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 11, 2013

RINGLEGGED EARWIG
The big Golden Zucchini plant that produced such extravagant and good-tasting squash in the spring now looks pretty desperate and probably it'll produce no more. Its stem is brown and spongy, apparently hollowed out by vine borers, and now occupied by a whole community of organisms nibbling on mushy, stinky stem remains. I split part of the stem lengthwise, hoping to find the vine borer larva but found none. However, I did meet an old acquaintance, shown inside the opened stem at http://www.backyardnature.net/n/13/130811ew.jpg.

Last year in Mississippi where on many summer days I ate my fill of pears, I got to know this insect well, for often inside a pear that looked perfect lying on the ground, when it'd be picked up, there'd be a hole in the pear occupied by one of these critters.

It's the Ringlegged Earwig, EUBORELLIA ANNULIPES. The forceps-like "pincers" at the rear end cue us to its being an earwig, and you know it's the Ringlegged species because of the dark bands ornamenting its legs. Across the southern US this is a very commonly encountered species, plus it's less common as far north as southern Canada. It's an invasive, probably from Europe, who has invaded many of the Earth's warmer countries. Some earwig species bear wings, but not this one, so it's amazing that the Ringlegged has spread so widely across the planet.

The first two thoughts one has upon meeting a Ringlegged Earwig in a pear, a squash stem or someplace else, are: What's with the "pincers," and; is it a "good" or "bad" insect?

The pincers can pinch, but they are two small and weak for a human to worry about. They're used in self defense, for catching prey, and sometimes during sex.

As far as being good or bad, the general consensus is that, being omnivores and often preying on caterpillars, beetle larvae, and leafhoppers, they probably benefit the garden as much as they bother it. One unfortunate thing they do is to leave poop on lettuce leaves.

*****

A CLIFF-EDGE FORESTIERA
On a certain limestone ledge overlooking the Dry Frio Valley the view is so pretty that even the kind of people who leave trash go there to sit, and kids take the time to deface the smooth stone with carved Bible verses. For a long time I've been waiting for a tree beside the overlook to flower so I could figure out who it is. In mid July its flower buds seemed about ready to burst, so last weekend I hiked up to the overlook hoping for flowers. However, the flowering period already had passed, so all I found were the flowers' brown, withered remains. You can see if you can identify a twig from the tree at http://www.backyardnature.net/n/13/130811fo.jpg.

The simple, 1½-inch-long (4cm) leaves arise two per stem node -- they're "opposite" -- so that's an important field mark, since most woody species produce one leaf per node, so they're "alternate." The stiff, straight twig also bears large, white "lenticels," which are warty, window-like structures enabling air to enter the stems. A close-up of some withered flowers is at http://www.backyardnature.net/n/13/130811fp.jpg.

I could have kicked myself for missing the fresh flowers, but these dried-up ones still reveal a lot. First, several flowers are shown, not just one with many dried-up stamens. Can you see that in places three or more stamens arise from a common stem, or pedicle? That pedicle and whatever issues from its top comprises a flower, and the ones in our picture bear no female parts, so they're unisexual male flowers. Also, there appears to be no corolla.

A relatively small number of temperate-zone plant families produce woody plants with opposite leaves, and of that group only a fraction develop unisexual flowers. Toying with that insight, eventually I blundered into the family to which our mystery tree belongs: It's the Olive Family, the Oleaceae, best known to North Americans as the home of Lilacs, ash trees, and ornamental Fringetrees. Also, in the swamps of Mississippi, we had the water-loving Swamp-Privet, Forestiera acuminata.

Our cliff-edge tree also is a Forestiera, though obviously it occupies a habitat opposite to that of our swamp species. It's FORESTIERA RETICULATA, in books known as the Netleaf Forestiera.

Netleaf Forestiera is endemic to about a dozen counties of the Edwards Plateau in southwestern Texas, and a bit of arid northern Mexico. Little information is available about it. On the Texas A&M page for the species I read that "It is not a common shrub in Texas, and there is little botanical information available. Like all forestieras, it has male and female flowers on separate plants. They appear in early spring, usually before the leaves, and female plants produce dark blue-black berries that are an important wildlife food source."

That description's assertion that the tree flowers in early spring before leaves develop doesn't coincide at all with our observation. Such early flowering is typical for other Forestieras, including the hairy-stemmed Forestiera pubescens also occurring in our area, so maybe someone just guessed that our species would do the same.

Whatever the case, this is a wonderful find, a rare, poorly known tree and pretty species, just the kind of discovery one always hopes to make.

