May 17, 2018
RAIN LILIES
This year the rainy season arrived several weeks earlier than normal, breaking the trend of recent years of arriving progressively later. This probably explains the blossoming of some eight-inch-tall (20cm), ornamental flowers planted along the trail to the hut, shown at https://www.backyardnature.net/n/18/180517zy.jpg
The blossoms looked familiar, but the tufts of leaves somehow seemed out of order, so maybe this was a species I'd not seen of a known genus. To help with identification, I tore open a blossom to reveal anatomical features, shown at https://www.backyardnature.net/n/18/180517zz.jpg
First, at the picture's very bottom, notice how the green part constricts and then enlarges. These are the features of a flower with an inferior ovary -- where the petals or petal-like parts and sexual parts arise atop the ovary, not at the ovary's base, as in superior ovaries. This is important because despite these plants looking like members of the Lily Family, species in that family nearly always have superior ovaries, while inferior ovaries are typical of the closely related Amaryllis Family.
So, feeling around in the soil and finding that the leaves and stem arose from bulbs, and seeing that no leaves arose from the stem, or "scape," bearing the single blossom, that the ovary contained numerous ovules instead of a few, that lobes of the corolla-like perianth united at their base into a tube, that the golden anthers were affixed to their white filaments at the middle of their backs ("medianly dorsifixed") -- note the anther lying ±horizontally atop its filament -- and that the stamens were of two lengths, not four, the plant was revealed to be a member of the genus Zephyranthes, of the Amaryllis Family. And we've seen Zephyranthes species before, but only in the wild.
You might enjoy seeing variations on the Zephyranthes theme by reviewing two species encountered in Texas, at https://www.backyardnature.net/n/h/rainlily.htm and https://www.backyardnature.net/n/h/rainlil2.htm and a yellow-flowered one here in the Yucatan, at https://www.backyardnature.net/mexnat/zephyran.htm
All these species are called rain lilies. Our current planted ornamental is, too. It's ZEPHYRANTHES CANDIDA, native to Argentina, Chile and Uruguay. The MissouriBotanicalGarden.Org website for this species describes it as an annual when planted up north, but down here ours have been coming up at the beginning of the rainy season for several years.
You might enjoy reviewing several ornamental Zephyranthes species profiled at the PacificBulbSociety.Org website.
*****
"WILD" YELLOW-OLEANDER'S INLAND FACE
Prettily littering the ground of the one-lane dirt trail on which each morning I jog through the woods,were several yellow, familiar-looking blossoms, as shown at https://www.backyardnature.net/n/18/180517cc.jpg
These looked like blossoms of a wild-growing yellow-oleander species we'd looked at along sandy roads paralleling the beach on the Yucatan's Caribbean coast, but small trees were much branched and formed dense walls along the road, but no such Yellow-Oleander walls were present here. You can see the walls along the coast at https://www.backyardnature.net/yucatan/oleander.htm
These blossoms were falling from a single, tall, slender, rather spindly tree snaking up through a host of other trees and vines, all competing for sunlight. Maybe this was another Yellow-Oleander species...
"Doing the botany," I broke open a flower lengthwise, and saw the typical yellow-oleander flower structure shown at https://www.backyardnature.net/n/18/180517cb.jpg
In that picture, the much-reduced stamens are in the shadows at the very bottom. A closeup of them is at https://www.backyardnature.net/n/18/180517cd.jpg
The anthers are very distinctive. Notice how each stamen's anthers consist of two cells that release their pollen through side openings, and between and above the two cells a pointy, cap-like appendage arises. The stamens in the picture arise at the mouth of the narrow corolla tube, and that opening is lined with many slender, white hairs bending downward. This means that if a pollinator is attracted into the narrow corolla tube by nectar fragrance in the tube's bottom, it'll have a hard time getting out, needing to push against the points of sharp hairs. Having to tarry in the tube, the pollinator is more likely to deposit pollen it's carrying from other flowers.
