March 16, 2014
Last month we looked at dragonfly naiads, which are special aquatic nymphal forms. Pictures are at http://www.backyardnature.net/n/a/df-nymph.htm.
We couldn't identify those naiads because I hadn't known to notice the mouthparts, which is necessary. This week another dragonfly naiad turned up in a submerged green mat of filamentous algae and cyanobacteria cloaking a rock. This naiad was identical in structure to the previous ones, but black, as shown at http://www.backyardnature.net/n/14/140316na.jpg.
This time I coaxed the little critter onto his back so that the machinery of his mouthparts became visible, which you can see at http://www.backyardnature.net/n/14/140316nc.jpg.
The shoe-shaped structure beneath the head and neck are the mouthparts, known as the labium. At the labium's rounded front you can barely see a kind of rim. The rim is composed of two merging pincers or jaws now closed against the labium. When the naiad grabs prey, the whole labium shoots forward like an arm with a hinged elbow, the pincers open and sink into the prey, the arm retracts to below the head to where the mouth is located, and then the naiad chews its prey.
Seeing what the mouthparts look like and using the well illustrated "Dragonfly Larvae Identification Key" it can be determined that our naiad belongs to the Darner Family, the Aeshnidae.
Michael Overton's "Odonates of Uvalde County, Texas Field Checklist" for our county lists five Darner Family species, so all I can say is that our naiad is some kind of darner dragonfly, of which the most widely spread and best known is the Common Green Darner.
OLEANDER GONE WILD ON THE DRY FRIO
On the cobblestone floodplain of the Dry Frio River over a mile from any residence, a bushy tree turned up that was familiar, yet its glossy greenness seemed very out of place in that, winter-locked, isolated little valley. You can see it at http://www.backyardnature.net/n/14/140316ol.jpg.
It's familiar because it's one of the most frequently planted ornamentals in the world's tropics and subtropics, so we've seen it often in Mexico, and it's out of place because surely no one planted it here on this isolated stretch of the Dry Frio. It's the Oleander, NERIUM OLEANDER, which as been so widely cultivated for such a long time that its native region is uncertain, though southwestern Asia has been suggested, as has the Mediterranean.
The above plant is adorned with brown, cigar-sized fruits currently splitting open to release fuzzy seeds. Pods are shown at http://www.backyardnature.net/n/14/140316om.jpg.
Technically, these fruits are known as follicles, a follicle being a dry fruit that splits open only along its front suture, and which is the product of a simple pistil. Notice that the follicles are vaguely like milkweed pods, which similarly split open to release seeds whose long hairs carry them on the wind. The similarity is accountable by the fact that, now that the Milkweed Family has been merged with the Dogbane Family, both milkweeds on Oleanders are members of the Dogbane Family, the Apocynaceae. However, hairs of milkweed seeds elegantly radiate from atop a slender stem atop the seed, umbrella-like, while hairs on Oleander seeds are more generalized, as you can see in a seed close-up at http://www.backyardnature.net/n/14/140316on.jpg.
While we're looking, the Oleander's leaves just by themselves are pretty enough, as shown at http://www.backyardnature.net/n/14/140316oo.jpg.
Even close up the leaf veins' primary symmetry and ultimate reticulations are good to see, as seen at http://www.backyardnature.net/n/14/140316op.jpg.
If this were a normal bush, leaves on its lower branches would have been eaten off by deer, who grossly overpopulate this area. Deer avoid Oleander leaves because they are toxic. Texas A&M's "Plants of Texas Rangelands" Oleander page says that as few as ten to twenty medium-sized Oleander leaves can kill an adult horse. They are toxic to all animal species, the page asserts, and many livestock and pets are poisoned, usually because they eat Oleander clippings or dead leaves. Even dead leaves remain toxic, though they become palatable. Compost containing Oleander leaves has been incriminated in poisoning.
For my part, I appreciate any pretty bush that can survive the drought, pollution and physical abuse that Oleander can. With regard to its toxicity, you can kill yourself by eating too much salt, but we live it, as should be the same with Oleanders. With global warming about to reconfigure the biosphere in many unforeseen ways, eventually people may be happy to have any plant around able to survive the daily weather.
