December 13, 2015

A SPINED-MICRATHENA SPIDER GOLDEN MORPH
In eastern North America, if you're walking along a forest trail and run into a spider web strung across the path, there's a good chance that the web will have been constructed by the very common and distinctive Spined Micrathena spider. Spined Micrathenas are easy to recognize because their abdomen bear five conspicuous, broad-based spines, and all the ones I've seen are boldly patterned with black and white stripes and mottling. The tops of their abdomens are mostly white, with black spines.

This week a spider of the same size, shape and with the same patterning of the Spined Micrathena turned up weaving her web between the tips of a tufted agave plant, but this individual was orange/gold and yellow, not black and white. You can see her at https://www.backyardnature.net/n/15/151213sp.jpg.

As she hangs upside-down spinning out her web, the silken threads are produced atop the lobe on the abdomen's bottom -- directed skyward -- as seen at https://www.backyardnature.net/n/15/151213sq.jpg.

Spiders aren't the favorite subjects for volunteer identifier Bea in Ontario, and she couldn't be sure of her name, but she wrote back that our golden spider on the agave looked most like the Spined Micrathena, despite it not being black and white. When I checked out the matter, most Internet photos of the species do show black-and-white individuals, but a few are golden like ours, and the species' technical description says that certain morphst can be yellow-orange, so it looks like that's what we have.

The Spined Micrathena, MICRATHENA GRACILIS, is described at the Encyclopedia of Life (EOL) website as occupying dense deciduous forest in eastern North America, south through Mexico into Central America. Here our forest is only semi-deciduous, plus our spider spun on an agave along a weedy roadside, so in our area they show some habitat flexibility.

Up north often I've wondered why Spined Micrathenas were so boldly patterned, making them more visible. I guessed that it was to help low-flying birds and wandering mammals crossing the forest openings the webs tended to occupy to see the spider, and not crash through their webs. However, a paper by Natasha Vanderhoff and others addressed the very question of why Spined Micrathenas are so attention-getting. When they compared prey-capture rates of less brightly colored individuals with those of brighter ones, they found that the "... spiders’ color and pattern may attract prey items to their webs, thus increasing their foraging success."

I read that when the sun goes down Spined Micrathenas eat their webs, then build them again at dawn. Also, males, about half the size of females, don't build webs, but rather weave a "mating thread" onto the web of the female of their choice. When everything is in place, he quickly runs out and mates. Websites often report that the mating can be deadly for the male, but the EOL website says that "Sexual cannibalism appears to be rare in this species and has been observed only when two males courted a female simultaneously."

Spined Micrathenas are completely harmless to humans.

*****

BUSHMINT
The little one-lane gravel road to a garbage dump near the hotel zone was hemmed in with head-high weeds and bushes that were as dense and shadowy-green as the late rainy season in the tropics can make it. Jutting from the wall was the peculiar-looking plant shown at https://www.backyardnature.net/n/15/151213hy.jpg.

It was the fruiting and flowering, panicle-type head of some kind of robust-, disheveled- and aggressive-looking herb. Up close, its flowers were surprisingly small and delicate looking, as shown at https://www.backyardnature.net/n/15/151213hz.jpg.

In that picture notice that the calyxes' long hairs are interspersed with shorter, gland-tipped hairs. The gland-tipped hairs give the herbage a sticky feeling and must contain fragrant oils that contribute to the herbage's powerful odor. Northerners knowing their local wildflowers and garden herbs will recognize the smell and appearance of the flowers as typical of the Mint Family, the Lamiaceae. A view into the corolla confirming Mint Family features is shown at https://www.backyardnature.net/n/15/151213hx.jpg.

Mint Family features seen here include the bilaterally symmetrical corolla -- cut it down the middle from top to bottom and each side presents a mirror image of the other -- and the two stamens. Most kinds of mints bear four stamens but a small group, including this one, bears only two. Note the dark purple nectar-guides orienting pollinators toward the flower's bottom, where nectar is produced. The plant's leaves almost seem too large and leathery to belong to a mint, but that's the way these are, as shown at https://www.backyardnature.net/n/15/151213hw.jpg.

