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

April 20, 2014

Last weekend my college friend Jarvis visited from North Carolina. He's a retired college ecology prof so I figured he'd enjoy visiting Cooks Slough Sanctuary and Nature Park on Uvalde's south side, which we did. A resting spot in the sanctuary next to a pond was called Whistling Duck Overlook and I had to ask Jarvis what a whistling duck was. He said that that's what field guides have begun calling what I learned to name tree ducks -- ducks of the genus Dendrocygna. Before long a few whistling ducks with their black underparts and large, white wing streaks turned up out on the waters, mixed with many Northern Shovelers. Also, we came upon the pretty gathering shown at http://www.backyardnature.net/n/14/140420wd.jpg.

Those are Black-bellied Whistling-ducks, DENDROCYGNA AUTUMNALIS, which surprises me because the distribution map in my old field guide shows this tropical bird as present in the US only in the southernmost tip of Texas and thus not this far north. But Jarvis said that for some years the species has been expanding its distribution northward at a fairly fast rate. Now I see that new distribution maps show Black-bellies as summer breeders as far up the Mississippi River as Memphis, Tennessee, and as permanent residents in Florida, Louisiana and much of eastern and southern Texas. In tropical America they occur as far south as northern Argentina.

Cornell's "All About Birds" website explains the Black-bellied Whistling-duck's expansion northward in terms of the ducks' adapting easily to human-altered habitats. They feed on waste grain in agricultural fields, and often at night forage along the banks of shallow, man-made ponds, even those in golf courses, city parks, and sometimes they even turn up in schoolyards. As they fly between feeding areas and roosting sites, instead of quacking they emit distinctive, high-pitched whistles. As in our picture, they tend to perch in trees over water. They nest in cavities, including nest boxes.

It's gratifying to see native birds adapting to human disruptions, especially when the species is as handsome as this one.


A damselfly alighted on a limestone boulder beside the trickling Dry Frio River, shown at http://www.backyardnature.net/n/14/140420df.jpg.

I wasn't sure this one could be identified because Michael Overton's "Odonates of Uvalde County, Texas Field Checklist" lists 25 damselfly species, and most of them are slender with a blue-tipped abdomen, like this one. However, the checklist enabled me to do Google image searches on each of the 25 species, comparing them with our picture.

The first thing that became apparent was that our damselfly was a member of the largest genus on the checklist, genus Argia, a group of damselflies often known as dancers. Ten Argia species were listed, all at first glance very similar to the one in our photo.

However, there were indeed slight differences. For example, the Blue-fronted Dancer's long abdomen was ringed with very distinct, narrow, bright-blue bands, while the blue bands on the abdomen of ours were darker and relatively broader. The Comanche Dancer's blue bands were much thicker, limiting the black between them to bands much narrower than our damselfly's. On and on the comparisons went, each time slight differences turning up, until one species was nearly a perfect match: the Kiowa Dancer, ARGIA IMMUNDA. Happily, volunteer identifier Bea in Ontario independently came up with the same name.

Kiowa Dancers are mostly a tropical species, commonly occurring along streams and rivers from Belize up through Mexico, into the southwestern US from California east to Texas, and north to South Dakota.

The blue abdominal bands on most males pictured on the Internet are more brightly blue than on our individual, while females are dingier, their abdomens ringed more with blue-gray or plain gray than ours. However, our individual matches some identified as young males.


Also at Cook's Slough on Uvalde's south side a butterfly new to me was spotted perching atop a pile of raccoon poop in the middle of the trail. You can see the numerous "eyes" on the butterfly's lower wing surfaces at http://www.backyardnature.net/n/14/140420as.jpg.

Volunteer butterfly identifier Bea in wintry Ontario was tickled to have a butterfly to work with, and especially happy that it was a species found only in a small corner of North America, from Southern Arizona east to South Texas, but mostly in the northern half of Mexico.