All these flower features are just like those seen on the Caribbean coast yellow-oleanders, just that the plant bodies bearing the flowers are radically different. However, on Sunday's bike trip to Temozón to buy fruit the same kinds of flowers turned up on tall trees along the road. You can see one starting out below either unbranched or with only a few branches, amid a shaded jumble of other close-pressing trees, bushes and vines, but vigorously branching higher up when it reaches sunlight, at https://www.backyardnature.net/n/18/180517ce.jpg
That tree's upper branches bearing flowers and immature green fruits are seen at https://www.backyardnature.net/n/18/180517cf.jpg
Still thinking this might be a second Yellow-Oleander species, I was surprised when I couldn't find a second species with such flowers listed for the Yucatan. So, they're the same thing, just that their vegetative appearance differs depending on environment.
When we met wild Yellow-Oleanders on the Caribbean, we called them Thevetia gaumeri. Now most authorities appear to have shifted the species to a new genus, calling it CASCABELA GAUMERI. However, the situation is controversial, with some authors including Cascabela within Thevetia, while others accept the two genera as separate. CICY's "Flora of the Yucatan" project now places the species in Cascabela, so that's what I'll use here.
In a paper proposing the separation of the two genera based on morphology, the reasons seem scant to me. They write, "... digitiform suprastaminal appendages and embryos not compressed in Cascabela; reniform fruits and segmented endocarp in Thevetia... "
*****
HORSE-CRIPPLER CACTUS
During my recent camping trip in the highlands east of Saltillo, Coahuila, in northeastern Mexico, on April 5th I started out hiking on a valley floor, and climbed a small mountain that was grassy and scrubby at its base, but forested on top. Toward the top, at ±7000 feet in elevation (2100m), in openings on thin soil atop limestone rock and amid sparse forest of widely spaced pine and junipers, I found the little cactus shown at https://www.backyardnature.net/n/18/180517th.jpg
I was especially happy to see this, for during the previous week when I'd been camping in Amistad National Recreation Area in southwestern Texas along the Mexican border, I'd been looking for a Horse-Crippler Cactus, and this was one of them. Back in the 1980s when I camped regularly in Amistad, I'd often seen Horse-Cripplers, but during this visit I couldn't find a single one. Horse-Cripplers get their name because, instead of producing impressive above-ground bodies, they display only the tops of their flattish heads, and their heads are ±level with the surrounding soil. Any critter not watching where the feet go can easily step on one of these, and you can see that the head is heavily armored with hard, sharp spines.
On this mountaintop, Horse-Cripplers were fairly common. However, the species I remembered from Texas, Homalocephala texensis, had vertically ribbed bodies and bore red flowers, while the bodies of these in Coahuila looked like they consisted of many closely packed little green-chili-peppers, and produced yellow flowers. You can see its flowers closer up at https://www.backyardnature.net/n/18/180517ti.jpg
Spine disposition is an important feature in cactus identification, so a typical cluster of four, purple-tipped, whitish spines is shown at https://www.backyardnature.net/n/18/180517tj.jpg
With such big differences in body structure, these horse-cripplers in Coahuila were obviously a very different species from the one I'd known in Texas. Having two such unrelated species behaving so similarly suggests that presenting oneself as a low-lying, spiny, ±ground-level head can be a good adaptation, one worthy of unrelated species independently evolving the habit -- of undergoing "convergent evolution." In fact, just in Coahuila state five species in four different genera display such a habit, and are known by the Spanish name of Manca Caballo, meaning "horse crippler."
I know this because the excellent, well illustrated, Spanish-language Guía de Cactáceas del Estado de Coahuila by Alfredo Flores is freely available on the Internet in PDF form at http://www.sema.gob.mx/descargas/manuales/cactus.pdf
In that publication our Coahuila horse-cripper reveals itself to be THELOCACTUS RINCONENSIS, endemic just to the Mexican states of Coahuila and Nuevo Leon. The literature reports it as occurring up to 2000 meters in elevation -- Flores's Guía says 1500 -- but the ones I found were at 2100m. At some places within its limited distribution its described as "very abundant," but it's losing ground fast to farming, ranching and urban development. Flores describes its growth rate as very slow.
The species is described as variable in appearance, and little-studied, so I'm glad to offer documentation that at least on one mountaintop east of Saltillo, Coahuila, Horse-Cripplers look like the one in our pictures.