Our big herb is HYPTIS SUAVEOLENS, thought to be native to the tropical Americas from Mexico and the Caribbean south into South America, plus it's invasive in most other tropical countries worldwide. Being so attention-getting and widespread, it bears many English names, including Bushmint and Pignut. In Mexico it's often known as Chan.

Bushmint's odor is not one of those sweet-spicy fragrances the Mint Family is famous for, but rather it's minty with strong undertones of a musky-oily kind. When you smell it, for the first half second you really like it, but then the odor grows heavy and musky, and eventually almost nauseating. Such potently smelling herbs often turn out to have medicinal value, and that's the case with Bushmint.

The online Atlas de las Plantas de la Medicina Tradicional Mexicana says that in the Sixteenth Century Bushmint's seeds, ground raw and eaten, were used against diarrhea. Those who coughed and spit blood took the ground root. Even still, in Mexico country people treat diarrhea with it, in some parts taking a tea of the roots while fasting, while in the Yucatán a tea is brewed from the leaves.

Lab tests confirm that the plant's essential oils are antibiotic, so there may be something to Bushmint's uses against bacteria-caused diseases.

A 2014 research paper out of India dealing with Bushmint, by Hitendra Padalia and others, describes it as "... rapidly invading tropical ecosystems across the world, including India, and is major threat to native biodiversity, ecosystems and livelihoods."

I've only seen this one plant around here, though.

*****

RED MORNING GLORY
Among the colorful riot of morning glory vines gracing our landscape these days there's a species that, though its flowers are smaller than those of most morning glories -- only about an inch long (2.5cm) -- are brilliantly red, and very eye-catching. This sometimes weedy, fairly common roadside vine climbs to the top of shrubbery and sets its crimson blossoms even higher atop long peduncles that overtop the herbage, as seen at https://www.backyardnature.net/n/15/151213ii.jpg.

A close-up showing the flowers' white anthers extending well beyond the corolla tube -- different from most morning glory species -- and how the corollas' narrow tubes abruptly expand at their mouths is shown at https://www.backyardnature.net/n/15/151213ij.jpg.

There we also see the vine's heart-shaped leaves, whose smooth margins sometimes develop low, pointy lobes, so that they almost look like ivy leaves.

The flowers are so unlike most morning glory blossoms that it's a good idea, just to firm up the identity, to take a closer look at the flower structure, which is done at https://www.backyardnature.net/n/15/151213ik.jpg.

In that picture, in the cluster of slender items at the left, the right-most item in the cluster is whiter and slenderer than the five other things, and the roundish thing atop it is more spherical. That's because the five items at the left are stamens topped with pollen-producing anthers, while on the the right we have the flower's style, with the spherical structure being its stigma. The stigma's spherical, or "globose," shape is important to notice because in the Morning Glory Family, the Convolvulaceae, certain genera closely related to "real morning glories," but which themselves are not members of the morning glory genus Ipomoea, possess oblong or otherwise slender stigmas -- notably the bindweeds. But our vine's globose stigma puts it in good standing among "real morning glories," genus Ipomoea.

Our red-flowered morning glory is IPOMOEA HEDERIFOLIA, not to be confused with the abundant and weedy Ipomoea hederacea, the Ivy-leaved Morning Glory, with similar, ivy-like leaves but very different flowers. Our red-flowered vine is native to tropical and subtropical North, Central and South America, and is even found in the US Southeast and farther north along the coast. Since it occurs in the US and draws such attention to itself, it's graced with many English names, including Red Morning Glory, Cardinal Vine, Scarlet Morning Glory, Starglory, Redstar, Mexican Morning Glory, Scarlet Creeper, Trompillo, and many others.

