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

August 24, 2014

TERMITES WITH HIGHLY SPECIALIZED SOLDIERS
At the edge of a small roadcut through solid, naked limestone sparsely littered with dried-out juniper stems, liveoak leaves and dried-out grassblades, a dark line of what I assumed to be ants streamed from a dark cluster of the creatures into a hole in a crack in the rock two feet away. You can see a small section of the presumed ants at http://www.backyardnature.net/n/14/140824tm.jpg.

They were too small and fast-moving to see much about them, but from the beginning I wondered if they really were ants. In their line they kept much closer together than ants. Ants that close would tangle in one another's gangling legs. Also these roadcut creatures moved slower, more fluidly than ants. In fact, the streaming bodies reminded me of a narrow stream of dark liquid flowing across the limestone. Of course, once the above picture was on the laptop's screen I could see that with those thick bodies these weren't ants at all. They looked like termites, but I'd never seen such small termites, and I've not seen termites in such a rocky environment practically devoid of wood. Adding to the mystery, in the above picture notice the presence of at least two individuals much smaller than the others.

Though it was mid-morning, heavy overcast blotted out the sun, so I had to use a slow shutter speed on the camera. That explains why in my picture of them plunging into their hole some of their bodies are blurred because they were moving so fast, as you can see at http://www.backyardnature.net/n/14/140824tn.jpg.

When I'd first arrived, all the termites had been streaming from one spot among a cluster of liveoak leaves toward their hole, apparently already abandoning whatever had attracted them to that place. When I poked at their cluster hoping to see what they were doing, it only hastened their flight, and I never did figure out what they were doing in that spot.

Once nearly all the workers had gone underground, two individuals still out on the rock were photographed, and the surprising thing is that these little ones bore heads with long, sharp snouts, shown at http://www.backyardnature.net/n/14/140824to.jpg.

A photo of the last individuals on the surface entering their holes gives us a better look at the smaller ones, shown at the hole's sides at http://www.backyardnature.net/n/14/140824tp.jpg.

Using BugGuide.Net's taxonomy "browse" function, identifying these termites was easier than I could have hoped (Volunteer identifier Bea in Ontario being on vacation). Our pictures show TENUIROSTRITERMES CINEREUS, a species apparently found only in arid northeastern Mexico (Veracruz, Tamaulipas) and south-central Texas. Very little information is available about their life history and behavior, so I'm particularly happy to make this posting.

Though little has been written about Tenuirostritermes cinereus, another species of the same genus, Tenuirostritermes tenuirostris, occurs in Arizona, and it's been studied. One can assume many similarities of behavior between the two species. A 1974 paper on Tenuirostritermes tenuirostris by WL Nutting et al, mainly about the behavior of the smaller, pointy-headed ones -- which turn out to be the soldiers -- is freely downloadable in PDF format at http://psyche.entclub.org/pdf/81/81-167.pdf.

From that document I learn that our roadcut termite belongs to a subfamily of Termites, the Nasutitermitinae, regarded as containing the most highly specialized of termites. In more primitive termite species, the soldiers are equipped with fairly standard pincer-mandibles. The advanced specialization of the Nasutitermitinae's soldiers consists of the more primitive pincers having evolved through time into "non-functional stubs" -- the sharp points at the head's front end -- while at the same time the pointed snout became a sort of gun that could shoot for a fair distance droplets of liquid capable of incapacitating enemies, especially ants. This shooting apparatus is referred to as the "fontanellar gun." The paper says that "This fontanellar gun represents the apex of sophistication among the varied chemical defense mechanisms of the termites."

The above paper on the New Mexico species describes amazing coordination between the workers and soldiers. For example, before columns of workers begin their foraging, they gather in roundish clusters around their nest holes, with soldiers posted all around the cluster's periphery with their snouts pointed outwards. When workers return to their holes, soldiers are the last to enter the hole. This probably explains why the last individuals I photographed were soldiers. Also, it gives context to the second picture where soldiers were positioned at the hole's edge with their "guns" pointed outward as workers poured into the hole.

This was a wonderful find, and I'm tickled to document the species here. For future researchers needing exact location information, the nest lay about 500 meters north of the Uvalde/Real County line, in Real County, Texas, along the gravel road running up the valley of the Dry Frio River.

*****

REAKIRT'S BLUE CATERPILLAR
In the next section we look at a Golden Prairie-clover found this week, and one of our pictures there shows a flowering head hosting an unusual looking caterpillar. It's green and juicy like many caterpillars, but along its top surface run two low-toothed, purplish ridges, and that's something a little unusual You can see the caterpillar on the left of the flowering head at http://www.backyardnature.net/n/14/140824db.jpg.

