JIM CONRAD'S
NATURALIST NEWSLETTER
Issued from Hacienda Chichen Resort
adjoining Chichén Itzá Ruins in
YUCATÁN, MÉXICO

January 22, 2012

HUNGRY SQUIRREL
Nowadays on most early mornings just as the sun breaks over the horizon an endemic Yucatan Gray Squirrel, SCIURUS YUCATANENSIS, climbs into a tree near the hut and perches awhile nibbling fruits, as shown at http://www.backyardnature.net/n/12/120122sq.jpg.

The tree he climbs is an abundant, almost-weedy species that in most of Mexico is called Guácima, though in Querétaro we knew it as Aquiche, and the Yucatán Maya call it Pixoy. It's Guazuma ulmifolia of the Cacao (Chocolate Tree) Family, the Sterculiaceae. Nowadays because of the dry season many Pixoys have lost nearly all their leaves, but their branches still bear abundant, marble-sized, semi-woody, bumpy-surfaced fruits. The tough fruits contain just enough sweet goo to entice anyone with a sweet tooth to gnaw into them, thus freeing the seeds for dispersal. Good fruit pictures can be seen on our Pixoy page at http://www.backyardnature.net/q/guazuma.htm.

So, what's the story here? The story is the mere fact that a Yucatan Gray Squirrel is being documented eating fruits of Guazuma ulmifolia. Down here relatively little fieldwork has been done on most plants and animals, so such documentation is valuable to future ecologists and book writers trying to piece together the life histories of organisms found here.

To that future investigator... here it is!

*****

HUNGRY BIRDS
In fact, last Monday morning, everything seemed hungry, and I'm not sure why. Maybe it was because it was such a perfect, moist, warm, springy morning (despite all the dry-season-falling leaves) that many organisms, including myself, just felt like gorging on everything.

For instance, during my morning walk a Golden-fronted Woodpecker with his seasonally spectacularly red belly flew into a Wild Papaya and gave a maturing fruit the eye before stabbing into its orange flesh, as seen at http://www.backyardnature.net/n/12/120122b2.jpg.

In a leafless, super-prolifically fruiting Cow-Itch tree (Urera baccifera) an Altamira Oriole took his time stuffing himself with BB-size fruits, as shown at http://www.backyardnature.net/n/12/120122b1.jpg.

Another Altamira Oriole perched atop the highest bouquet of a flowering African Tulip Tree dipping his beak into pooled water or maybe preying on flower bugs, the blossoms' yellow-orangeness perfectly complementing the oriole's bright plumage, as seen at http://www.backyardnature.net/n/12/120122b4.jpg.

Even if you're familiar with Mexican birds you may not recognize the species in full adult-male plumage making a head-blurring stab into fruits of the dry-season leafless Gumbo-Limbo tree (Bursera simaruba) at http://www.backyardnature.net/n/12/120122b3.jpg.

That bird's appearance is confusing because he's turned his head upside-down in order to get at something among the fruits. He's a Rose-throated Becard, with his rosy throat turned skywards.

*****

A PHOTOGENIC BIRDNEST
Biking the little road south of Pisté, as I passed a Huano fan-palm at the edge of the road and in front of a family's thatch-roofed hut, I noticed what's stuck to the underside of the palm's big frond shown at http://www.backyardnature.net/n/12/120122bn.jpg.

It's a birdnest, and since it's a pendulous one the best bet is that it belongs to one of our several species of oriole. In fact, last summer down at Marcia's on the coast we looked at a Black-cowled Oriole's nest suspended beneath a palm's frond and it looked like this one. It also was constructed of stiff fibers teased from palm fronds, and situated low and surprisingly near frequent human activity and noise-making, so I'm betting that that's what this one is. Black-cowled Orioles are common here as well as along the eastern coast.

The most striking feature of this nest, though, was its architecturally arresting location. One can almost suspect that this oriole mama enjoyed an exceptionally refined esthetic sense.