Not far upstream from the escaped Oleander yet another escapee caught my eye. This one also was bushy but was much less robust, leafless, and consisted of only a few stiff, slender, brown stems tipped with brown, peppercorn-like fruits, shown at http://www.backyardnature.net/n/14/140316vx.jpg.
The plant's leaves, like its secondary stems, arose two per node, or "opposite," which for the identification process eliminated most possibilities, because one leaf per node, or "alternate," is a little more typical. The plant's general aspect and its opposite leaves directed me to that region of the Phylogenetic Tree of Life graced by the big branches of the Mint and Verbena Families. So, what plants have I found around here in those families, and who could have produced these fruits? A closer look at the hard, spherical fruits curiously surrounded at their bases by unusually large, close-fitting, bowl-like calyxes is at http://www.backyardnature.net/n/14/140316vy.jpg.
One possibility was the Whitebrush, of the Verbena Family, but it's hard to imagine that bush's small flowers with their slender, curved tubes producing such substantial fruits with bowl-shaped calyxes. The same was true of the Shrubby Blue Sage of the Mint Family. Another possibility was the Hemp-Tree, or Chaste-Tree, of the Verbena Family, and the more I thought of that possibility the more I liked it, for it seemed that I remembered that bush's calyxes cupping the blue flowers' bases as they do on these fruits. You can see this at the bottom of our Hemp-Tree page at http://www.backyardnature.net/n/w/vitex.htm.
Back at Juniper House an image search on Hemp-Tree fruits scored a perfect match. So, Hemp-Tree, or Chaste-Tree, VITEX AGNUS-CASTUS, a native of the Mediterranean region, but which has escaped into the landscape across the southern half of the US, and in many other countries as well.
During the search for pictures of Hemp-Tree fruits, several pages turned up selling herbal medicines concocted of fruits and leaves of the plant. The HerbFacts.co.UK website claims that the plant "has been used in herbal medicine for centuries to relieve symptoms associated with female hormonal imbalances such as menstrual cramps, mood swings and water retention."
On the Vitacost.com website, which sells 90 capsules for $3.99, users have posted comments. Two women say that the capsules did nothing to stop their hot flashes, but another says it did, and another writes, "My PMS is GONE," continuing to say that the capsules must be taken regularly in order to work.
Across North America, this is the very season for paying special attention to tree buds. That's because they're about as large and well formed as they'll become. Moreover, it's a real pleasure to see how buds on different tree species are so different from another, and how they display such diverse field marks. For instance look at the comparison of two buds from trees found here at http://www.backyardnature.net/n/14/140316x2.jpg.
That's a Sycamore bud at the left, and Ohio Buckeye buds at the right.
Already two profound differences between the buds are apparent, for Sycamore buds occur one per stem node (they're alternate), while buckeye stems bear two buds per node (they're opposite).
Notice that the yellowish Sycamore bud is protected by only two large, wrapping-around scales, while the brownish buckeye's bud is armored with several smaller scales.
Also, look how different the leaf scars -- leaf scars forming where last season's leaf petioles broke from the stems. The sycamore's leaf scar forms a narrow ring practically surrounding the bud, while the buckeye's is broad and shield-shaped, and situated entirely below the bud.
In each leaf scar you can also see tiny, roundish scars, where pipe-like "vascular bundles" broke when the leaf snapped from its stem at the end of the season. Vascular bundles consist both of xylem and phloem, the xylem transporting water and minerals up to the leaf, the phloem carrying photosynthesized carbohydrate from the leaf to the stem to be stored.
TARCRUST ON A LONG-DEAD SYCAMORE
A big Sycamore on the Dry Frio's floodplain died so long ago that now it's just a massive, head-high trunk standing like a detached elephant's leg along the road. One section on the disintegrating trunk was so obviously blackened by fire that at first I didn't bother looking closely at it, but after I'd passed it by, it occurred to me how curious it was that only a small part of the trunk should be burnt, with no indication of fire elsewhere, either on the trunk or neighboring trees. Going back, I looked closer at what's shown at http://www.backyardnature.net/n/14/140316fu.jpg.