Volunteer identifier Bea in Ontario was on vacation so I had little hope of identifying the caterpillar on my own. However, the less commonly encountered caterpillars often are very restricted with regard to the plant hosts they feed upon, and I knew that the host was the Golden Prairie-clover, so I looked for images of our caterpillar by searching on the keywords " Dalea caterpillar," "Dalea" being the Golden Prairie-clover's generic name. Within seconds pictures appeared showing what seems to be our prairie-clover caterpillar.

It's the caterpillar of the Reakirt's Blue butterfly, which happens to be our most common butterfly of that group known as blues. Our picture of the adult Reakirt's Blue seen from above is at http://www.backyardnature.net/n/a/uvalde/023.jpg.

The more commonly seen side view is seen at http://www.backyardnature.net/n/a/uvalde/036.jpg.

This caterpillar's appearance seems to change considerably as it grows. Though it's listed as foraging on many species in the Bean Family, many pictures on the Internet show individuals on Golden Prairie-clover, so maybe that's the preferred species.

*****

GOLDEN PRAIRIE-CLOVER
During these hottest, driest dog-days of a very droughty summer most of our wildflowers look pretty scrappy, their meager leaves curled and stiff with dryness, and if they're flowering at all, the blossoms generally are small and inconspicuous. That's certainly the case with one knee-high plant that was so austere and dusty looking I could hardly make out its stiff stems topped with modest, egg-shaped flowering heads amidst a general clutter of parched roadside grasses, as seen at http://www.backyardnature.net/n/14/140824da.jpg.

Up close, however, the grape-size flowering heads revealed themselves as hubs of activity, with attractions worth paying attention to, as you can see at http://www.backyardnature.net/n/14/140824db.jpg.

On the flowering head's left side notice the green caterpillar of the Reakirt's Blue butterfly, Echinargus isola, a common species here that feeds on many members of the Bean Family. Another indication that our plant belongs to the Bean Family is that the flower head's general appearance is very similar to that of a head of clover, and clovers are Bean Family members. Also, the yellow blossom is strongly bilaterally symmetrical, with a definite upper petal, two side petals, and two petals below fused along their common side into a scoop-like shape, exactly as with the Bean Family's "papilionaceous" blossoms. A view of the blossom in the head seen from the front is at http://www.backyardnature.net/n/14/140824dc.jpg.

More robust plants develop taller flowering heads, as shown at http://www.backyardnature.net/n/14/140824de.jpg.

The fuzzy heads disintegrate into individual hairy calyxes inside which there's a roundish, wafer-like legume normally with a single seed, or bean, as shown at http://www.backyardnature.net/n/14/140824df.jpg.

It's a bit unusual for legumes to remain inside their calyxes when they fall. I suppose the advantage in this case is that wind catches in the calyx's fuzz, helping the legumes travel into new territory.

The plant's pinnately compound leaves with their five leaflets also are typical of the Bean Family, as seen at http://www.backyardnature.net/n/14/140824dd.jpg.

Pictures on the Internet show more robust plants with more numerous flowers in their heads so probably our plants are somewhat stunted by the drought.

Though the yellow flowers display normal Bean-Family papilionaceous structure, they're still a bit peculiar looking because of how their two lower, fused petals -- the "keel" in papilionaceous terms -- are so slender and so stiffly project well beyond the other petals. Also, it's noteworthy how the two side, or "wing," petals, jut outward with their sides held horizontally.

This May we encountered all these traits in a different wildflower, except that the May one was very much smaller than the current knee-high one. The May wildflower was the Dwarf Prairie-clover, Dalea rubescens, with whom you can compare our present find at http://www.backyardnature.net/n/h/dalea.htm.

So, our knee-high plant must be another species of Dalea -- and notice that the name is not Dahlia, which is a garden favorite and member of the Composite or Daisy Family. Members of the genus Dalea are often known as prairie clovers or indigo bushes -- though the Indigo plant is not closely related. About 67 Dalea species are listed for North America, with several possibly turning up here. However, most species produce blue/violet/purple flowers, so that helps with identifying our knee-high, yellow-flowered species.

Here we have DALEA AUREA, known variously as the Golden Prairie-clover, Golden Dalea, and Silktop Dalea. It commonly occurs throughout the US prairie states from South Dakota, through here into much of northern Mexico.

Livestock find Golden Prairie-clover to their liking, which may explain why I haven't seen it except on a roadside through a ranch without livestock.

Native Americans used Golden Prairie-clover to treat diarrhea and colic.