*****

A WOODY MORNING-GLORY
We've already met the Morning-glory Tree, IPOMOEA CARNEA, planted in gardens. You can see one in full flower along the Paseo Montejo in Mérida, and a white-flowered form in a garden nearby in Pisté at http://www.backyardnature.net/yucatan/tree-m-g.htm.

Ipomoea carneas are native, wild-growing plants here, and nowadays they're flowering. Their pinkish, saucer-size blossoms are especially conspicuous now because most morning-glory vines are past flowering, though certainly not all. You can see a wild one emerging from a rock outcrop beside the little road between Pisté and Yaxuná to the south at http://www.backyardnature.net/n/12/120122mg.jpg.

A shot of a blossom's face showing a dark center and the tops of two anthers poking from the throat is at http://www.backyardnature.net/n/12/120122mh.jpg.

A longitudinal section showing the spherical stigma head among five stamens of very different heights is at http://www.backyardnature.net/n/12/120122mi.jpg.

A view of a leaf's soft, velvety undersides is at http://www.backyardnature.net/n/12/120122mj.jpg.

Leaves on planted Morning-glory Trees I've seen have been narrower and more slenderly long-pointed than these, plus the ones I've seen planted are really bushes, while the ones growing in the woods here have woody, bushy bases, but their branches elongate until they become definitely vine-like.

That's because two different subspecies are involved. The planted shrubs with long-pointed leaves are Ipomoea carnea ssp. fistulosa; our currently flowering, wild, vine-tending ones with more heart-shaped leaves and with branches elongating and becoming viney, is IPOMOEA CARNEA ssp. CARNEA. In English I think of the later viny one as the "Vining Tree Morning-Glory."

I. carnea ssp. fistulosa, the planted bush, is native from southern Texas all through Mexico and Central America deep into tropical South America. In many tropical and subtropical countries it's escaped cultivation to become a serious invasive species, especially in low-lying areas along waterways. I. carnea ssp. carnea, our wild, vine-tending one, occurs only from southern Mexico south into South America, and it inhabits drier habitats than ssp. fistulosa.

As with many morning-glory species, the seeds of both Ipomoea carnea subspecies are toxic.

*****

ELEPHANT GRASS
In an overgrown abandoned lot at a street corner in Pisté, 12-ft-tall (3.7m) bunches of grass are surprisingly green here in the dry season, as shown at http://www.backyardnature.net/n/12/120122ps.jpg.

Overtopping the stems and blades the slender, spikelike inflorescences bend in the wind, as seen at http://www.backyardnature.net/n/12/120122pt.jpg.

The slender, spikelike inflorescences are very unlike like the broad, feathery panicles of Pampas-Grass, Giant Reed or any of the other very large ornamental clump-grasses, and the stems and leaves are too broad and stiffly erect to be similar to the Sand Cordgrass we saw on the coast this summer. Fact is, if you know your grasses, the slender, very fuzzy inflorescences shown in the last picture could belong to one of the North's abundantly weedy foxtail grasses, though who has ever seen a 12-ft-tall foxtail grass? The close-up of some bristle-based florets arising from their hairy rachis seems to support the foxtail theory at http://www.backyardnature.net/n/12/120122pu.jpg.

However, when you thump a mature head of the grass in the picture, something happens proving that this isn't a foxtail grass: When foxtail grass flowers come off their rachis, just the basic oval flower departs while the stiff bristles remain behind on the rachis. When flowers in the picture fall off, the bristles go with the flowers. We don't have a giant foxtail grass here.

What we do have is a grass originally from Zimbabwe in subtropical Africa, but now planted and escaped as a weedy invasive in most of the world's tropical and subtropical countries. It's PENNISETUM PURPUREUM, among whose many English names Elephant Grass and Napier Grass seem to be the most commonly used. One reason the species is planted so broadly is that it produces a very extensive root system, so it survives droughts as well as dry seasons like ours, and heavy grazing. Also when provided with adequate water and fertilizer it provides an enormous amount of plant bulk for hay and silage.