*****

WILD INDIGO
In much of North America these are the dog days of summer; here on most days the temperature hits 100 or above (38C). Sunlight burns and dazzles; in the afternoons you just want to sit in the shade where there's a good breeze. If during these mad-dog hours you wander the cobblestone floodplain beside the little Dry Frio River, you might come upon stands of waist-high bushes with such wispy branches and slight, pale leaves that the whole plants heave and sway. You squint through sweat trying to focus and hardly see what's before you. A picture of one of those chimerical presences is shown at http://www.backyardnature.net/n/13/130811in.jpg.

Up close, details emerge: Alternate, pinnately compound leaves mantled with short, silvery hairiness; slender racemes of flowers arising on stiff peduncles where leaf petioles adjoin the stem... You can see this at http://www.backyardnature.net/n/13/130811io.jpg.

In such heat and intense sunlight apparently the plant's flowers remain fresh only briefly, for in any given raceme only one or two blossoms among several can be found open at one time. In the raceme above the open blossoms there are flower buds not yet open, and below the open blossoms the corollas and stamens already have been cast off, leaving only pistils rapidly developing into fruits. A close-up showing two open flowers is at http://www.backyardnature.net/n/13/130811ip.jpg.

A large petal rising above (the banner) with two side petals (the wings) and two lower petals joined along their common margin to form a scoop-shaped structure (the keel)... Seeing this, instantly we know that we're dealing with the huge Bean Family. Such flowers are said to be "papilionaceous," and most Bean Family species produce flowers with such banners, wings and keels. And if we have a member of the Bean Family, then the bush must produce legume-type fruits. These are shown at http://www.backyardnature.net/n/13/130811iq.jpg.

At first I thought we had one of several species of locoweeds, genus Astragalus, famous for intoxicating cattle so that they stagger around behaving as if they were loco. However, when I "did the botany," the plant turned out to be even more interesting: It's a "wild indigo," INDIGOFERA LINDHEIMERIANA, listed in books as Lindheimer's Indigo. It's a "real indigo," too, since it belongs to the genus Indigofera. The indigo bushes from which the commercial blue dye called indigo once was extracted are mainly Indigofera suffruticosa and Indigofera tinctoria.

Several species of "wild indigo" occur across North America, but our Lindheimer's Indigo is endemic to just a few counties of the limestone-based Edwards Plateau of southwestern Texas and parts of two arid, adjacent Mexican states. The Wildflowers.org website describes Lindheimer's Indigo as "A shrubby plant found on alluvial soils and limestone gravels along streams in the Texas Hill Country," which is exactly where we found it.

The plant is poorly documented and I find nothing about its medicinal use or source as a dye. It's been seen, however, that the caterpillars of Reakerts Blue, Grey Hairstreak and Dogface Butterflies feed on Lindheimer's Indigo herbage.

*****

TEXAS MILKWEED
Beside a trail through the hillside forest of Ashe Junipers and Texas Liveoaks near the Center, there appeared a wildflower spectacular enough for its presence to penetrate my heat-dazed consciousness. It's shown at http://www.backyardnature.net/n/13/130811as.jpg.

With such thick leaves arranged two per node on a stem topped with such a white snowball, even without looking at the individual flowers, this was clearly some kind of milkweed. On hands and knees looking closer, each little blossom making up a snowball displayed the very distinctive and lovely milkweed-flower structure shown at http://www.backyardnature.net/n/13/130811au.jpg.

Milkweed flower anatomy is so complex and unusual that we have a webpage showing what's what; you may want to identify the parts of our hillside plant's flowers using the webpage's labeled pictures at http://www.backyardnature.net/fl_milkw.htm.

A side view of our hillside flowers appears at http://www.backyardnature.net/n/13/130811at.jpg.

These flowers are very similar to those shown on our milkweed page, except that our hillside ones are all white, and the stem or "corona limb" holding the corona hoods and horns above the petals is much taller and slenderer.

This is the Texas Milkweed, ASCLEPIAS TEXANA, endemic to just a few counties in the Edwards Plateau area of southwestern Texas, far western Texas, and a couple of states in adjacent northeastern Mexico. It's described as living in sandy or sandy loam soils, or even gravel, at woodland edges, openings, ditches, ravines, depressions, along streams and river banks, which is a bit moister than where our plant occurred.

Texas Milkweed is so rare and poorly known that I find no information on its historical uses. However, all milkweeds are known to be good sources of nectar for pollinators, and caterpillars of some of our favorite butterflies, such as the Monarchs, eat the herbage.

Most milkweed leaves are unusually thick and juicy, which would seem to make them desirable to leaf-eating animals. However, milkweeds use three main defenses to limit damage caused by herbivores: hairs on the leaves; chemical toxins, and; milky latex that oozes from wounds, clogging up a herbivore's mouthparts. I've always assumed that latex and toxins in milkweed leaves were fairly sophisticated innovations, and that as such during the milkweeds' evolutionary history, those defenses mush have evolved relatively recently. However, DNA studies indicate that more recently evolved milkweed species depend less on hairs, toxins and latex than "more primitive" ancestral species. Recently arisen species are more likely to simply grow so fast that caterpillars can't keep up with the growth!

