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

May 4, 2014

Last week we looked at an Ethmia Moth, large numbers of which spent their days gathered on the white walls of the building I was painting. This week the Ethmia Moths have almost disappeared, but another larger and much more colorful species has taken its place, at least near lights that stay on at night, and they're just as numerous as last week the Ethmia Moths were. You can see the bright new moth at http://www.backyardnature.net/n/14/140504mo.jpg.

Volunteer bug identifier in Ontario recognized this immediately as a kind of lichen moth, because she's seen them at her place. However, in our area there are two very similar lichen moth species, Hypoprepia fucosa, and Hypoprepia miniata, so which was this one?

After comparing our picture with many identified pictures on the Internet, it seems to me that ours is HYPOPREPIA MINIATA, the Scarlet-winged Lichen Moth. It appears to be a little broader than H. fucosa, plus the dark area on each of its exposed wings extends farther forward, well passing the orange, rounded thorax behind the head, which usually it doesn't in H. fucosa.

Lichen moth caterpillar larvae feed on tree lichens and blue-green algae growing on trees, fallen logs and rocks. Maybe because such food contains relatively little nutrition, the caterpillars might cannibalize smaller larvae.


A month ago we looked at the Jerusalem-thorn's exotic-looking leaves as they unfurled. Our page showing them is at http://www.backyardnature.net/n/w/jerthorn.htm.

Nowadays the Jerusalem-thorn's leaves are fully deployed, plus many branch-tips bear pretty bunches of yellow flowers, which can be admired at http://www.backyardnature.net/n/14/140504pk.jpg.

The individual flowers, about an inch across (2.5cm), are worth looking closely at, which you can do at http://www.backyardnature.net/n/14/140504pl.jpg.

Jerusalem-thorns are members of the Bean Family, but you can see that this flower doesn't display the pronounced bilateral symmetry of the typical bean-vine flower. Bilaterally symmetrical things have one side that is a mirror image of the other, but there's only one way the mirror can cut across the object. Our flower isn't quite "radially symmetrical," like a rose, but it almost is. This half-hearted bilateral symmetry is typical of the subfamily Jerusalem-thorn belongs to, the Caesalpinioideae -- cassias and sennas being the best-known members -- in which flowers are only slightly bilaterally symmetrical.

Paying special attention to its asymmetries, you can see that our flower is a little taller than wide. Also, only the topmost petal bears reddish spots at the bottom of its blade. The blossom's most conspicuous asymmetry, however, is with its stamens. Notice the large ones with plump, pink anthers at the bottom of the stamen cluster, with much smaller, browner anthers above, and some stamens are on stems, or filaments, longer than others.


Biking Uvalde's back streets is a pleasure if only to see the ornamental plants growing in people's yards. A small part of a ten-ft-high (2m), slender-branched bush that nowadays is one of the prettiest and most conspicuous flowering plants, usually growing amidst tall, dense hedges along streets, is shown at http://www.backyardnature.net/n/14/140504pu.jpg.

In that picture, the thick trunk behind the flowers belongs to an old liveoak; the flowering bush's trunk and branches are slender. A flower close-up is shown at http://www.backyardnature.net/n/14/140504pv.jpg.

In Mexico we've seen this plant a lot, but I was surprised to find it growing so well this far north. The large, red corollas arising from thick, leathery, red calyxes, along with those glossy, semi-leathery, simple leaves can only mean "Pomegranate," PUNICA GRANATUM.

However, flowers of Mexico's pomegranates normally display swollen bases below their calyxes, where the future pomegranate fruit will develop. These flowers' bases aren't at all swollen, so I'm guessing that they're a special ornamental "flowering pomegranate," of which the Web assures us that many cultivars exist, including "double-flowered" ones with blossoms looking like red carnations, and white-flowered and variegated ones. The different flowering varieties produce fruits of various sizes smaller than their fruiting trees, sometimes practically not developing fruits at all.

Certainly fruit-producing Pomegranate trees can be grown in our area. The Texas AgriLife Research and Extension Center at Uvalde disseminates a fruit-producing Pomegranate called "Spanish Sweet." Pomegranates are described as fruiting well in USDA Plant Hardiness Zones 8 to 10, and we're in Zone 8. It's iffy for colder Zone 7.

