' and 'Gravetye Beauty.' The page is at http://www.taylorsclematis.co.uk/Clematis-texensis/.


A thigh-high wildflower member of the Composite or Sunflower Family heavily laden with panicles of pinkish-white flower heads leaned against a fence along the road, as shown at http://www.backyardnature.net/n/13/130714ac.jpg.

It looked like a member of the big genus Eupatorium, whose members commonly are called bonesets, thoroughworts, snakeroots or just eupatorium, and which are very common in the humid East. In fact, I almost ignored the fence plant because here in the Dry Frio Valley already I've seen so many new-to-me Composite Family members that I can't keep them all straight.

However, this was the first eupatorium-type wildflower I've seen here, so maybe it would turn out to be something special. I turned the bike around and settled down next to the plant to "do the botany." The first field mark noted was that the blossoms, unlike most eupatoriums, were pleasingly fragrant.

A side view of the flowering heads shows that the calyx-like involucre consists of overlapping, scale-like bracts, or phyllaries, like the eupatoriums, but textured differently from other eupatorium phyllaries I've seen, as shown at http://www.backyardnature.net/n/13/130714ad.jpg.

Eupatorium flower heads don't produce petal-like ray flowers; they're composed only of cylindrical disk flowers, the ones commonly forming "eyes" in most composite flowering heads. Well, some of our fence-plant's flowering heads almost look as if they have ray flowers. In the above picture, do you see those flat side-flowers curving away from the sides the way ray flowers might? This confused me, so a closer look was taken of an individual flower, shown at http://www.backyardnature.net/n/13/130714ae.jpg.

The vertical, orange structure in the picture's center consists of the flower's five long, slender, pollen-producing anthers fused along their edges to form a cylinder around the style. That's perfectly normal for the Composites, but what isn't normal is that the five corolla lobes are of different widths. There's a wide one and the rest are much more slender, meaning that the flower is not radially symmetrical, but rather bilaterally symmetrical, which is somewhat unusual for the Composite Family. More importantly, such blatantly bilaterally symmetrical flowers are not allowed in the Eupatorium "tribe" -- a subdivision of the Composite Family -- the Eupatorieae. Our fence plant is not a Eupatorium, and it isn't even closely related to it.

So, we have something unexpected here, so attention had to be paid to other field marks for later identification. Certain flowering heads already were fruiting. You can see some heads with their parachuted, cypsela-type fruits about to launch into the wind at http://www.backyardnature.net/n/13/130714af.jpg.

Most of the fence plant's stem leaves arose one per node -- they were "alternate." Their blades were attached directly to the stem in such a way that parts of the blade passed beyond the stem to form "ears," or basal lobes, as shown at http://www.backyardnature.net/n/13/130714ag.jpg.

Composite Family genera producing bilaterally symmetrical flowers are so relatively uncommon that our fence plant fairly quickly keyed out to this: ACOURTIA WRIGHTII, known in wildflower books as Brownfoot, and described by the Flora of North America as living on gravel, caliche, or sandy, loamy soils in open desert in much of northern Mexico, and in the US in Arizona, New Mexico, Utah and Texas. Our environment is a little lusher than "open desert," but we're on the eastern border of Brownfoot's distribution, so non-standard behavior can be excused.

The genus Acourtia embraces about 41 species in warm regions of Mexico, Central America and the southwestern US, with five species in the US. This is our second Acourtia species found here. The other, Acourtia runcinata, is more common. Though the flowers of our two Acourtia species are very similar, their body types differ radically. You've seen that Brownfoot produces a substantial branched stem. Our earlier Acourtia produced no stem at all, as you can confirm at http://www.backyardnature.net/n/h/acourtia.htm.

The Peterson Field Guide to Western Medicinal Plants and Herbs reports that Brownfoot's root has been used by the Navajo as a tea for women giving birth, to ease difficult labors and as a postpartum remedy.


While digging a trench through Glen Rose limestone for the nature center's pipes and wires I erected several nice rock piles. A few herbaceous plants, which most would call "weeds," came up through the rocks; you can see one at http://www.backyardnature.net/n/13/130714ch.jpg.