*****

LYRELEAF PARTHENIUM
In the Yucatan one of the most common weeds sprouting up in sidewalk cracks and in dry, compacted soil along highways was one often called Feverfew in English. It was the Composite/Sunflower-Family member Parthenuium hysterophorus. That invasive, tropical and subtropical species is also common here. Our page on the species is at http://www.backyardnature.net/yucatan/feverfew.htm.

Here in southwestern Texas there's a very similar native "feverfew," the one shown growing in a natural prairie patch at http://www.backyardnature.net/n/13/130811pa.jpg.

The flowering heads are the two species are almost identical. You can see our prairie species' heads at http://www.backyardnature.net/n/13/130811pb.jpg.

However, the two species are easy to distinguish because their leaves look different. The lobes of our prairie species' leaves are broader and less divided than on leaves of the weedy species, as shown at http://www.backyardnature.net/n/13/130811pc.jpg.

Our prairie species is PARTHENIUM CONFERTUM, in books often referred to as the Lyreleaf Parthenium, though any parthenium species might be called a feverfew.

Our Lyreleaf Parthenium mostly occurs in arid northern Mexico, but extends into the US in southwestern Texas and southern New Mexico and Arizona. It's not weedy like its look-alike relative. The Flora of North America describes its habitat as "Sandy plains, openings in mesquite grasslands." In our area they're in grassy spots whether mesquites are nearby or not.

By the way, the most famous Parthenium is Parthenium argentatum, commonly known as Guayule. Historically Guayule was collected for its white latex, which could be boiled down to make rubber; efforts were made to grow it for rubber during World War II. Nowadays Guayule is being planted again because rubber made from its latex is more stretchable than synthetic rubber, and is less likely to cause allergic reactions than other forms of natural rubber.

*****

SPREADING LAZY-DAISY
On our limestone hill where Ash Junipers and Texas Liveoaks thin so that house-size grassy areas break out, sometimes the grass is punctuated with a sprinkling of half-inch-wide (12mm), white flowers as shown at http://www.backyardnature.net/n/13/130811ld.jpg.

Such small, disperse flowers put one in the mind of bluets or similar wildflowers, maybe of the Pink Family, the Caryophyllaceae, but if you get on your hands and knees and look closely at a blossom, you don't see what you expect. A shot from below a blossom is at http://www.backyardnature.net/n/13/130811lf.jpg.

There, instead of seeing a green calyx with five sepals subtending a white corolla, you find sharp-pointed, overlapping scales of differing sizes. This is as you'd find in the big Composite or Sunflower Family, but flowering heads in that family seldom are so small and positioned in such and open, diffuse inflorescense. However, when you flip over the blossom and look at it from above you see what's at http://www.backyardnature.net/n/13/130811lg.jpg.

That's the "eye" of a blossom as seen beneath a dissecting scope. The yellow eye is surrounded by the bases of five white "ray flowers," and the eye itself comprises seven or eight "disc flowers," one of which is open. The open disc flower clearly displays five sharp-pointed corolla lobes, and five yellow anthers fused along their edges to form a cylinder, exactly as is normal for flowers in flowering heads of the Composite Family. This really is a composite flower, after all.

Before plunging into "doing the botany" on these tiny flowers I made special note that the wildflower's individual flowering heads appeared at the tips of exceedingly long, slender stems, or peduncles, in a much-branched, very open, panicle-type inflorescence. The panicle was several times higher than the plant's modest leafy stem, and the stem and leaves themselves were heavily invested with stiff, slender hairs, as shown at http://www.backyardnature.net/n/13/130811le.jpg.

Having never met this kind of composite before and with the flower parts being so tiny, this was a hard ID to make! Still, in the end the plant revealed itself as CHAETOPAPPA EFFUSA, in books referred to as the Spreading Lazy-Daisy or Spreading Leastdaisy. It's a poorly documented and little-known species, mainly because in the whole world it's endemic to just a dozen or so counties here in southwestern Texas, in the Edwards Plateau region. The online Flora of North America describes its habitat as "Limestone cliffs, ledges, bluffs, steep hillsides, sometimes in seepy areas, oak-juniper, oak, or mixed deciduous woods; 300–500 m," which is exactly where we find it.

The genus Chaetopappa comprises eleven species occurring only in arid northern Mexico and the south-central and southwestern US. In Uvalde County we have three species, so in our area Chaetopappa is a genus worth knowing.

*****

PRAIRIE TEA
In the much-disturbed, tramped-on, thin, gravelly soil atop limestone bedrock within just a few feet of Juniper House here at the Center, the most common wildflower definitely is the leg-calf-high one shown at http://www.backyardnature.net/n/13/130811cr.jpg.