Could such a hard, black, thin crust be a fungus? Breaking away a tiny piece of the crust to examine its edge with a hand lens, something interesting turned up, shown at http://www.backyardnature.net/n/14/140316fv.jpg.
Along the broken edge, tiny, oblong chambers are visible, their bottoms nearly reaching the wood the crust adheres to, and their tops nearly reaching the crust's exposed surface. These chambers reminded me of "perithecia" we've seen in certain fungi. Perithecia are hollow fruiting bodies whose interior walls bear microscopic spore-producing cells called asci. In fact, back in the Yucatan we saw the fungus called "Dead Man's Fingers" whose black, brittle surface-crust was chambered with perithecia similar to these, as you can see at http://www.backyardnature.net/yucatan/earth-tg.htm.
So, the hand lens revealed that we had a fungus, and I suspected the fungus was related to Dead Man's Fingers, though that fungus forms a fingerlike fruiting body unlike the thin, black crust covering our Sycamore's dead wood.
Back at Juniper House the dissecting scope provided a better view of the perithecia in a cross section of the crust, shown at http://www.backyardnature.net/n/14/140316fw.jpg.
The crust's exposed surface is at the picture's top. You can see that tops of some perithecia reach the crust's surface, where they form small mounds. You can think of the mounds as tiny volcanoes from which spores are released from tubes extending from the perithecia to the crust's surface. These bumps are hard to see on such a black substrate but by overexposing a dissecting scope view of the crust's surface, they more or less became visible, as seen at http://www.backyardnature.net/n/14/140316fx.jpg.
The surface's cracks or fissures are typical of the species.
Our Dead Man's Fingers is a "sac fungus," or member of the fungal phylum Ascomycota, and further it belongs to the order Xylariales, so that's where I began looking for our black crust fungus. It didn't take long to determine that we had a fairly common species occurring throughout much of the world -- though usually it's overlooked. Often it's called Common Tarcrust. It's DIATRYPE STIGMA, the "stigma" in its binomial referring to the "spots" or bumps on the crust's surface.
Though our Common Tarcrust grew on a Sycamore, references place it on oaks, beech, birch, maple and other species. It's saprobic, meaning that it derives its nourishment from nonliving or decaying organic matter, in our case the old Sycamore trunk. The Sycamore's dead wood was so dry and crumbly that it's hard to imagine it nourishing our fungus. However, the tarcrust's action on the wood probably help make it crumbly to begin with.
CHARA ALGA #2
Last August we looked at an alga in the Dry Frio River that normally is encased within a brittle mantle of calcium and magnesium carbonates, making the organism stiff and brittle. It was Chara, genus Chara. Numerous Chara species exist, and they're hard to identify to species level. Last August's Chara can be reviewed at http://www.backyardnature.net/n/x/chara.htm.
The other day a similar but much more slender and delicate looking alga turned up, also in a quite pool at the Dry Frio's edge, shown at http://www.backyardnature.net/n/14/140316ch.jpg.
You can get a feeling for how large the organism is compared to my hand at http://www.backyardnature.net/n/14/140316ci.jpg.
Back at Juniper House the dissecting scope revealed the pretty picture at http://www.backyardnature.net/n/14/140316cj.jpg.
Those are typical male and female reproductive structures for Chara species. The spherical, reddish item is an antheridium producing sperm, while the darker, oblong item above it is the oogonium containing an egg. The oogonium when mature will be a little larger than the antheridium. Note that at the oogonium's top there's a crown of several cells, which is typical of Chara oogonia.
This Chara species was neither very brittle nor much encrusted with calcium and magnesium carbonates, though in the above picture a few transparent mineral crystals can be made out on the alga's surface.
Chara species provide homes for many micro and macro invertebrates, which in turn are eaten by fish and other wildlife such as amphibians, reptiles, and ducks. When Chara dies, its decomposition by bacteria and fungi provides food called detritus for many aquatic invertebrates.