With the corolla so shallowly lobed that it more or less forms a disk, and with the leaves with their entire margins (un-toothed and un-lobed) looking very much like those of the local nightshades, I figured that this was a member of the big, important Nightshade Family, the Solanaceae. However, the five anthers of a nightshade are fused with one another by their margins to form a cylinder around the pistil's style, and they open by pores at their tips. The stamens of this plant didn't do that, as you can see at http://www.backyardnature.net/n/13/130714ci.jpg.

The anthers aren't at all fused, and they split lengthwise to release their pollen, like normal anthers, instead of having pores at their tips. So, what is this?

My first thought was that it might be what's variously called a ground cherry or tomatillo, genus Physalis, because ground cherries bear corollas more or less like this flower. However, ground cherry calyxes expand and inflate to form a kind of spherical bladder with the fruit suspended inside. Looking below the rock-pile flower, the calyx didn't seem to indicate any inclination at all to expand and inflate, as you can see at http://www.backyardnature.net/n/13/130714cj.jpg.

While looking beneath the flower, however, one couldn't fail to notice that this plant was thickly invested with short hairs.

As it turned out, this "weed" rising up among rocks stacked just a few weeks ago turned out to be a bit uncommon. It is indeed closely related to the ground cherries, but it differs from them by its calyx not forming a bladder around the fruit. It's CHAMAESARACHA EDWARDSIANA, listed in books as Edwards Plateau Five Eyes or Plateau False Nightshade. The common names and the "edwardsiana" in the binomial point to the fact that the species favors a few counties here on the southern slope of the Edwards Plateau in southwestern Texas, though it also occurs sporadically in New Mexico and arid northern Mexico. The genus Chamaesaracha comprises about nine species, all native to arid northern Mexico and the southwestern US. As a group they're often called five-eyes because of the five dark splotches normally marking their corollas.

At least four species of Chamaesaracha are known to occur in Uvalde County. Interestingly, this is one genus in which distinguishing the species is based less on characters of flower and fruit than on the types of hairs occurring on various parts of the body. To be Chamaesaracha edwardsiana our plant had to display the following field marks:

First, the stems had to be clothed in short, branched hairs, which they were, as was apparent below the dissecting scope, as shown at http://www.backyardnature.net/n/13/130714ck.jpg.

Second, the flower stems, or pedicels, had to be covered with hairs tipped with sticky glands, which they were, as shown at http://www.backyardnature.net/n/13/130714cg.jpg.

I don't recall having encountered before a group of plants in which the species so consistently differentiated themselves by having different kinds of hairs in different places. For example, if the glandular hairs hadn't been present, we would have had Chamaesaracha coronopus.

Also, when a "weed" grows up inside a pile of rocks, normally in the temperate zone it turns out to be an invasive of Eurasian origin. This is the first time I can recall a species of such limited occurrence quickly taking root in such a disturbed habitat. Maybe it evolved to pioneer vegetation in such places as where flashfloods pile up gravel.


Last October along a fence line where the mower couldn't get to I felt lucky to see a few especially striking wildflowers called Redspike Mexican Hats, shown at http://www.backyardnature.net/n/h/redspike.htm.

Since then I've seen photos of acres of Redspike Mexican Hats covering the valley floor in previous springs, though this spring was so droughty that only a few appeared. Three weeks ago it rained enough to cause these wildflowers to emerge and blanket certain low spots such as part of a basketball-court-size patch at http://www.backyardnature.net/n/13/130714ra.jpg.

Something I didn't notice in October but which is apparent with so many Redspike Mexican Hats flowering next to one another is that the color of the flowering heads' petal-like ray flowers -- the drooping, colorful parts of each flowering head -- range from entirely yellow to entirely dark brown, with most in-between.


In certain low, flat, marshy spots along the little Dry Frio River the vegetation gives way to grass-like herbage. Some of the plants are indeed grasses, but if you look closely you'll see many plant types, including sedges, umbrella-sedges, rushes, bulrushes, spikerushes and others.

Usually it's easy to say whether something is a sedge, umbrella-sedge, rush, or the rest, but figuring out which sedge or which rush can be hard. However, in our area, there's one Sedge-Family species so distinctive that when you see it you already know which species it is. In the landscape's visual cacophony of dark green marsh grasses and sedges it shows up as conspicuous, white, somewhat star-shaped blotches about the size of silver dollars, as shown as http://www.backyardnature.net/n/13/130714rh.jpg.