Note that this herb's 5/8ths-inch-long (15mm) leaves array themselves like leaves on a tree, the tree branching and rebranching from slender trunks, like a miniature shadetree. Up closer you see more peculiarities, such as the green, immature, egg-shaped fruits shown at http://www.backyardnature.net/n/13/130811cs.jpg.

With this kind of plant it's important to notice features of the ovary, so a closer look at an immature fruit tipped with four style arms is shown at http://www.backyardnature.net/n/13/130811cv.jpg.

An immature fruit such as the picture shows is by definition a flower's maturing ovary. In the picture, though the flower's ovary and style arms -- female parts -- are obvious, no male stamens are to be seen. That's because we're seeing a female flower. Flowers in this species are unisexual and typically occur together in the same flower cluster. A male flower displaying four white petals and six or seven stamens is shown at http://www.backyardnature.net/n/13/130811cu.jpg.

In that close-up you also see that the hairs seem to be doing something unusual. You can see a leaf's hairs as they appear beneath the dissecting slope at http://www.backyardnature.net/n/13/130811ct.jpg.

The hairs are "stellate," or starlike, with numerous slender, sharp-pointed spines radiating from a central point. Several plant families produce stellate hairs, but I've ever seen stellate hairs with more spines or growing closer together than these.

This is such a distinctive, unusual kind of plant that you recognize the group to which it belongs just by looking at it -- not by slogging through lots of obscure details. It's a member of the genus Croton, of the big Euphorbia or Spurge Family, the Euphorbiaceae. However, there are lots of crotons, with about ten species possibly occurring in our region, and at least three species already listed for Uvalde County. Therefore, even if at first glance you recognize that this is a croton, you end up "doing the botany" to figure out the species.

Our Juniper House species is CROTON MONANTHOGYNUS, distinguished from the other species by these fieldmarks: It's an herb instead of a woody bush; it's ovaries are topped with only two styles divided to their bases so that it looks like there are four styles (most other species have more style branches), and; the male flowers bear only six or so stamens (less than most other species). This is one of the most commonly occurring crotons in North America, found throughout most of the south-central and southeastern states, though curiously absent from most eastern coastal states.

Croton monanthogynus is commonly called Prairie Tea or sometimes One-seed Croton. On the Internet at least one page claims that tea can be brewed from the leaves, and that the leaves can serve as a general spice, even "as a basil substitute in your pesto." It's true that when you brush against the plant an intense, spicy, refreshing fragrance clouds all around you, but I find the leaves' taste too strong to use for anything. Also I worry about their toxicity, since many plants in the Euphorbia Family are dangerous, such as the beans from Castor plants. I've noticed that in overgrazed pastures cattle avoid eating Prairie Tea, even when it's the main species left standing.

In fact, I first noticed Prairie Tea when I was installing insulation beneath Juniper House. Upon crawling from under the building I'd find my naked, sweaty skin burning wherever I'd touched Prairie Tea, and my neighbor Phred reported the same sensation, though cool, dry skin doesn't seem to suffer. Whatever the case, I'm not brewing tea from Prairie Tea.

I'm glad to have the plant around Juniper House, however, especially because fruits of croton species are famed for their large, oily seeds that are much eaten by birds. In some places crotons have been called Dove Weeds because doves favor the seeds so.

*****

RAIN-LILY PODS FILLED WITH BLACK SEEDS
In grassy prairie patches at the edge of limestone cliffs overlooking the Dry Frio River nowadays you run across green, herbaceous, leafless, foot-tall stems rising from the ground, topped with items like those shown at http://www.backyardnature.net/n/13/130811ze.jpg.

These are fruiting pods of rain lilies. The one at the right is so immature that not only has it not split apart but also still is in the process of bursting through and casting off the remains of the former flower's corolla-like perianth. The capsule at the left has matured and opened so widely that black seeds lie in the capsule's three chambers, or "locules." The seeds have lost all connections to the plant body so a nice breeze or the merest touch of the stem sends them flying. A rabbit running into such an open pod would scatter seeds for several feet, which is exactly what the plant wants.

We've documented two very similar rain lily species here, Zephyranthes drummondii and Zephyranthes chlorosolen. I'm unsure which species this is, though I know that in this area Zephyranthes drummondii was flowering in the spring, so I'm guessing that that's what we have. The other species' capsules and seeds wouldn't look much different.

*****

FEATURED ESSAYS FROM THE PAST:

"Hummingbirdness," from the January 21, 2008 Newsletter, at http://www.backyardnature.net/n/p/080121.htm

"Apple Tree Haiku" from the June 21, 2009 Newsletter, at http://www.backyardnature.net/n/p/090621.htm

*****

Best wishes to all Newsletter readers,

Jim

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