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

September 28, 2014

WHISTLING DUCKS DOING NOTHING
Across Whistling Duck Lagoon at Cook's Slough Nature Park on Uvalde's south side, several Black-bellied Whistling Ducks stood on a submerged log not far from the water's edge, looking as if they stood atop the water, as seen at http://www.backyardnature.net/n/14/140928wd.jpg.

I wasn't nearly as close to the ducks as that picture suggests, nor do I have a powerful telephoto lens. I stabilized the camera on a bench in a shelter across the lagoon from the ducks, took a shot at very high resolution, and later greatly enlarged a tiny part of the picture, using PhotoShop. I hadn't even known what species they were until I saw the picture on my laptop.

I watched these ducks for about half an hour thinking they might do something interesting, but all they did is what you see, just stand there with one eye pointed at me.

But, that was kind of interesting in itself. For, Black-bellied Whistling Ducks are known to spend a good deal of time "doing nothing." They're reported as spending whole days in flooded rice fields and golf courses near rivers apparently just looking around, or at one another. I used to think that tropical America's big iguanas spent their days "doing nothing," but later I learned that what they're really doing is helping bacteria in their guts break down the large amounts of vegetative material they eat, by keeping their bodies warm as they bask in the sun. Black-bellied Whistling Ducks mostly eat plant material, too, though also aquatic invertebrates and arthropods when the can, so maybe our ducks were standing there doing their best to encourage good digestion.

Our Black-bellied Whistling Duck page with more pictures and information about the species is at http://www.backyardnature.net/n/b/whistlin.htm.

*****

GHOST CHRYSALIS
Suspended among branches on a Nandina bush next to the house I was painting, a pure white butterfly chrysalis turned up with narrow black bands. It's shown at http://www.backyardnature.net/n/14/140928ch.jpg.

Chrysalises constitute the resting pupal stage between a butterfly's caterpillar and adult forms. Though I've never seen a chrysalis colored like this white one, its shape and the manner by which it suspends itself from a twig with a thin silk connecting its upper middle section with the twig is exactly like that of our most commonly noticed chrysalis, that of the Pipevine Swallowtail. You can see that butterfly, its caterpillar and its more normal colored chrysalis at http://www.backyardnature.net/n/a/pipeswal.htm.

Assuming that this is indeed a Pipevine Swallowtail chrysalis -- and volunteer identifier Bea in Ontario assures us that it is -- why was this one white? If you look at our picture closely you can see black holes at its bottom. This looks like where an internal parasite might have exited the chrysalis's body after killing the metamorphosing pupa by feeding on it.

The parasitic wasp known as Trogus pennator inserts its eggs into swallowtail caterpillars, the eggs hatch into larvae that then feed on the living caterpillar. However, the larvae don't injure the caterpillars enough to kill them, for the caterpillars still manage to pupate. But the pupae do die, leaving behind pupa shells like ours from which adult Trogus pennator wasps eventually emerge. You can see a Trogus pennator laying its egg on a Black Swallowtail caterpillar at http://bugguide.net/node/view/431190.

So, maybe it's just normal for parasitized Pipevine Swallowtail chrysalises to turn white when they die. That doesn't explain the white chrysalis's elegant black bands, though.

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PUNCTUREVINE
Beneath glaring, skin-sizzling, midday sunlight, on bare, hard-baked dirt washed down from a pond levee at Cook's Slough Nature Park on Uvalde's south side, a ground-hugging little herb was as green and laden with little yellow flowers as if it were a lush, cool spring day. Seeing how other plants couldn't even get a foothold in such a hostile environment, leaving the entire area naked but for this species, you just had to admire the little plant's ability to flourish. You can see a supper-plate-size one at http://www.backyardnature.net/n/14/140928tr.jpg.

A portrait of a flower and its attendant pinnately compound leaves is at http://www.backyardnature.net/n/14/140928ts.jpg.

Notice at the bases of the two petioles the erect, narrowly triangular, green stipules. Seeing these in conjunction with the pinnately compound leaves, automatically you think of the big Bean Family. However, the flower is nothing like a bean flower; it's more like a buttercup's blossom. Also, members of the Bean Family only rarely have two leaves per stem node. So, seeing this peculiar combination of flower and leaves, already we know we have something here of a kind we don't ordinarily deal with. A closer look at the flower, showing even more unusual details is at http://www.backyardnature.net/n/14/140928tt.jpg.