*****

POINTED SANDMAT
During the hottest, driest days of summer, in the middle of a severe, multi-year drought, and issuing from little more than a narrow crack in limestone at the edge of a low roadcut, an ankle-high shrublet not only looked like it was thriving, but it was even flowering. You can see the tough little being at the edge of its roadcut, in a habitat so severe that its only macroscopic neighbor is the scale-like, brown Dermatocarpon lichen in the background, at http://www.backyardnature.net/n/14/140824eu.jpg.

A closer view shows the plant's stems sprouting from a single woody-looking trunk. Remembering that the plant is only ankle high, the greenish-yellow flowers and immature green fruits seem oversized, reminiscent of a bonzai, as seen at http://www.backyardnature.net/n/14/140824ev.jpg.

A close-up of its unusual and diagnostic flower structure is shown at http://www.backyardnature.net/n/14/140824ew.jpg.

Most folks who pay close attention to wildflowers will instantly recognize what's shown in the center of that picture as a classic example of the flowering strategy of the group of plants known as spurges -- members of the Spurge Family, the Euphorbiaceae. The thing to see in that picture is that, a little left-of-center, there's a rosy-green, cup-shaped structure with toothed, yellowish structures along its rim where petals might be expected in a flower. The cup-like thing is called a cyathium. Inside the cyathium there are several much reduced male flowers consisting of nothing more than a single stamen on a short stem, or pedicel. Amidst these male flowers, a single female flower's pedicel expands and curves over the cyathium's rim until it entirely repositions the green, whitish-hairy ovary -- the future fruit -- to outside the cyathium. In the picture you see the fruit hanging on its curved pedicel at the right of the cyathium.

So, this is a spurge , which means it's the genus Euphorbia, or -- if you believe in the existence of the genus Chamaesyce -- Chamaesyce. With recent genetic sequencing, most specialists now say that species earlier assigned to Chamaesyce actually are Euphorbias, so we'll call it a Euphorbia.

But, which Euphorbia? This one with its woody-like stem and exceptionally long hairs is unlike any I've ever seen. However, finding such an idiosyncratic plant is not a big surprise, since Euphorbia is the fourth largest genus of all flowering plants. The genus manifests itself in an incredible array of physical forms, and quite a number of species can be expected in our area. We've already profiled four from here in the Dry Frio Valley.

Unfortunately, the Flora of North America doesn't have its Euphorbia section ready yet. However, lately I've been in contact with noted Texas Botanist Bill Carr, and since he includes the word "spurge" in his email address, I figured he might not mind taking a look at the pictures. They were shipped to him, and he quickly replied: "Why that's Euphorbia acuta (Chamaesyce acuta, if you prefer), one of the most beautiful plants of the western hemisphere. It turns up from time to time on dry sunny limestone outcrops in that part of the world, but it's always a treat to see."

Isn't it wonderful to know people who recognize beautiful things when they see the?

EUPHORBIA ACUTA is sometimes known as the Pointed Sandmat, and in some literature its binomial is given as Euphorbia georgei. It grows only in southwestern Texas, southern New Mexico, and adjacent Mexico. Not much is known about it, but I suspect it's restricted to limestone, and is wonderfully drought resistant. Our plant seems to have been grazed on by animals, but it recovered nicely, actually growing into "one of the most beautiful plants of the western hemisphere."

*****

GREEN MILKWEED
In dry, marly dirt deposited by runoff from decaying limestone, a knee-high milkweed looked fairly healthy, despite the severity of our drought. It's shown at http://www.backyardnature.net/n/14/140824as.jpg.

The plant was easily identifiable as a milkweed not only because many milkweed species have opposite leaves (two per stem node) like these, which exude milky juice when injured, but also because the flower structure was very distinctly milkweed, as seen at http://www.backyardnature.net/n/14/140824at.jpg.

One way in which milkweed flowers are so unusual is that their flowers are adapted for a particular kind of pollination in which waxy pollen gathers and hardens into V-shaped structures called pollinia, which snag onto pollinators' legs. The pollinators then carry the pollinia to other flowers. Milkweed flower anatomy is so unique among all flowering plants that I provide a special page explaining them at http://www.backyardnature.net/fl_milkw.htm.

Usually we think of milkweed flowers as white or variously red to pink to purplish, so these greenish flowers are a little unusual. However, several milkweed species can produce greenish flowers and sometimes are known as Green Milkweed, so to know which Green Milkweed we have, we have to "do the botany."

Among the features helping us figure out which Green Milkweed this is are these:

# The plant's leaves are somewhat broad, not at all threadlike, and mostly opposite (two per stem node). Also they tend to bend upward, and are somewhat hairy, especially below.