Pomegranate trees are members of the same family to which also belong Crape-Myrtle and Loosestrife, the Lythraceae. One field mark of that mostly tropical American family is that its species produce flowers in which the stamens, instead of arising from beneath the ovary the way seen in many flowers, are attached directly to the inner walls of the leathery calyx, as shown at http://www.backyardnature.net/n/14/140504pw.jpg.

In that picture also you can see that there's hardly any swollen ovary beneath the flower, so you'd not expect this flower to produce much of a fruit, if any fruit at all.



Rooting in mud beside a pond in Cooks Slough Nature Park on Uvalde's south side, nowadays a robust grass is issuing flowering heads on stems about eight ft high (2.5m), as seen at http://www.backyardnature.net/n/14/140504tr.jpg.  

The flowering heads, or inflorescences, consist of two or three slender flower spikes, as shown at http://www.backyardnature.net/n/14/140504ts.jpg.

Something interesting to notice in that picture is that each spike's upper 5/6ths or so of length looks different from its lower 1/6th. The lower flowers are green, thick, and lacking the purple trashy things covering the upper part of the spike. You can see what the trashy things are in a closer look at some upper flowers at http://www.backyardnature.net/n/14/140504tt.jpg.

Here we can see that the dark, chaffy items messily covering the upper 5/6ths of the spikes are anthers, from which pollen is released in pores that are clearly visible on the ends opposite where the anthers attach to their threadlike filaments. Since the anthers dangle upside-down on their filaments, pollen grains tumble from the the anthers' "tops," which hang downward. The picture shows unisexual male flowers. This means that the spike's upper 5/6ths will produce no seedlike grains. Once the male flowers have done their pollinating job, their part of the spike will fall away. Now look at the very different female flowers occupying the spikes' lower regions at http://www.backyardnature.net/n/14/140504tu.jpg.

The fuzzy, threadlike things are stigmas designed to catch pollen grains. The tear-shaped items below the stigmas are the female flowers, their ovaries protected beneath hard, shiny, green scales, or glumes. Notice the unusual nature of the "stem," or rachis, to which the individual flowers are attached. Each female flower fits into a hollow indenting the rachis. Since the hollow is deep below and shallow above, the rachis itself narrows where each flower arises, but thickens toward each flower's top, but then quickly thickens again where the next higher flower is affixed. This gives the rachis a zigzag form. When the female flower matures -- when the ovary becomes a grain-type fruit -- the spike breaks immediately below each female flower, and the section of that spike falls away carrying the mature flower with its grain, forming a short, cylindrical, tin-can-looking object people call "seeds," though they're mostly stem and scales. This is a very unusual structure for a grass to produce.

This handsome and amazing grass is TRIPSACUM DACTYLOIDES, native to the warmer parts of the Americas, from the US southeastern and south-central states (as far north as Iowa and New Jersey) south to northern South America. In the US normally it's called Eastern Gamagrass, not to be confused with grama grass, of the genus Bouteloua.

With its unisexual flowers arranged in spikes at the top of the plant, with male flowers above and females below, you might think of another amazing grass, called corn in the US and maize elsewhere. Gamagrass is somewhat related to corn

Eastern Gamagrass is very variable, and its many types have adapted to a wide variety of habitats, from muddy shores like where we found ours, to rocky outcrops and openings in forests. In some places the plant hardly gets knee high but in others it can reach 13ft tall (4m). In South America it's grown for livestock forage but in the US mainly it's grown as an ornamental grass that's easy to grow.

Certain birds eat the grains, and the grass' extensive root system keep soil from washing away.


Among the ponds and Mesquite-dominated scrub in Cooks Slough Nature Park on Uvalde's south side, one of the largest, most robustly branching thistles I've ever seen stood about six feet high (2m) beside a trail. It's shown at http://www.backyardnature.net/n/14/140504sb.jpg.