Surrounded by the ten stamens, of course the greenish, egg-shaped item is the ovary, or future fruit. That means that the thing looking like a green starfish powdered with pollen grains and clamped atop the ovary must be the stigma. But, have you ever seen such a stigma with arms growing down an ovary's sides like this?

Despite these abnormalities, the moment I saw this plant I knew it, because of painful memories associated with it from back in my days of backpacking in the Mediterranean area. I remember walking along a beach in Spain and deciding to dump the backpack and plop onto the sand to gaze at the sea. I sat down on some of these plants, and that's how I learned the hard way that they produce fruits of the kind shown at http://www.backyardnature.net/n/14/140928tu.jpg.

You can imagine that those things hurt when you sit on them, or walk barefooted through them.

I also remember them from the summer of 2005 when I was exploring California's Sierra Nevadas. My bee-keeping friend Buck brought me the plant asking for an identification because his bees found the plant's yellow blossoms a fantastic nectar source, and he was thinking about getting seeds and planting whole fields of them, even if they did produce such aggravating fruits.

So, the plant is an invasive species from tropical regions of the Old World -- southern Europe, southern Asia, throughout Africa, and Australia -- where it thrives in deserts and poor soil. In the Americas it's spread to everyplace where there's hot, uncharitable soil. Being so widespread, it goes by many English names including Bullhead, Cat's Head, Devil's Eyelashes, Devil's Thorn, Devil's Weed, Goathead, Caltrop, Tackweed, and the one that seems to be popular in the US, Puncturevine, despite it's not being viney at all.

It's TRIBULUS TERRESTRIS, a member of the Caltrop Family, the ZYGOPHYLLACEAE. Maybe the best known native American member of that family is the Creosote Bush, which covers vast portions of the US southwestern desert region. Puncturevine now occurs throughout most of the western US, and is scattered here and there east of the Mississippi.

Beyond producing such an unfriendly fruit, which can even puncture a bicycle tire, Puncturevine's foliage is toxic to livestock, especially sheep, when consumed in quantity. It's not surprising, then, that on both the federal and state level it's listed as a noxious weed, and the Texas Parks & Wildlife Department prohibits its introduction. However, the TexasInvasives.Org website says that "Puncturevine is currently controlled by the stem weevil (Microlarinus lypriformis) and seed weevil (M. lareynii), introduced from Italy as biocontrol agents in 1961."

On the Internet if you do a search on Puncturevine's binomial, Tribulus terrestris, the vast majority of returned links will be to pages that neither refer to the plant's hurtful fruits nor their noxious herbage. They'll claim that extracts of the plant increase the body's natural testosterone levels and thereby improve male sexual performance and help build muscle, and they'll probably try to sell you some tablets. In fact, one study has shown that Puncturevine extracts can indeed alter sexual behavior in castrated rats, apparently by stimulating androgen receptors in the brain.

Before society became so fixated on male sexuality and muscles, the plant was used in traditional medicine as a diuretic (makes you pee), demulcent (forms a soothing film over mucous membranes, relieving minor pains and inflammations), tonic (tones you up), aphrodisiac and laxative.

*****

NOSEBURN
In each of the last four or so Newsletters we've looked at spindly, not-very-spectacular members of the Spurge Family, the Euphorbiaceae, mostly growing in thin, very dry soil atop limestone. This week we have another one, a whole new genus, and it also turned up in thin soil atop limestone, at the edge of a roadcut. This spate of such plants is mostly explained by the fact that this time last year I was distracted by more commonly occurring and more attention-getting plants. I just overlooked these homely little beings. You can see the one found this week, with its narrow leaves conspicuously low-toothed along their margins, at http://www.backyardnature.net/n/14/140928tg.jpg.

At the above picture's far left you can see the Spurge Family's telltale field marks: A three-lobed, greenish fruit separated from some stamen-bearing male flowers barely visible clustering at the branch's very tip. The Spurge Family produces such unisexual flowers, sometimes with both sexes on the same plant, but sometimes on separate plants, and this one has them on the same plant. A close-up of a cluster of male flowers at a rachis tip, with a female flower just below them, with its yellow-orange, widely spreading, three-branched stigma, is at http://www.backyardnature.net/n/14/140928ti.jpg.