In that picture notice that immediately below the white flower clusters there are down-turned, white-based, leaf-like bracts nearly as long as the plants' stems. A close-up of the white star-shapes appears at http://www.backyardnature.net/n/13/130714ri.jpg.

This distinctive and unmistakable plant is RHYNCHOSPORA COLORATA, known by such common names as White Star Sedge, Starrush Whitetop, Star Rush, White-topped Sedge, and the like. Most plants known as sedges belong to the genus Caryx, so the name Whitetop Sedge is a little misleading, since this isn't a Caryx, but rather a Rhynchospora.

There's another white-topped star-sedge in the region, Rhynchospora nivea, but its white leaf bases are much narrower than the present species'.

Whitetop Sedge occurs in Mexico, the Caribbean area, Central America, northern South America, and the US Southeast mostly along the Coastal Plain. In the Yucatan we found this same species in marshy areas along the sea, especially in Sian Ka'an Biosphere Reserve.


Last November we profiled a carnivorous plant, a bladderwort, found along the Dry Frio River. I couldn't identify those plants to species level. This week I found another much larger population of bladderworts, and now I'm more comfortable suggesting a species name, though I'm still not 100% sure.

You can see a small part of the community, their yellow flowers atop slender, leafless stems, or peduncles, emerging from shallow water at http://www.backyardnature.net/n/13/130714ut.jpg.

A flower close-up showing a yellow "spur" jutting horizontally beneath the corolla's lower petal -- that petal bearing two bulges on its surface -- is at http://www.backyardnature.net/n/13/130714uu.jpg.

That picture shows the spur tip reaching the outer rim of the lower petal but not passing beyond it. Spurs on the bladderwort flowers found last November extended well beyond the lower petal's outer rim, and that was one feature that confused me.

Bladderworts entrap microscopic aquatic animals in their underwater bladders, where the animals are digested. You can see the bladders photographed last November at http://www.backyardnature.net/n/12/121104us.jpg.

The network of forking and reforking, submerged, bladder-bearing stems of this week's population was extensive, as you can see at http://www.backyardnature.net/n/13/130714uv.jpg.

Probably this is UTRICULARIA GIBBA, sometimes called the Humped or Floating Bladderwort. It's the most widespread of all bladderwort species -- all species of the genus Utricularia -- and is found on all continents except Antarctica. It's the only species listed for Uvalde County.

Last November I felt that those plants' long spurs poking from beneath the lower flower petals disqualified them from being this species, but now I've learned that Utricularia gibba varies a great deal across the world, including having flowers with especially long spurs.

Something new is that earlier this year the genome of Utricularia gibba was sequenced. One interesting tidbit of information resulting from that exercise is that now we know that the ancestors of bladderworts split from the ancestors of tomatoes 87 million years ago...

Utricularia gibba is considered to be easily grown in home aquaria -- even small cups or bowls. In fact, I placed a small stem segment from the bladderworts found last November in a jar of water, and now that jar is thick with bladder-bearing bladderwort stems.


Each morning I water the gardens beside the red cabin in the valley where I lived this winter, and each morning as sunlight slants in from the east it's a pleasure to see what the various crops are doing. For example, twining up the deer fence around the garden this week you could see what's shown at http://www.backyardnature.net/n/13/130714bm.jpg.

The trifoliate leaves on a vine and the distinctive flowers inform any gardener that this is a green bean vine. Pods ready to eat on a nearby bush variety can be seen at http://www.backyardnature.net/n/13/130714bn.jpg.

"Green bean" may not be what you call the plant in the picture, but that's what my family taught me to call the plants and their legumes back in rural western Kentucky. However, in other places and in other strata of society they might be called just plain beans, or common beans, string beans, snap beans, field beans, garden beans, haricot beans, pop beans, or something else. They're PHASEOLUS VULGARIS.

Most of the world's major crops originally were developed from wild species in Eurasia, but the ancestral Phaseolus vulgaris was native American, probably from Mexico and Guatemala. The species was introduced into the Old World by the Spaniards and Portuguese, and the bean is still much eaten in Latin America, where about 30% of world production takes place.

The genus to which green beans belong, Phaseolus, is home to about 50 bean species, all native to the Americas. At least three of those other Phaseolus species also have been developed horticulturally, among them the lima bean, Phaseolus limensis.