In fact, an FAO page on the species describes it as one of the "most valuable forage, soilage and silage crops in the wet tropics." A 1978 study found that 2½ acres (1ha) of Elephant Grass could provide enough forage to produce three tons of live-weight gain in Zebu-type cattle.

So, at that rather seedy looking street corner in Pisté, what at first glance is nothing more than an overgrown, abandoned lot turns out to be a refuge for one of the world's most useful and productive grasses.

*****

GRASS LIGULES
Elephant Grasses are so large that some of its anatomical features that in smaller species are too small to draw attention are very apparent. For example, take a look at Elephant Grass's "ligules" at http://www.backyardnature.net/n/12/120122pv.jpg.

In that picture the vertically slanted cylinder is the grass's stem, or "culm," while the flatish, pale item curving off horizontally to the right is the leaf blade. The fencelike row of slender, stiff, sharp hairs arising where the blade meets the culm is the ligule.

Not all grasses have ligules. Ligules come in two basic types: hairy like ours, or as thin, papery sometimes cellophane-like walls. Ligules can be very short or long. During grass identification, ligules can be important because species within a genus tend to have the same basic ligule type.

What are ligules for? Obviously they're not critically important, because many grass species don't have them.

For one thing, imagine a stem-eating bug on the leaf in the picture, approaching the stem. If the bug wants to burrow into the stem, the Elephant Grass's sharp- pointed ligule hairs will provide at least some protection. Ligules of the cellophane wall type might keep disease organisms gathering at the juncture of blade and stem from infecting the stem.

*****

YELLOW ROADSIDES
Nowadays the road south of Pisté toward Yaxuná is resplendent with a yellow-flowered, weedy wildflower sometimes called Sunflower Goldeneye, Viguiera dentata. Our page examening that species is at http://www.backyardnature.net/yucatan/viguiera.htm.

You can see how the yellowness just stretches on and on at http://www.backyardnature.net/n/12/120122vv.jpg.

*****

DEAD-MAN'S FINGERS
On the same moldering pile of firewood on which we've found slime molds and a germinating Catasetum orchid with white roots, there's the curious object shown at http://www.backyardnature.net/n/12/120122fu.jpg.

At the end of the rainy season the object was firm and smoothly surfaced. Then it became hard and brittle, and nowadays it's collapsing upon itself, with its "skin" splitting and cracking as shown. It stands 2.8 inches tall, (7cm), is hairless and grows from disintegrating wood.

This is a Dead-Man's Finger, XYLARIA POLYMORPHA, a member of the Ascomycetes. Actually, the polymorpha needs to be in quotation marks because the species' taxonomy is so poorly understood that there's a good chance it's not really the polymorpha species. However, at this time, for us non-experts, that's the best name to use. As Michael Kuo at MushroomExpert.Com says of this group, "Even with identifiable specimens in hand, there is no getting around the fact that microscopic analysis is frequently necessary for accurate Xylaria identification -- which leads many collectors to label their collections of fat specimens "Xylaria polymorpha" and their skinny collections "Xylaria hypoxylon," since these are species frequently included in field guides. Ours is "fat."

A cross section view of our Dead-Man's Finger -- the whole thing is technically known as a stroma -- is shown at http://www.backyardnature.net/n/12/120122fv.jpg.

If that were a puffball, which is a fungus in a completely different phylum, I'd interpret the spongy material constituting nearly all the interior as tissue that later would mature into a mass of spores. However, these are Ascomycota fungi that produce spores stacked in a single row inside microscopic tubes called asci (singular ascus) packed closely side by side. The spores are shot from the ascus tips.

On the Internet I learn that the stroma's "filler material" in the above photograph is known as pseudoparenchyma. It serves as a storage reserve of nutrients and water. The little cuplike items along the perimeter are perithecia. The insides of the perithecia are lined with microscopic, spore-bearing asci stacked closely side by side.

Members of the genus Xylaria decompose wood or plant debris. It's typical for the stromata (plural for stroma) to become black and hard at maturity, like charcoal.