A shot of a more developed ovary, or immature fruit, is at http://www.backyardnature.net/n/14/140928th.jpg.

Among key features distinguishing the genus of our Spurge Family member are these:

These field marks lead us to the genus Tragia, members of which often are known as noseburns, apparently because if somehow the stinging hairs get into your nose, they're bound to burn. Eleven noseburn species are listed for Texas, of which six might be found in our area. Ours is the most commonly occurring one, sometimes called the Branched Noseburn, TRAGIA RAMOSA. It's native to the southwestern and south-central US and northern Mexico, where it grows in scrub, woodland, and other desert and plateau habitats.

Our plants aren't as heavily invested with longer, stinging hairs as those in pictures on the Internet, but hairiness often varies between populations, and our plants' consistently very narrow leaves and other traits make it convincingly Tragia ramosa.

The Navaho called our plant c'os be'yi'c'ol, which translates to "vein-spurter," a name applied to several unrelated plants with slender stems and leaves used for stopping bleeding. In southern Nuevo León, a state in northeastern Mexico, Branched Noseburn and Leatherstem (Jatropha dioica) have been boiled together to make a wash for treating hair loss.

*****

FLOATING PRIMROSE-WILLOW
In a treatment pond in Cook's Sough Nature Park on Uvalde's south side, all summer I've been watching a certain population of aquatic plants grow and grow, waiting for their pretty yellow flowers. However, now in early fall when I'm preparing to leave Texas, still there are no flowers, so I'm profiling this plant despite its flowerless state, just because it's something worth seeing. It's at http://www.backyardnature.net/n/14/140928lu.jpg.

I'm not the only one to notice the plant's advance across the pond, for along the banks someone has dragged in several bushels of it and dumped it into a heap... where the leafy stems seem to be thriving as well as in the water. But, still, there no flowers are being produced.

I've been expecting yellow flowers because back in Mississippi we had this plant, which produced the blossoming stems shown at http://www.backyardnature.net/n/08/080707lw.jpg.

A view into the interior of that flower is seen at http://www.backyardnature.net/n/08/080707lx.jpg.

Back then we called the plant Floating Primrose-willow, though other common names for it include Creeping Water-primrose and Water-primrose. It's LUDWIGIA PEPLOIDES. Species of the genus Ludwigia often are referred to as seedboxes because of the boxy shape of their many-seeded fruits. Ludwigia is a member of the Evening Primrose Family, the Onagraceae, in which flowers often bear four large, yellow petals (though Floating Primrose-willows anomalously have five). Evening Primrose flowers are among that minority of blossoms with inferior ovaries -- with sepals, petals and stamens arising above the ovary, not at its base.

One field mark for Floating Primrose-willow is that as their leaeves emerge above the water from submerged stems, often they form little rosettes, as shown at http://www.backyardnature.net/n/14/140928lv.jpg.

Another good field mark is that the leaves' herring-bone-patterned veins are so pale, and the midveins expand conspicuously toward their bases, reminiscent of chard leaves.

Floating Primrose-willow is native to tropical America and warmer contiguous zones, in the US occurring coast to coast in the southern two-thirds of the country. It's also spread as an invasive weed in much of the rest of the world's warmer parts, where its aggressive growth often gets it classified as a troublesome aquatic noxious weed. It can choke ponds and canals, and in large numbers can even lower oxygen content in water, which is bad new for fish.

However, Creeping Water-primrose has a certain talent that someday may cause it to be regarded as a highly honored guest in such treatment ponds as those around which Cook's Slough Nature Park is organized. That talent is that the plant absorbs toxic substances from the water, such as herbicides, pesticides, and pollutants. Once the plants have absorbed the toxins, then they need to be removed from the water and deposited where the toxins will do no harm.

*****

SIGNALGRASS
Up against the green-painted, corrugated tin walls of an observation building at Cook's Slough Nature Park on Uvalde's south side some healthy-looking grasses were flowering and I couldn't quite place them. They're shown at http://www.backyardnature.net/n/14/140928ur.jpg.

