February 20, 2011

BLACK-HEADED TROGON
Trogons are chunky, small-beaked, tropical birds a little smaller than Pigeons, and much more boldly patterned. They tend to perch unmoving in deep shadows, occasionally flitting out and quickly nabbing a fruit, then returning to the shadows to eat. Our common trogon here is the Violaceous Trogon, shown at https://www.backyardnature.net/yucatan/v-trogon.htm.

In that picture, notice the tail's "bar coding" -- a few large white spots separated by more numerous, narrow "zebra stripes." Compare that pattern with what's on the tail of the trogon seen this week at https://www.backyardnature.net/n/11/110220tr.jpg.

The big white spots are about the same but narrow zebra stripes are practically few.

Among trogons, of which nine are listed for Mexico (including the famous Resplendent Quetzal, which is a trogon with a very long tail), tail bar-coding is important, and in the field the presence or absence of zebra lines is the main way to distinguish this week's Black-headed from the Violaceous.

The eyerings also differ between the species. In the picture you might notice a very slight blue tinge to the bird's eyering. The male Violaceous' eyering is yellow, while the female Violaceous' eyering is broken into two white crescents, one before and one behind the eye. Violaceouses are about an inch smaller, too, but size differences are hard to judge in the field.

Most trogon species are much more different from one another than these two are. When you see two such similar species you can guess that they are very closely related, possibly "sister species" that have arisen from a common ancestral species.

Black-headed Trogons are distributed from southeastern Mexico south to northern Costa Rica. The bird in the picture was perched on a spiny Bougainvillea stem, a gob of fig fruit stuck to his lower mandible, for he was helping finish off this season's crop of figs from the Chinese Banyan in which last week we saw the toucans. Now the figs are eaten up and the toucans seem to be gone.

Actually several bird populations seem to have shifted about lately. For the last year White-winged Doves were uncommon around the Hacienda, while White-tipped ones were seen daily. Suddenly White-wings are abundant, constantly cooing their Who-cooks-for- yoooooo... ? call. Similarly all year, Blue-crowned Motmots appeared here only sporadically, while Turquoise-browed Motmots were seen every day. For the last couple of weeks, Blue-crowns have outnumbered Turquoise-brows.

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TROPICAL PANICGRASS
Looking at the surrounding central Yucatán landscape from a slight elevation -- from atop a pyramid or bridge, for instance -- from horizon to horizon you see a fairly flat plane. Up close, however, you see that the plane's surface is very irregular with endless little mounds and depressions the size of a house or basketball court.

Soil on risings is thin and red, and easily erodes into depressions, where the soil can be several meters deep, and dark. The red soil, poor in organic matter, holds little moisture and is less nutrient-rich than black soil in the depressions, which holds moisture longer, and is better for gardening. When the Maya build their raised beds, called "eras," they fill them with black soil, which may have to be carried a good distance.

The other day as I dug a knee-deep hole into black soil, collecting it for potting plants, a breeze blew into my pit the light-weight, diffuse item shown at https://www.backyardnature.net/n/11/110220pc.jpg.

That's a grass's flower/fruit cluster, or inflorescence. About twenty feet upwind I saw the drying-out cluster of grass stems the inflorescence had blown from. You can see those dying-back stems at https://www.backyardnature.net/n/11/110220pd.jpg.

With a handlens I looked at the tiny "floret" shown at https://www.backyardnature.net/n/11/110220pe.jpg.

Florets are grass flowers. The one in the picture is 1mm long (±1/25th of an inch) and is unusually small. In fact one name for the plant is Smallflowered Panicgrass, though the name Tropical Panicgrass seems to be more common. It's PANICUM TRICHOIDES, with members of the genus Panicum collectively being referred to as panicgrasses -- because species in that genus array their flowers in panicle-type inflorescences.

So, why did this grass evolve such tiny flowers in such diffuse flower clusters? The inflorescence that blew into my black-dirt hole tells us the answer. When inflorescences easily snap from their stems, wind blows them across fields, transporting the tiny fruit-grains to new places. The panicle's diffuse form and tiny flowers is a wind-dissemination adaptation similar to that practiced by tumbleweed, except that tumbling tumbleweed consists of the whole plant rolling across the land, while here we just have the inflorescence.

Tropical Panicgrass appears to be native tropical American, but now it's found as a weed in disturbed tropical areas nearly worldwide. I was able to identify it only because it's included in the online Flora of North America, for it's been documented growing in southern Texas.