It was the Empress Leilia, ASTEROCAMPA LEILIA, and it was appropriate that we found her atop a pile of raccoon poop because adults of this species feeds mainly on plant sap and animal dung, only occasionally taking flower nectar. Its habitat is described as "thorn scrub, washes, canyons, streamsides."

Empress Leilia caterpillars feed on the Desert Hackberry, Celtis pallida. I've not seen Desert Hackberries during my year and a half in the upper Dry Frio Valley, but at Uvalde we were 781 feet lower in elevation than at Juniper House, and in an entirely different biogeographic province -- on the Coastal Plain, instead of on the southern slope of the Edwards Plateau. And in the scrub forest around Uvalde, Desert Hackberries are common. The genus to which the Empress Leilia belongs, Asterocampa, holds species often known as hackberry butterflies because their caterpillars feed on hackberry leaves. Male Empress Leilia butterflies perch most of the day watching for females, who lay eggs in clusters of 10-15 atop Desert Hackberry leaves

The name Empress Leilia doesn't seem especially appropriate for a butterfly occurring mostly in arid, Spanish speaking territory. I understand that the name "Leilia" is derived from the Arabic "leila," referring to night or "dark beauty," or the Persian "leila," meaning "dark-haired."


The Desert Hackberry, sometimes called Spiny Hackerry, CELTIS PALLIDA, is common in the scrubby forest around Uvalde. A typically zigzagging branch of one about shoulder high, bearing new leaves and flowers, is shown at http://www.backyardnature.net/n/14/140420ce.jpg.

Flowers in the Elm Family, to which hackberries belong, are either unisexual or "hermaphroditic" -- hermaphroditic ones possessing both male and female parts. Hackberry species normally bear both unisexual and hermaphroditic flowers on the same tree, though sometimes the trees are functionally one sex or another. In the above picture the yellowish-green blossoms scattered along the twigs are male flowers consisting of little more than bundles of pollen-producing stamens. However, here and there female flowers do occur, easy to identify because among small and apparently useless stamens rise plump ovaries looking like tiny, green eggs, as seen at http://www.backyardnature.net/n/14/140420cf.jpg.

In that picture the fuzzy item atop the ovary is the two-lobed style with hairy stigmatic zones for catching pollen from male hackberry flowers. Those stubby, curved, banana-shaped things below the ovary are vestigial stamens. You can see that this flower bears no corolla, and that's a feature of the entire Elm Famil. By fall, the ovary will have developed into a sweet, edible, yellow-orange fruit, a drupe, relished by birds.

In fact, the fruits, along with the densely entangling spiny branches, cause Desert Hackberry to be extremely valuable as wildlife food and cover. It's also useful for erosion control, and because of its dense habit can be useful as a landscape screen or informal hedge.

Desert Hackberry leaves don't grow much larger than what's shown above, so relative to other hackberry species Desert Hackberry leaves are exceptionally small. Though the limb in the picture is spineless, Desert Hackberry often bears slender spines. The side branches of the branch in our picture are spinelike, or "spinescent" -- like stout spines bearing leaves and flowers.

Desert Hackberry occurs throughout tropical America from northern Argentina north to southern Texas, New Mexico, Arizona, and Florida, It's likely to show up in grasslands, brushlands and thickets wherever there's gravelly, well-drained, sandy soil, as in deserts, canyons, washes, foothills, washes and the like.


In early March, along the tiny Leona River passing through Uvalde, we saw Mexican Ashes flowering as their leaves emerged. Our Mexican Ash page is at http://www.backyardnature.net/n/w/mex-ash.htm.

Now that leaves on Mexican Ashes are fully expanded, some branches are heavily laden with ash fruits, as shown at http://www.backyardnature.net/n/14/140420fx.jpg.

Ash fruits are achene-type "samaras," which are one-seeded, winged fruits that don't split open at maturity.


Neighbor Phred had told me that in the local cobblestone fields of the floodplain of the little Dry Frio River there used to be little cacti shaped like bunches of green jalapeƱo peppers joined at their stems. With their rounded bottoms pointing outward, each bottom was equipped with numerous stiff spines. Cactus conoisseurs will recognize that we're referring to a kind of nipple cactus of the genus Mammillaria.