What knee-high grass with , long, wide leaves like these issues pyramid-shaped flowering heads, or inflorescences, with such straight side-branches? The general inflorescence shape reminds me of the barnyard grasses, genus Paspalum, but up close the spikelets don't look at all like Paspalum, as seen at http://www.backyardnature.net/n/14/140928us.jpg.

With a single grain-producing floret per spikelet, the spikelets look like those of the panic-grasses, genus Panicum. However, the manner by which the spikelets arose on only one side of the flattish inflorescence branch, or rachilla, (they're "secund") is something I don't recall seeing among the panic-grasses. Those long hairs also are good field marks worth remembering.

Deciding that either the plant was closely related to the panic-grasses or else actually a very unusual panic-grass itself, I checked the ligule -- the little wall-like thing that may or may appear where a grass blade meets the stem, and which can take many forms. This grass's ligule is shown at http://www.backyardnature.net/n/14/140928ut.jpg.

The white-hairy ligule stretching across the inside curve of this grass blade could well be that of a panic-grass, but other grass genera can have such ligules, too, so this doesn't prove much. It was just those "secund" spikelets that worried me about calling this a panic-grass.

In the end our grass turned out to be something other than a panic-grass, though very closely related. It's Browntop Signalgrass, UROCHLOA FUSCA, a mostly tropical American grass occurring from Argentina and Paraguay north through the Americas into the southern US from Arizona to Oklahoma and Florida. The "browntop" part of the common name refers to the fact that sometimes spikelets more mature than ours are deep purple-tinged. Even in our picture you can see a little purplishness developing at the spikelets' very tips. Also, in more mature spikelets, typically cross-veins connect the conspicuous green veins running from bottom to top. If you look closely you can see such cross-veins beginning to form in some places.

Browntop Signalgrass's habitat preference is described as moist, often disturbed areas at low elevations, frequently occurring as a weed, and occasionally grown for forage and grain. That fits our grass well, for I didn't see it out in the dry scrub. Moreover, I halfway suspect that someone sowed it around the observation shelter when it was built.

Worldwide, about a hundred species of the genus Urochloa are recognized, and they're all tropical or otherwise preferring warmer climes. Browntop Signalgrass is so closely related to the genus Panicum that in the past it was assigned to that genus. It's also resided in the genus Brachiaria. Really, taxonomists have had a hard time figuring out just where our plant belongs on the Phylogenetic Tree of Life.

One theory about the name signalgrass relates to those "secund" spikelets all on one side of their rachilla. They're like signal flags all pointing one way, signaling the direction the wind is blowing...

*****

BLEEDING OAK CRUST FUNGUS
Right beside a house I was painting, where two large roots converged at the base of a trunk of a thriving Texas Live Oak, Quercus fusiformis, there was a fungus the size of a dinner plate I'd never seen before. It's shown at http://www.backyardnature.net/n/14/140928fu.jpg.

This is not a typical mushroom with a stem, or even a shelf-type fungus sticking from the trunk like a horizontal ear, but rather it's formed as a crust, with the fungus's bottom attached to it's substrate. Most of it is attached to the trunk but notice just to the right of the trunk, at the picture's very top, there's a whitish colony on organic-matter-rich soil. In fact, smaller populations occurred all around the trunk, sometimes on wood, sometimes on the ground, sometimes looking as it little groupings had been splattered there messily. Up close the large body shows more peculiarities at http://www.backyardnature.net/n/14/140928fv.jpg.

It's a crust with a mostly gray surface but white along the edges where new growth extends its size, and white in the center area where cauliflower-like growths arise. And on some of the white central cauliflowers there are amber-colored drops of liquid, shown closer up at http://www.backyardnature.net/n/14/140928fw.jpg.

Assuming that these might be dewdrops or drops of sap from the tree, I almost didn't photograph them, but then I remembered that here we seldom get dew and drops of sap weren't visible elsewhere, so I took the picture, and I'm glad, since now I know that they constitute an important field mark. In the centers of the bases of many of the droplets in that picture you can see pinprick-like holes. I'm guessing that they're wormholes from which juices inside the fungus have exuded.

One last picture showing the white fungus border extending up a limestone rock on the ground is at http://www.backyardnature.net/n/14/140928fx.jpg.