*****

A TOMATO FLOWER'S CIRCADIAN RHYTHM
Circadian rhythms are daily cycles of activity displayed by many kinds of organisms. If you experience jetlag when traveling across time zones you're feeling the effect of your own waking/sleeping circadian rhythm. I've grown tomatoes ever since I was a kid but it wasn't until this week when I was paying special attention to a certain flower (more below) that I realized that tomato flowers have their own circadian rhythm governing their openings and closings.

To be sure I was seeing it, in the very dim light of the evening of the day when I first noticed what was happening I took a picture of my flower, along with some neighbors, that I knew had been open all day. The next morning I photographed the same flowers fully reopened. The late-dusk/early morning shots are shown at http://www.backyardnature.net/n/12/120122x2.jpg.

Until now I'd assumed that closed flowers seen in the evening were just young blossoms not yet open, and if there were no open flowers, then it was because all the pollinated ones had fallen off. It's amazing just how unobservant a person can be, especially with regard to ordinary, everyday events.

What a lesson the tomato flower teaches.

*****

TOMATO FLOWER
Last year a visitor brought me four kinds of gourmet tomatoes so I could grow my own plants from the seeds. There was a large, yellow tomato, two small but very tasty kinds, and a smallish one that was blackish purple. I was soon to leave for the coast so I planned to sow them when I got to Marcia's. I'd forgotten that Marcia's sandbar had no soil, though, and I never did recruit enough people to pee on the compost heap to make that work right, so last summer I just did without homegrown tomatoes.

In a way, though, it was right for the project to fail. For, the last time I saw the visitor who gave me the seeds we'd been upset with one another. It was a failed relationship, and now my tomato growing project sprung from that relationship had failed, too. What did I expect?

Still, as soon as I returned to the hacienda at the end of October, I planted the tomato seeds. They germinated nicely, each seed first sending up two little rabbit-ear cotyledons, then hairy, crinkly sprouts emerged from between the cotyledons. Eventually each seedling got put into its own pot, where for weeks each day each one grew a little. It was good watching them grow but, to be honest, I couldn't look at them without darkly remembering the spoiled relationship.

Eventually I built a trellis for them to grow up and transferred each plant to the ground below it. I mixed compost into the soil around them and the vines turned dark green, got ropy-thick and sprouted enormous leaves that if you just barely touched issued pungent tomato-plant odor into the morning air. Every plant seemed about to burst with vigor and good intent.

This week the first flower appeared. It's shown at http://www.backyardnature.net/n/12/120122tm.jpg.

I've sat a long time looking at that flower, its self- confident, swooped-back, yellow petals, its strange- looking, joined-by-their-margins anthers dribbling pollen from pores at downward-directed anther tips, and the long, silvery, rather haphazardly arrayed hairs. How could such a tender, perfect presence arise from such a depressing relationship?

Is reality like two people irresistibly drawn together who then hurt one another, or like a seed that germinates into a plant that grows and evolves, until one day you have an exquisite little flower? This week, with the plants outside the hut door putting on more and more flowers every day and stretching, stretching toward the sky, I've thought about that a lot. Here's what I've decided:

It's both. It's just that damaged feelings are a subset of the greater paradigm of the vivacious tomato seedling.

I mean, even the tomato flower's gorgeous yellow corolla must shrivel, turn brown and fall away (exactly like our relationship!) before the ovary expands, grows and ripens to eventually become a tomato. And then the tomato must be eaten for its destiny to be fulfilled (vanishing like our relationship!), and then the vine itself will die (die!). But the impulse that brought the tomato vine about in the first place (and draws people together) will continue and somehow, I suspect, be even more vital in the future than before.

Yin, yang, ever dancing through time and space, generating broken hearts and tomatoes so lush and poignantly alive with promise that one must cry beholding it. And, yin, yang, ever dancing through time and space, and you must see the humor in it all, the need to laugh uproariously at the whole thing, if you are to get through this life with any semblance of dignity.

*****

Best wishes to all Newsletter readers,

Jim

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