Here in cow country we have lots of thistles, since cattle eat most everything else, leaving the thistles standing and reproducing. Though some folks call almost any spiny herb a thistle, the name thistle is more conservatively reserved for species in the Composite or Sunflower Family subgroup, or "tribe," the Cynareae. Within the Cynareae, the best known genera are Carduus and Cirsium.

However, our Cooks Slough thistle isn't one of those, though it is a member of the tribe Cynareae. If you look closely at our slough plant, you see features you may not expect of a typical thistle. For example, the plant's spiny-margined leaves are up to two feet long (60cm) and, even more unusual, they're handsomely mottled, or variegated, as shown at http://www.backyardnature.net/n/14/140504sc.jpg.

The flowering heads also are unusual because the leafy scales, or phyllaries, forming the green, bowl-like involucre below the many violet-colored florets bear spines much larger and more threatening than is seen on normal thistles, as you can see at http://www.backyardnature.net/n/14/140504sd.jpg.

Our slough thistle has been flowering for some time, so already its old heads are opening to release parachute-equipped fruits into the wind, shown at http://www.backyardnature.net/n/14/140504se.jpg.

We'll see below why it's worthwhile to pay special attention to the seed-like, cypsela-type fruits. A close-up of a cypsela with its parachute of white hairs is at http://www.backyardnature.net/n/14/140504sf.jpg.

With so many striking and unusual features, it's easy to identify this thistle as what in North America most often is called the Milk Thistle. It's SILYBUM MARIANUM, originally from the Mediterranean region of southern Europe, but now invading disturbed land throughout much of the world, including spottily throughout most of the US, but mostly in the warmer states. Though the Milk Thistle has a long history of providing food and medicine, and many regard it as pretty enough to plant as an ornamental, in Texas most folks think of it as a noxious weed -- less because of its spininess than because it causes nitrate poisoning in cattle and sheep who eat it.

In Europe during the 1500s it was well regarded as an edible herb, its young shoots being boiled and eaten like cabbage and its young leaves added to salads. In the past, even the big, spiny phyllaries surrounding the base of its flowering heads were boiled and eaten like artichoke bracts. Its stems were peeled, soaked overnight to remove the bitterness, and stewed. Its seeds were roasted, ground and used as a coffee substitute.

It's the seeds receiving most attention nowadays, because in the field of herbal medicine extracts from the seeds are much used, mostly for liver and gallbladder ailments but also to cure a wide range of problems, from hepatitis to tumors, and obsessive-compulsive disorder. Just Google the keywords "Silybum medicinal" for links to hundreds of sites praising the Milk Thistle's virtues, and selling medicines based on it.


A couple of Newsletters ago we looked at the Red Pricklypoppy, easy to recognize since it produces the only dark-lavender-colored pricklypoppy flowers in our area. You can review that pretty species at http://www.backyardnature.net/n/h/redprick.htm.

The plant featured on that page was one of few among hundreds of other plants that were very similar, except that they bore white flowers, with many white flowers slightly rosy-tinged. During that first visit I identified only the Red Pricklypoppy, saving the white-flowered ones for later. This week I returned to the same spot in Cooks Slough on Uvalde's south side, paying attention now to the white-flowered plants. You can see a typical white-flowered plant along a trail through scrubby Mesquite at http://www.backyardnature.net/n/14/140504pp.jpg.

A flower close-up showing petals slightly tinged with pink and an "eye" of purplish stamens and stigmas is at http://www.backyardnature.net/n/14/140504pq.jpg.

Another view showing the flower from the side, and a spiny flower bud with its spines bent slightly upward just like the Red Pricklypoppy's, is at http://www.backyardnature.net/n/14/140504ps.jpg.

Leaves and stems on these white-flowered plants were practically identical to those of nearby Red Pricklypoppies, as you can see at http://www.backyardnature.net/n/14/140504pr.jpg.

Well, probably by now you are guessing that these white-flowered plants also are Red Pricklypoppies, despite their white flowers. And despite the lack of blossoms that were neither as darkly "red" as the Red's, or brightly white as those in our photos. Well, the Flora of North America plainly describes the Red Pricklypoppy's petals as "white or lavender," so it should not have taken me so long to realize that the two flower types were all the same thing. One reason for my slowness was that on the Internet the vast majority of Red Pricklypoppies are depicted with dark lavender flowers, probably because the more vividly colored plants are easier to identify as Red Pricklypoppies.