The other day it was cool and dry and we were expecting a warm front out of Mexico to come up from the southwest possibly bringing us some desperately needed rain. At mid day unusual clouds appeared in the southwest and I figured they might be the leading edge of that front. You can see them at http://www.backyardnature.net/n/14/140316ac.jpg.
Being halfway "white and fluffy" I pegged them as cumulus clouds, and since their tops were wispy almost like high-altitude cirrus clouds composed of ice crystals, they must have been relatively high cumulus, or "altocumulus." The Clouds-Online.Com website lists thirteen altocumulus species, subspecies and special forms, so which was this? Google's image-search feature using the keyword "altocumulus" quickly turned up named pictures of clouds like ours.
They're Altocumulus castelanus clouds, sometimes known as jellyfish clouds because of the small part dangling below each cloud, reminiscent of tentacles beneath jellyfish floating on the water's surface. I read that Altocumulus castelanus form when moist air becomes trapped between layers of dry air, so probably that day the leading edge of our expected Mexican front with its moisture probably was indeed wedging its way into our too-dry air.
The "tentacle" part of the cloud, known as the "trailing virga," consists of raindrops evaporating as they fall from the cloud, never to reach the ground. Several cloud types, especially in arid areas, produce virgas, so that's a good word to remember.
NAVIGATING BY SILHOUETTES
Each morning well before the eastern horizon pales with dawn I run on the road in the valley. With moonlight it's easy to see every crack and pothole, and even when there's no Moon, starlight shows the road's general location. I've memorized where the bigger potholes are.
When there's heavy cloud-cover, it's harder. Then I navigate by the known positions of trees and electrical poles, which produce diffuse silhouettes against even the darkest sky. It's beautiful to run at that time of the morning, even when it's so dark.
I've heard that sometimes blind people offered the chance to see hesitate to undergo the needed procedures because their lives without vision already are rich and meaningful. When blind, one becomes acutely sensitized to sounds, odors and touch, which reveal an utterly engaging and fulfilling world, so why destabilize that perceived reality with visual clutter?
Moreover, we're all navigating life somewhat blindly; our senses reveal only a small part of the world around us.
Imagine how things would look if we could see in the ultraviolet, X-ray or radio part of the electromagnetic spectrum, not just the narrow bandwidth we refer to as "visible light." Cows and wild deer tend to align their bodies north-south while relaxing, but not when under high voltage power lines, so what would the sense of ease feel like that encourages facing one way but not another? The world of atoms humans deal with constitutes only 4.6% of the Universe, the rest being dark matter and dark energy we can't touch, feel or measure, so what are we missing here?
What good do these kinds of thoughts do, and how does running in the dark help anything?
For one thing, it starts my day reminding me that everything during the rest of the day will be detected and understood through my own set of sensory filters, which have been wired and tuned by fairly random life processes. And they will be analyzed by an onboard computer, my mind, with its own peculiar wiring and biochemical issues. Therefore, this thing I think of as myself not only is ephemeral but, since we define ourselves in terms of how we fit into the perceived world around us, "I" am on shaky ground; "I" am being defined by erratic and incomplete sensory perceptions.
As such, these pre-dawn runs counsel that I needn't take myself too seriously.
Yet, at the jog's end when the Great Horned Owl who hangs out at Juniper House murmurs his greetings, and a bubble of fragrance from the flowering Agarita bush is passed through, the run's teaching of detachment is counterbalanced. My sense of belonging with this owl and with this bush summons a Middle Path for governing the rest of the day, as I continue navigating by silhouettes.
FEATURED ESSAYS FROM THE PAST:
"Enchanted City at Dawn" from the May 22, 2011 Newsletter, at http://www.backyardnature.net/n/p/110522.htm
"Warm Breezes" from the December 22, 2002 Newsletter, at http://www.backyardnature.net/n/p/021222.htm
Best wishes to all Newsletter readers,
All previous Newsletters are archived at http://www.backyardnature.net/n/.