In Mississippi we had a commonly occurring and often-planted morning glory with very similar blossoms, the Cypress Vine. However, Cypress Vine's leaves were finely dissected, reminiscent of green fish skeletons, or combs with teeth on both sides. That was Ipomoea quamoclit. Sometimes the two species hybridize, suggesting that they share a recent ancestor. It's striking that two species with such similar flowers can produce such drastically different leaves.

Interestingly, though Red Morning Glory's flowers are clearly adapted for pollinators such as long-beaked hummingbirds and hawk-moths with long proboscises, they're capable of self-pollination.

*****

"MAYA" TANGERINES
Quotation marks surround "Maya" because officially there's no such thing as a Maya Tangerine. I'm calling what we have here that, though, because our local tangerines -- ones planted in people's yards -- are different from others I've seen, in that their fruits are smaller, greenish and relatively seedy. I'm figuring that our trees -- at least the one near my hut -- are descendants of ancestors brought here long ago, before modern tangerine cultivars were developed.

First of all, take a look at a tangerine we plucked from a tree in Querétaro, north-central Mexico, back in 2007, at https://www.backyardnature.net/q/tangerin.jpg.

I think that that fruit is more or less what is sold in markets up north, though maybe the northern ones have thicker skins so that they ship better. Now look at the smaller, greener, thinner-skinned fruit we have here, one whose juicy parts are coated with much less white, pulpy material (the mesocarp), whose skin comes loose much less easily, and which is much less sweet -- in fact fairly sour -- compared to the the Querétaro one and those in northern supermarkets, at https://www.backyardnature.net/n/15/151213td.jpg.

Our local tangerine fruits become orange only when lying on the ground bug-eaten, bird-pecked and rotting. You can see a green one that would be ready for picking if it hadn't been spoiled by the resident Golden Fronted Woodpecker at https://www.backyardnature.net/n/15/151213ta.jpg.

When a citrus tree bears tangerines it's obviously a tangerine tree, but most of the year when no fruits are in sight, it can be hard to distinguish a tangerine tree from other non-fruit-bearing citrus trees, such as orange, lemon, lime and grapefruit trees. Hard, that is, unless you pay close attention to the leaves' size and the condition of their petioles. You can see our tangerine tree's leaves at https://www.backyardnature.net/n/15/151213tb.jpg.

Tangerine leaves are smaller than other common citrus types. They're about 1½ inch long (4cm) as opposed to lime leaves that are about 2½ inches(6.5cm), and orange leaves, which over twice their length, and grapefruit leaves, which can be up to five times as long. Also, notice that the leaves' stalks, or petioles, are jointed at their attachment with their blades. A closer look at an "articulated petiole" is at https://www.backyardnature.net/n/15/151213tc.jpg.

Citron petioles aren't jointed like that, but the other commonly known citrus leaves are. Also, notice that the petioles are "winged" with thin ridges along their sides. In some citrus species the wings are much expanded, as on the Sour Orange we looked at here in 2011, shown at https://www.backyardnature.net/n/11/111127nk.jpg.

Among the citrus species, tangerine leaves are noted for their smallness, and their narrowly winged petioles.

In everyday English, a tangerine fruit is simply a small, orange-like fruit whose skin comes off easily and whose interior parts separate without much trouble. However, in taxonomy, the lines between tangerine plants and their cousins aren't at all clear. You might enjoy looking at a page entitled "What’s the Difference between Tangerines, Clementines, and Mandarins?"

Nowadays some specialists maintain that the Tangerine plant constitutes an independent species called Citrus tangerina. However, others think it's a hybrid between two stand-alone species, and still others, maybe the majority, regard it as a variety of the Mandarin Orange, in which case its name would be CITRUS RETICULATA.