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A SHRUB ACALYPHA
Acalypha is a genus in the Poinsettia or Euphorbia Family, the Euphorbiaceae. The genus is worth knowing because in the Americas you run into it frequently, and it includes some important ornamentals. About 450 species are assigned to it, mostly tropical and subtropical shrubs, trees and herbs. Weakley's Flora of the Southern and Mid-Atlantic States lists seven species for that area, naming them copperleafs. Also the name Three-seeded Mercury is given to a weedy, herbaceous Acalypha growing in much of that area.

Nowadays in central Yucatán a common, much branching, shrubby member of the genus, ACALYPHA LEPTOPODA, is conspicuously flowering at woods edges and along trails. There's no common English name for the plant, so I just call it Acalypha. It's Ch'ilib Tux or Sak Kip in Maya. Its seven-ft-high (2m), slender, arching branches are shown avalanching into an open at https://www.backyardnature.net/n/11/110220ac.jpg.

Its branches bear old leaves, newly sprouting leaves, long, slender spikes of male flowers and short, blunt spikes of female flowers with red styles, as shown at https://www.backyardnature.net/n/11/110220ad.jpg.

A close-up of a female spike with its red styles is at https://www.backyardnature.net/n/11/110220ae.jpg.

In that picture notice the saucer-like, several-toothed, greenish "foliaceous bracts," or modified leaves, doing calyx service below the ovaries. Conspicuous foliaceous bracts subtending ovaries is one of the main field marks for the genus Acalypha.

The male spikes, once their pollen loads have been released, fall off, but of course the female flowers' ovaries remain on the branches, growing and maturing until they become fruits bearing viable seeds. You can see two semi-matured fruits with their much-enlarged foliaceous bracts beneath them at https://www.backyardnature.net/n/11/110220af.jpg.

Three-lobed ovaries are typical of the Euphorbia Family. The vast majority of ovaries of dicot plants have parts in fours or fives, or multiples thereof, not three.

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AECHMEA BROMELIAD BRACTS
We've examined our big Aechmea bromeliads twice, most recently last May when they were flowering, as seen at https://www.backyardnature.net/yucatan/aechmea.htm.

Now the Aechmeas are issuing very handsome spears of immature flower clusters, or inflorescences, shown at https://www.backyardnature.net/n/11/110220a2.jpg.

That spear is about five feet tall (1.5m), so these spikes are striking presences here. Normally Aechmeas live on tree branches and in tree forks, but often they fall to the ground and seem to do well there, too. You can see the immature inflorescence close up at https://www.backyardnature.net/n/11/110220a3.jpg.

It's something how early morning sunlight catches in the pinkish bracts.

Anyway, once again we come to bracts doing something special, as was the case above with the Acalypha. Fact is, if you do much botanizing, eventually you just have to recognize that many plants bear bracts -- which are modified leaves -- and it's worthwhile to be able to recognize them and figure out what they're doing. The foliaceous bracts on the above Acalypha were serving as oversized calyxes possibly highlighting the mature fruits, causing them to be more visible to whatever animal disseminates them. That's just a guess. You can find bracts doing all kinds of things.

For example, the Aechmea's stiff, sharp-pointed, scoop-shaped bracts clearly dissuade animals from eating the immature flowers. Look at the defense offered by sharp bracts and sepal tips at https://www.backyardnature.net/n/11/110220a4.jpg.

Also, you can imagine that immature flowers inside the wrap-around bracts are protected from cold night air even as now in early morning the sun's first rays heat up the bracts' interior. The extra warmth helps flowers mature faster, since heat generally speeds up biochemical reactions. The bracts are even reddish, protecting fragile genetic material in the developing flowers from being damaged by unfiltered sunlight.

In fact, whenever you see flowers or fruits in any situation it's fun to tarry awhile to figure out how the plant is protecting its most important parts -- its reproductive organs. Is it with simple spines, camouflage, sticky hairs, hard shells, bitter or deadly or maybe hallucinogenic chemicals? Among wild plants nearly always you find one or more defensive mechanism. With domesticated plants often the defenses have been removed by selective breeding.

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INKY-CAP ON A TWIG
Though parts of humid Mexico are mushroom wonderlands, the Yucatán is relatively mushroom impoverished. Surely it has to do with the severe, six-month-long dry season we have, and the thin, organic-matter-poor soil. Here in the heart of the dry season, mushrooms are particularly rare.

So, the other day I was especially glad to see three little parasols arising from the downed branch shown at https://www.backyardnature.net/n/11/110220cp.jpg.

They were only about two inches tall (5cm), and I suspect that they are emerging now because last week we received over an inch (±3cm) of rain -- very unusual for February in the Yucatán. Fungal mycelium must have been lying dormant inside the dry, fallen tree branch so when the rain came the mycelium went into action forming fruiting bodies -- which is what mushrooms are.