So far I'd not seen any Mammillarias, and I'd figured that local people had dug them all up for potting, or maybe the occasional attempts to exterminate our Ashe Junipers had squashed or burnt them all. However, this week a small cluster turned up on the cobblestone floodplain, shown at http://www.backyardnature.net/n/14/140420mm.jpg.

The population was about the size of a saucer. In the picture there's an older body on the right, a younger one at the left, and quite young ones emerging with pale spines in the center, below and above. A close-up of the spines atop a "nipple" is at http://www.backyardnature.net/n/14/140420mn.jpg.

In that picture, notice that each spine cluster consists of a single thick-based spine emerging from the center of a cottony zone at the nipples top, surrounded by about a dozen smaller, outward-radiating spines.

Mammillaria is an important cactus genus, containing about 164 species, all restricted to Mexico, Central America, the West Indies and the southwestern US. The Flora of North America describes 14 species in the US. Important field marks leading us to the identity of this one include the following:

Books call this the Little Nipple Cactus. It's MAMMILLARIA HEYDERI. It's the most widely spread Mammillaria species in the US Southwest, occurring from southern Arizona and New Mexico through western and southern Texas, plus the arid northern half of Mexico. On the Internet it's mainly documented as a potted plant. When they're potted and taken care of they grow larger than ours, with many more "nipples," and more regularly spaced spine clusters. Gardeners consider Little Nipple Cactuses as one of the most cold-hardy of Mammillaria species.


At Cook's Slough on Uvalde's south side, along a trail through the low, scrubby forest adjacent to the ponds, hundreds of knee-high prickly poppies bore large, white flowers, but occasionally one or two darkly rose-colored blossoms -- also prickly poppy flowers -- appeared among the many white heads. You can see a couple of rosy ones next to a more common white blossom at http://www.backyardnature.net/n/14/140420pp.jpg.

Though the rosy flowers are slightly smaller than the white one, the blossoms' structure is very similar, as are the leaves. Some white flowers were slightly tinged with a reddish hue, so the question arose: Were we seeing just one species with flowers ranging in color from white to rose, or were two distinct prickly poppy species mingling along the road?

To determine the matter, first a rosy blossom was looked at closely, revealing a prettiness of many dark stamens issuing from the base of a thick, stumpy ovary topped with a blunt, fuzzy, four-lobed stigma, as shown at http://www.backyardnature.net/n/14/140420pq.jpg.

Below the 2.5-inch-wide (7cm) blossom, the rosy petals were subtended not by a typical, green, cup-like calyx, but rather by a spine-bearing, modified leaf, or bract. In the Poppy Family, to which prickly poppies belong, normally the calyx's sepals fall off as the flower matures, leaving bracts to do sepal duty. You can see all this at http://www.backyardnature.net/n/14/140420pr.jpg.

In that picture, the two spiny, pod-like items on stems beside the blossom are not fruits but rather flower buds. Each bud's spiny covering is formed by two sepals not yet split from one another and not yet fallen off.

A leaf of the plant showing its base partly growing around the stem, with spiny margins but no spines arising from veins on the blade's upper surface, and lobes with sinuses cutting more than 4/5ths of the way to the midvein is shown at http://www.backyardnature.net/n/14/140420ps.jpg.

Happily, the online Flora of North America has its prickly poppy section finished, so in the prickly poppy genus key all the above field marks inexorably direct us to the Red Prickly Poppy, also known as Rose Prickly Poppy, ARGEMONE SANGUINEA.

Red Prickly Poppies are mostly found in arid northern Mexico, but their distribution area extends into the US here in southern Texas. In our area the species is described as occupying open areas, overgrazed fields, and weedy areas, but not forming solid patches like white-flowered species can. Ranchers say that livestock won't eat Red Prickly Poppies, even at the end of a long dry season when most other plants have been consumed.