Whatever its taxonomic affiliation, this season I've enjoyed my share of fruits from the tangerine tree near my hut, often adding their acidy little sections to my morning oatmeal. And I'm glad to show our "Maya Tangerines" to the world, because they may be a long forgotten ancestor of today's mass-produced market tangerines. As such, our Maya Tangerines' genes, evolved in the context of the tropics' many diseases, someday may be much sought after, when plague ravages the vast monocultures of cultivars producing super-sweet, super-orange-colored, super-easy-to-break-apart fruits so popular in markets nowadays.

*****

OUR HOLEY LIMESTONE
Roadcuts along the highway between Pisté and the entrance to the hotel zone show interesting geological features, such as are shown at https://www.backyardnature.net/yucatan/roadcut.htm.

During the last month the exposure shown in that picture has been obliterated as they widened the road. However, new roadcuts have been exposed, and as rain washes them clean they show ever more interesting details. You can see some at a new cut at https://www.backyardnature.net/n/15/151213rc.jpg.

The Yucatan Peninsula is a big slab of limestone, and limestone is famous for its caves and underground rivers. The above picture shows two openings to subterranean chambers, the one on the left mostly blocked by boulders dumped there by the road crew, apparently in a half-hearted attempt to seal it, and the one on the right also is mostly blocked, but not so completely. These give an idea of how common such "solution features" are in this area's limestone.

The picture was taken quite close to Chichén Itzá ruins. Recently I heard through the Maya-laborer grapevine that some local laborers were part of a team that discovered that the big pyramid at Chichén Itzá sits atop a cave, which may have played part in the ancient Maya priest's job of communicating with spirits of the underworld. And one can imagine the effect of a priest emerging from atop the pyramid when the whole community is sure that no one has climbed those sacred steps for a long time.

I've not heard of such a discovery being formally announced, so it may be only a rumor. However, it's fun to think about when I bike past these openings on my way to Pisté to buy bananas.

*****

ADDICTED TO DISTRACTION
Eric in Mérida directed us to Tony Schwartznov's recent article in the New York Times entitled "Addicted to Distraction." You can freely access it here.

Schwartznov quotes a study finding that the average white-collar worker spends about six hours a day on email, and that's not counting time spent online shopping, searching and keeping up with social media. He sees such obsessive behavior as a kind of addiction, and explains it in terms of the brain’s craving for novelty, constant stimulation and immediate gratification, all combined with the “compulsion loop.” An example of a compulsion loop is when lab rats and drug addicts need more and more to achieve the same effect.

One result is what experts call "cognitive overload," resulting in our losing our ability to transfer learning to long-term memory. It’s as if our brains were full cups of water where anything more poured into them spills out. Our minds fill with so much trivia that we lose touch with deeper meanings, and become too distracted to notice more important things in the first place.

Overcoming Internet addiction might be harder to deal with than other addictions. Schwartznov found it so in his life, and it was the same with me when I spent my teen years so addicted to ham radio as WA4PGA that I never dated until my twenties, or otherwise learned basic social skills; I spent all my teen years compulsively tapping out Morse Code.

Ham radio and the Internet are alike in that they are both forms of communication and socialization, plus a little learning content . With this in mind, I remember that the Six Miracles of Nature outlined at https://www.backyardnature.net/j/6/ suggest that the whole evolutionary flow of the Universe is toward ever higher states of interconnected mentality -- in "communication, socialization and learning," we might say.

On a metaphysical level, it's as if the goal of the Universe's evolution trends toward becoming something like a universal brain composed of thinking, feeling beings communicating with one another -- like neurons in a physical brain. The tug in that direction, in my experience, can be almost overwhelming. Well, this Newsletter and these words flow in that current.

A problem with the situation is the inescapable fact that hours spent before an electronic screen are hours not spent sensitizing ourselves to, and learning from, Nature. And Nature's most important influence, it seems to me, is to impart to the disciple reverence for life, diversity, and sustainability.

And just imagine what everyday life could be like if all us thinking, feeling beings were to redirect energies spent feeding our addictions toward championing life, diversity, and sustainability.

*****

Best wishes to all Newsletter readers,

Jim

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