However, the green bean species, Phaseolus vulgaris, is the big one, and a surprising array of cultivars have been developed from it. The ancestral Phaseolus vulgaris is a vine, but "bush bean" cultivars are derived from it, as are kidney beans, navy beans and wax beans.

The Bean Family, the Fabaceae, is enormous -- by some estimates the third-largest plant family -- incorporating about 730 genera and over 19,400 species. The green bean genus Phaseolus distinguishes itself from its ±730 cogeners with these field marks: "papilionaceous" flowers composed of a top "banner" petal, two side petals called "wings," and two lower petals fused along their common margin to form a scoop-shaped structure, and referred to as the "keel"; leaves of three leaflets, with the middle one on a short stalk; the flowers' styles are "bearded" with hairs at their tips, and; the flowers' keels are coiled or spiraled.

That last field mark is the one to look for, though you may have to dissect a blossom to see it. First, take a look at a flower fresh from the plant shown above, at http://www.backyardnature.net/n/13/130714bo.jpg.

Notice how the side petals (wings) and the down-curved top petal (banner) conceal the two grown-together lower petals (the keel). In the picture just the base of the keel can be seen, curving upward to do its coiling and spiraling hidden from the watching world. Now look at what you see if you bend the wings and banner back, at http://www.backyardnature.net/n/13/130714bp.jpg.

The spiraling keel appears in the picture's top, right corner. At the bottom, left of the spiraling keel you can see several of the ten stamens' slender, anther-bearing filaments rising into the hollow keel.

Why would a flower produce a spiraling keel? In Mexico I asked that question about lima bean flowers, which do something similar. I reported then, "The pollinators I saw landed with their legs grasping the two bottom petals, the wings, so that most of the insect's weight rested on them. As the weight levered the wings down, some kind of inner linkage with the style caused the style's tip to thrust much farther from the keel, thus becoming much more likely to be dusted with pollen."

I suppose that something like that is going on here, but now my eyes are so bad I can't confirm such things.

Whatever the taxonomy, and whatever the story behind green bean's spiraling keels, nothing can take from the pleasure I have each morning when I see my green beans' bright flowers and bounty of bean pods, and the even greater pleasure of tasting the beans in my solar-cooked stews, or suspended inside great, steamy slabs of solar cornbread.


Though I'm already living in the nature center, it's not finished yet, nor is my solar cooker. However, like the nature center, there's enough of the cooker in place for it already to be doing its work, inelegant as it may be. You can see the cooker cooking my Thursday stew in an iron pot suspended above it at http://www.backyardnature.net/n/13/130714so.jpg.

Yellow squash, bell pepper, carrots, onion, garlic, chili pepper, Swiss chard, parsley -- from the garden -- plus brown rice, grits, lentils, some stale tortillas, and two eggs... Each day the recipe differs but it always smells good cooking, and tastes even better. You can see a typical stew at http://www.backyardnature.net/n/13/130714sp.jpg.

Later I'll finish covering the abandoned satellite dish's face with reflective aluminum sheeting, and it'll rest on rails instead of being propped into position with sticks and a chair. There'll be some manner of suspending the pot at the focal point other than by having it dangle from a bent Ashe Juniper limb held up by a tripod of other juniper stems.

However, I want to show you the cooker now, instead of when it's finished and better looking, to make the point that even with such a homely, roughly made, simple contraption some wonderful meals are being cooked free of charge, and not contributing to global warming. With this cooker I make cornbread that's even tastier than what I prepared this winter with a gas stove, and stews that as they cook bless the entire landscape with the smell of luscious bubbling stew.

You can see how the cooker works: Sunlight bounces from the parabolic dish's shiny surface to a certain focal point, exactly as radio signals did earlier from satellites in space. But instead of radio signals focusing at the focal point, the suspended pot receives concentrated sunlight.

You can see several other solar cookers I've built over the years at http://www.backyardnature.net/j/solardsh.htm.

Thanks to my neighbor Phred for helping me find the dish, transport it, and for supplying most of the tools and materials.



"On the Beauty of Relativism," from the July 17, 2005 Newsletter, at http://www.backyardnature.net/n/p/050717.htm.

"On Things Other than Medium Size" from the April 20, 2003 Newsletter, at http://www.backyardnature.net/n/p/030420.htm.


Best wishes to all Newsletter readers,


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