Identifying Red Prickly Poppy isn't a simple matter of noticing that the plant's flowers are rosy instead of the more commonly encountered white or yellow blossoms. Red Prickly Poppy can produce white flowers, and some white-flowered species can develop reddish flowers. To get the name of a prickly poppy, flower color is important, but plant structure and form are determinative.


In mud beside a small lagoon at Cooks Slough Sanctuary and Nature Park on Uvalde's south side there was a dense, mat-forming stand of spikerushes, a small part of which is shown at http://www.backyardnature.net/n/14/140420el.jpg.

Spikerushes are members of the Sedge Family, the Cyperaceae, and the genus Eleocharis. They differ from other members of the family by producing flowers packed closely together into short, cylindrical spikes at the tips of slender, leafless stems, which are round in cross-section, not three-sided like some members of the family. A view of this spikerush's wiry,lower stems is at http://www.backyardnature.net/n/14/140420en.jpg.

Spikerushes occur worldwide, and the Flora of North America treats 67 species for North America. So, which species is this?

We've already identified two spikerush species in our area. Along the Dry Frio there's the very small Eleocharis geniculata shown at http://www.backyardnature.net/n/h/eleochar.htm, and the much larger and less common Eleocharis cellulosa, shown at http://www.backyardnature.net/n/h/gc-spike.htm. This species from the Coastal Plain is different from those, and here are some of its distinguishing field marks:

First, its height is intermediate the two above species, about 15 inches high (40cm). Also, for its height, its stems are extremely slender and stiff, and its more-or-less egg-shaped spikes are very short, adding only a tiny bit of extra height to the plant. A close-up of a spike shows other noteworthy features at http://www.backyardnature.net/n/14/140420em.jpg.

In that spike the flowers -- one flower arising behind each fingernail-like scale -- are at different stages of development. The top, least mature ones each issue three style branches from behind their scale, these deployed to catch pollen for the ovary behind the scale. If you look closely you can see that the lower the styles occur on the spike, the browner and more dried-out looking they are. However, flowers in the spike's center are just beginning to issue pollen-producing, yellow anthers, which dangle on their filaments, but even they, on the lowest flowers, are beginning to darken, dry out and shrivel. When the spike is mature, all style branches and anthers will have fallen off.

Also, notice that the scales are rounded above, not sharp-pointed like scales on some species, and that the scales' margins are transparently pale, like cellophane, but just inside the whitish margins the scales exhibit a broad band of dark purple, which is a little unusual for a spikerush scale.

Normally to be sure about a spikerush ID the tiny, achene-type fruit, or grain is examined. Our Uvalde plants were too immature for there to be grains, but a flower's ovary displays many of the features it will have when it matures into a grain, so some flowering spikes were snipped off, carried back to Juniper House, and studied below the dissecting scope. They're shown at http://www.backyardnature.net/n/14/140420eo.jpg.

In that picture the longish, banana-like items are anthers. The slender, whitish, string-like things are "perianth bristles" arising from the ovaries' bases. The roundish, greenish things on the left side of the picture are the grains. Notice that atop each grain there's a flattish, spade-shaped item. Those are "tubercles," and tubercle size relative to the grain, and their shape, vary tremendously from species to species, so they are important features. Just as important to notice is that the grains are flat on one side, but roundish on the other. Such grains are said to be three sided, and they bear 3-branched styles. The many spikerush species fall into one of two broad categories: those with two convex sides so that they are lens-shaped and have two style branches; or else with three sides like ours.

All these details lead us to our plant's identity. Sometimes called the Sand Spikerush, it's ELEOCHARIS MONTEVIDENSIS, native to warmer parts of the Americas, from Argentina north through Central America and Mexico, into the US, mainly in the southwestern states. It grows in many wet habitats, and apparently has a preference for sandy soils.



"Shortwave Static" from the September 29, 2008 Newsletter, at http://www.backyardnature.net/n/p/080929.htm

"Clouds in The Valley" from the December 24, 2007 Newsletter, at http://www.backyardnature.net/n/p/071224.htm


Best wishes to all Newsletter readers,


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