These and other features point us to the Green Milkweed bearing the binomial ASCLEPIAS VIRIDIFLORA. Besides Green Milkweed it's also known as Green Comet Milkweed, Green Antelopehorn Milkweed, Green-flowered Milkweed, and by other names. The species fairly commonly is encountered throughout the eastern and central US, and contiguous Mexico.

Milkweeds are called milkweeds because when injured they issue milky-white latex containing a rich mixture of chemical compounds, some of which may be toxic or medicinal, depending on their dosage. Indigenous Americans chewed our Green Milkweed's roots to make a poultice that could be applied to rashes, a nursing baby's sore gums, rheumatic joints, and sore eyes. The root was chewed to relieve the sore throat, and infusions of the root have been used to treat diarrhea in children. As often is the case with plants producing milky exudates -- in accordance with the baseless Doctrine of Signatures, which states that plants signify to us their uses with features of their appearance -- infusions of the plant have been used to increase the milk flow of nursing mothers.

While I'd hesitate to use raw milkweed products medicinally, because of the inability to control dosages of the many potentially toxic compounds, the plants' unopened flower buds, immature leaves, and newly emerged sprouts can be cooked and eaten, but the water in which they are cooked should be discarded.

But, it'd be a shame to eat this or any other milkweed species. They are important nectar sources to many pollinators, Monarch Butterfly larvae eat their leaves, and they're simply too pretty to eat. Milkweeds have suffered greatly because of rampant, thoughtless mowing and herbicide use.

*****

A SKULLCAP'S HYDROBALLOCHORY
On the dry slope of a shallow roadcut through limestone a certain small wildflower caught my attention not with its flowers but with its dried-out calyxes, which glowed warmly tan-colored in the morning light. You can see its admittedly somewhat thirsty and scrappy looking clump of stems at http://www.backyardnature.net/n/14/140824sc.jpg.

Up close, the desiccated calyxes displayed a form as unusual and distinctive for this particular group of plants, as cyathia are for the euphorbias. You can see what I mean at http://www.backyardnature.net/n/14/140824sd.jpg.

When you have a plant with opposite leaves like these (two leaves per stem node), and calyxes with such pronounced "hoods," you need to think of the Mint Family's genus Scutellaria. Scutellaria species often are referred to as skullcaps, the name reflecting the presence of the hoods atop the calyxes. Hoods in some species are just low ridges or other shapes, but I don't recall having ever seen a Scutellaria hood so definitely shaped like the head of a Lacrosse stick.

I recognized this plant as the handsomely purple-flowered Wright's Skullcap, Scutellaria wrightii, we found on the Dry Frio's dried-out river bed last September. You can see the pretty flowers at that time with their still-green calyxes at http://www.backyardnature.net/n/h/skullcap.htm.

Something was going on with these extraordinary calyxes, so I did some Googling to see if anything has been published about the calyxes of the Wright's skullcap. And, it had!

In the November 1, 2010 issue of The Texas Journal of Science, Allan Nelson and Jim Goetze published a paper on how the calyxes of two skullcap species, one of which is our Wright's Skullcap, facilitate the dispersal of the plant's nutlet-type fruits during rain, in a process known as "hydroballochory." Their paper is freely downloadable at http://www.highbeam.com/doc/1G1-303757972.html.

In that paper they write, "When a drop of rain hits the cup-shaped top of a yellow or brown scutellum, it dehisces and falls off the plant and the resulting mechanical energy from this event causes the scales to throw the nutlets away from the plant." The hood is what he's calling a scutellum. "Dehisces" means "splits open." Most of the calyxes on our plant already had lost their tops, leaving only the lower halves, with the nutlets already thrown away from the plant. You can see a couple of empty lower halves at http://www.backyardnature.net/n/14/140824se.jpg.

So, a raindrop hits the cup, causing both the calyx's hood-bearing top to be knocked off, and the lower part of the calyx, which holds the nutlet-type fruits, to bend down beneath the raindrop's weight. When the lower part of the calyx rebounds after being knocked downward, it tosses the nutlets lying on its scoop-like lip away from the plant, dispersing them away from the parent plant.

How about that? Anytime something strikes you as a little unusual, it's worth Googling the matter to see if something special is going on.

*****

FEATURED ESSAYS FROM THE PAST:

"Sycamore Totem" from the June 13, 2004 Newsletter, at http://www.backyardnature.net/n/p/040613.htm

"It's Really Beautiful, Isn't it? Isn't it... ?" from the August 24, 2007 Newsletter, at http://www.backyardnature.net/n/p/070824.htm

.

*****

Best wishes to all Newsletter readers,

Jim

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