No guide to the mushrooms of the Yucatán exists so usually when you find a fungus you can't identify it. The ones on the twig, however, I could see at first glance, belonged to the inky-cap group of species.

Notice the dark fringe on the brown cap at the right. That cap has begun to melt along its edges -- to "deliquesce." The middle cap has progressed a bit further, starting to droop and get raggedy, and the cap at the left has practically collapsed into a formless blob atop its more resilient white stalk. That's what inky-caps do. They're fragile mushrooms whose caps melt soon after forming. The inky fluid that results bears millions of spores, and smears easily onto whatever passes by, including insect legs that carry the spores to germinate far away.

On the Internet I can't find pictures matching these. I'm guessing it's the genus Coprinopsis, but who knows?

Somehow the name isn't too important, especially after I got to study and admire the cap's top, suggesting some kind of celestial explosion or genesis, shown at https://www.backyardnature.net/n/11/110220cq.jpg.

Beneath the cap I discovered the lovely radiation seen at https://www.backyardnature.net/n/11/110220cr.jpg.

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A WONDERFUL MUSHROOM-IDENTIFYING SITE
While trying to identify the above inky-cap I found that the free, online MycoKey mushroom-identification website in Denmark has added new features making mushroom IDing even more fun than before. Mainly, as you start keying out your unknown mushroom by supplying the key with details about your find, such as cap width, how gills attach to the stem, spore color and such, a drawing of a mushroom gradually changes, exhibiting the features you're describing. If you say the cap is red, the drawing's cap turns red.

The species keyed out at MycoKey are Northern European. However, North America and Europe share so many species, and a large number of genera, that even North Americans can benefit from using this site.

The new edition of the MycoKey website can be accessed here.  

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RESIN
Walking through Pisté I pass a large Cedro tree, Cedrela odorata, a species we've already profiled at https://www.backyardnature.net/n/w/cedro.htm.

The tree in Pisté caught my attention because its trunk had been wounded, and from the wounds copious quantities of resin had issued, congealing into amber-colored, semi-hardened masses the consistency of hard, waxy cheese. You can see all this at shown at https://www.backyardnature.net/n/11/110220rs.jpg.

Why do certain trees, such as pines, Araucarias and our Cedros, issue resin when wounded, while most trees don't, at least not in noticeable quantities?

Chemically, resins consist mostly of hydrocarbon waste products -- waste from the plants' biological processes such as respiration, photosynthesis, glycolysis, and the like. For this reason it's sometimes resin is seen as little more than an incidental, unavoidable byproduct of life, like feces among animals.

However, sometimes resin definitely helps plants they exude from. They may contain compounds that repel, confuse or kill a wide range of plant-eating invertebrate animals, especially insects, and disease organisms. Also compounds that evaporate from the drying resin -- volatile phenolic compounds -- have been documented attracting organisms that parasitize or prey upon herbivores that attack the plant.

In the special case of our Cedro tree an especially aromatic resin suffuses the tree's heartwood famously repelling insects and bestowing the wood with an intense odor like that of northern cedars and junipers. Our Cedros are not closely related to cedars and junipers, however, Cedros being angiosperms and cedars and junipers being gymnosperms.

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WAITING FOR TOUCANS
In late afternoon a friend and I sit in grass beside a Chinese Banyan hoping toucans will come and feed. The ground is chilly and moist but the grass is emerald green, the kind of greenness possible only with lots of watering and heat. In the sunlight, translucent grassblades glow almost violently while beneath them starkly contrasting black shadows impart to the lawn a vivid three-dimensionality. The grassblades' underlying darkness is like a deep contrabass pulsating beneath excited violin soarings.

The odor of crushed grass pools around us. An unhurried late afternoon breeze gathers into itself odors of moist air, of damp, moldy soil, and lemony-smelling Lemoncilla flowers, their waxy-white little blossoms nestled among darkly shadowed tree-branches. The breeze mingles these perfumes with our own oily odor of skin sizzling in sunlight.

I look at my friend between the sun and me, soft moist flesh as black silhouette silver-rimmed with sharp sun-sheen, round nose-tip, sloped forehead, angled cheekbone, plunge of neck, all black with scorching silver halo, and this silhouette moves, something very alive here beside me, alive and unfathomed. I put my hand against the sun to see, but sun-splinters splatter between fingers, fire-edged silhouetted fingers, light flashing, shifting, stabbing deep grass, slicing Limoncillo fragrance, jabbing into my eyes and I look away.

Green, green the grass, looking into the grass, not really interested in toucans, just need the grass to stay as it is, just need me to stay right here, nothing to change, keep this moment steady and quiet like a grassblade-tip dewdrop unwilling to fall.

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Best wishes to all Newsletter readers,

Jim