In our area we have other white-flowered pricklypoppy species, such as the Texas Prickly Poppy so abundant in the Upper Dry Frio Valley, profiled at http://www.backyardnature.net/n/h/prickpop.htm.

The easiest way to distinguish a white-flowered Red Pricklypoppy from one of those other white-flowered species is that even in the Red Pricklypoppy's white flowers, the stamens' stem-like filaments are purplish, while filaments of other white-flowered species in our area are lemon yellow.


Neighbor Phred pointed out something interesting on the roof of the building I was painting. You can see it at http://www.backyardnature.net/n/14/140504zn.jpg.

The slanting roof below the old galvanized-steel ventilator is lighter than the surrounding roof area. Phred said that zinc bled from the ventilator metal, killing moss growing on and darkening the roof. When we looked around at other roofs in the area, similar effects were seen. I figured that in our arid climate maybe the roof darkening was more likely caused by lichen and cyanobacteria than moss, but otherwise it was clear that something was bleaching the roof below the ventilator.

It turns out that a sizable industry is practiced by folks eager for a good fee to nail "zinc strips" on roofs in order to keep the roofs from darkening from the growth of "moss, algae and lichens." Moreover, many of the industry's websites show pictures like ours, and some pictures definitely portray moss communities being impacted, such as one on an Oregon State University page at http://bryophytes.science.oregonstate.edu/page24.htm.

That page claims that zinc strips and galvanized flashing are apparently relatively safe and inexpensive ways to "... effectively kill or retard the growth of mosses and fungi and appear to have effect up to 15 feet below the zinc flashing along the length of the flashing." Most brands of zinc strips are effective for about a year, while the effects of galvanized flashing can persist for decades.

In school we learn that zinc is an essential nutrient for living things. In human bodies, zinc is the second most abundant trace mineral after iron, and is known to be a key mineral for cell and tissue renewal. It's also important for blood clotting, sperm production and the formation of testosterone. It acts as an antioxidant, and helps to maintain proper vision and a normal sense of taste and smell.

However, in humans, too much zinc can result in conditions known as the "zinc shakes" or "zinc chills," involving nausea, vomiting, cramps and diarrhea. People have died from exposure to zinc chloride fumes, and livestock have died from inhaling air contaminated with lead and zinc. I find no source describing a specific biochemical mechanism causing zinc toxicity, though one source says that zinc binds to proteins and organic acids in plants. Other studies find that a certain concentration of zinc might harm one moss species, but enhance growth in another.

So, with this mishmash of information in mind, now every time I see that roof with its ventilator and wiped-out biotic community, it sets off a whole series of thoughts.

For one thing, I wonder: If a simple roof ventilator can so decisively impact the ecology around it, what else around us might be affecting our health, including the way we think and feel? What are the deteriorating underground pipes carrying our water to us adding to our water, or the slowly dissolving plastic containers our store-bought water comes in? What about city air, and the chemicals governments spray us with to kill weeds, or keep down mosquitoes?

Also, I wonder: Who said that a roof darkened with moss or lichen is ugly or that the roof's natural biotic community needs to be destroyed? What's wrong with the notion that a roof growing dark with lichen and moss looks and feels more "homey," settled and at ease with the world around it? Who gets to establish the norms for social ethics and for esthetics in general?

Is this slightly off-kilter feeling I'm experiencing right now caused by my hypoglycemia, or the fillings in my teeth that have been eroding away since the 1960s and 1970s? Or the chemicals they used to flush the well dug here a while back, now with residues in my drinkwater?

Each time I see how that old roof ventilator has killed things around it, it gives me the creeps.



"Shadowy Forest" from the April 27, 2003 Newsletter, at http://www.backyardnature.net/n/p/030427x.htm

"Primitive Magnolias" from the April 27, 2003 Newsletter, at http://www.backyardnature.net/n/p/030427.htm


Best wishes to all Newsletter readers,


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