Having never encountered a crust fungus like this I hardly knew where to begin the identification process. I settled on the not-so-technical approach of doing a Google image-search on the keywords "fungus crust oak." Almost instantly a thumbnail popped up showing something similar to our find under the heading "Bleeding Oak Crust Fungus."

Before long I'd learned that in Europe the Bleeding Oak Crust Fungus is fairly commonly documented, and considered to be a member of the genus Stereum. However, in North America, Bleeding Oak Crust Fungi are poorly documented. The Stereum species most closely resembling our live-oak tree seems to be Stereum gausapatum. One fact supporting that observation is that the genus Stereum is said to consist of two groups of species, the "bleeders" and the "non-bleeders," and Stereum gausapatum is a bleeder, like ours with its amber-colored juices issuing from little holes.

Thinking this might be Stereum gausapatum, at MushroomExpert.Com I read Michael Kuo writing that " ... Stereum hirsutum, Stereum complicatum, and Stereum gausapatum, at a minimum, might best be seen as positions along a continuum, and would-be Stereum identifiers should probably be prepared for collections that don't quite settle themselves neatly into one or another position."

Add to this the fact that many experts now accept that the nice genus Stereum needs to be divided into several hard-to-remember genera, and you have a confusing situation. One of those genera is Chondrostereum, which can produce forms looking like ours. So, this is one of a few very rare instances when it seems to me more reasonable to use the rather vague English name "Bleeding Oak Crust Fungus" than a technical binomial about which even the experts are unusually circumspect.

My guess is that eventually the world will decide that it's useless to try to assign classic binomials to certain groups of organisms, such as this one. Also, this group of fungi seems to be so little studied in the Americas there's a very good chance that our Texas Live Oak's population simply doesn't have a generally accepted scientific name we can apply to it.

Stereum species normally take their nutrients from decaying organic matter -- they're saprobic -- so maybe where our fungi climb onto the living tree they're actually drawing nutrients from decaying bark, or a gob of rotting leaves the wind blew into the crack, and so are not parasitic.

*****

DESTROYING ANGELS RETURN
This time last year some famously poisonous Destroying Angel mushrooms, Amanita bisporigera, turned up in rich soil on a shady slope at the base of our hill here, and this year they've returned at the very same time and in the same place. However, this year they're fewer and shorter, probably because this year has been drier than the last. Last year's impressive population can be seen at http://www.backyardnature.net/n/x/amanita3.htm.

You can compare those with this year's crop at http://www.backyardnature.net/n/14/140928am.jpg.

Even with these short mushrooms, if you dig away the leaf litter you can see the Amanita field marks consisting of a conspicuous, collar-like ring or annulus halfway up the stem, and the stem arising from a white cup, or volva, as shon at http://www.backyardnature.net/n/14/140928an.jpg.

To be even more certain that you have an Amanita you need to confirm that the mushroom's spores are white. Normally that means plucking a mushroom's cap, or a portion of it, placing it top-up on a surface, and noting the color of the dusty pollen that over time accumulates beneath the cap. A typical Amanita spire print I made several years ago is shown at http://www.backyardnature.net/f/sporprnt.jpg.

To make a spore print your mushroom's cap must not be so young that it's not dropping spores yet, or so old that the spores already have been released, plus it might take several hours to get a nice print. Of course, you'd like to see your mushoom's spore color in the field, but that's rarely possible. However, with this week's short-stemmed Amanitas it could be done in some cases where the caps nearly lay flush with the forest floor, as was the case shown at http://www.backyardnature.net/n/14/140928ao.jpg.

Do you see the whitish powdering of the black organic matter below that cap's gills? The whiteness is produced by spores released from the above gills. If the spores had been dark, we'd been out of luck -- and our mushrooms wouldn't have been Amanitas.

Only rarely can you determine spore color so quickly and easily, but it's nice when those opportunities arise.

*****

FEATURED ESSAYS FROM THE PAST:

"Clogged Ear" from the April 7, 2002 Newsletter, at http://www.backyardnature.net/n/p/020407.htm

"Calluses" from the April 6, 2003 Newsletter, at http://www.backyardnature.net/n/p/030406.htm

*****

Best wishes to all Newsletter readers,

Jim

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