*****
HERBICIDE BOTTLES ALONG THE TRAIL
Lee the ranch's owner gave me a printout of an online article in the Noticias de Yucatán entitled, "El suelo yucateco, envenenado 8,000 veces más de lo permitido: UNAM," translating to, "Yucatan's soil poisoned 8,000 time more than permitted, UNAM (Automonous National University of Mexico, in Mexico City)." The story is short on hard data relating to the Yucatan, but I wasn't surprised that its soil is poisoned. People here use herbicides so habitually that when I visited a Maya friend's home and he mentioned líquido, which in general Spanish means "liquid," everyone around understood that he was talking about herbicide.
Biking back to the ranch along the dirt road through the woods, I'd been noticing where someone had dumped a pile of bottles so, thinking about the article, on my list trip back from Ek Balam I decided to see what the bottles had contained. You can see them lying where I found them at https://www.backyardnature.net/n/18/180517bu.jpg
A close-up of two bottles shows what they contained, at https://www.backyardnature.net/n/18/180517bt.jpg
Both had been full of 2,4-D, the trade name for the compound 2-4-Dichlorophenoxyacetic acid. Back in the 50s when I was a kid on the farm in Kentucky, 2,4-D already was a favorite herbicide. It kills most dicots, such as cockleburs, ragweed, and smartweed, while not harming monocots such as corn, or maize.
Seeing the 2,4-D bottles suggests a further insight into why the Yucatan's Maya are abandoning their traditional cornfields -- their milpas, in which corn has been planted along with vining beans and squash -- in favor of just corn, in the process impoverishing the soil. Beans and squash are dicots, so if you spray 2,4-D on a traditional cornfield containing them, the beans and squash will die. If my suspicion is correct, use of 2,4-D is largely responsible for destroying the milpa system that for thousands of years has sustained corn-planting indigenous communities throughout the Americas.
Normally 2,4-D is thought of as one of the less dangerous chemical pesticides, at least for humans, though different agencies and experts claim different things. The US's Environmental Protection Agency describes 2,4-D as moderately toxic to birds and mammals, slightly toxic to fish and aquatic invertebrates, and practically nontoxic to honeybees. However, other people looking at other data express such concern that 2,4-D currently is not approved for use on lawns and gardens in Denmark, Norway, Kuwait, and the Canadian provinces of Québec and Ontario.
2,4-D is only one of many chemicals being used in prodigious quantities in the Yucatan and elsewhere. In the Yucatan this is especially worrisome because the entire peninsula is a hunk of limestone through which water, instead of filtering through deep soil and/or porous rock, flows through fissures and in underground channels. Much water, then, is filtered very little or none at all.
This calls to mind an observation I made at the end of May, 2015, the day after the first good rain of the rainy season, after a boat trip up the estuary at Río Lagartos. In certain spots the estuary smelled strongly of cow manure, though the wind was not from the ranchlands to the south. I suspected that rainwater from the southern ranchlands around Tizimín arrived in the estuary so quickly via underground rivers, mostly unfiltered, carrying the manure's odor, as well as bacteria and chemicals.
Since the half life of 2,4-D is 6.2 days in aerobic mineral soils and is considered intermediately to highly mobile, 2,4-D sprayed by a rancher around Tizimín several days prior to that first rain would likely have leached into the groundwater, and accompanied the odor of manure I smelled that day in the estuary of Ría Lagartos Biosphere Reserve.
*****
SIGNS OF RAIN
The big news in this area is that this year the rainy season has arrived much earlier than expected. Last Saturday we received about an inch of rain and each day since then powerfully thundering storms have grazed us.
Last Saturday the morning began cloudless, but early on I figured that it would rain. That's because, first of all, as I'd jogged that morning, an enormous black wave of army ants had passed across my trail, and that's always a good sign of rain. Second, many trees were dripping sap from wounded branches, causing dark, greasy-looking spots on the ground, where the previous morning there had been none. Maybe the low pressure system bringing rain was making it easier for sap to flow from the wounds. Finally, a toad on my porch began croaking around noon, despite there being no rain clouds visible.
When I was a kid on the farm in Kentucky my father taught me the signs of rain. His favorite was when tree leaves flipped over, revealing their silvery undersides. Also, he believed that when the Yellow-billed Cuckoo calls, he's predicting rain. In fact, in that area, country folks called Yellow-billed Cuckoos Rain Crows. My grandfather Conrad had a sign for predicting afternoon rains that pup up during the summer: If morning begins with a heavy dew, then no rain, but if there's no dew, rain will come.
*****
FOREST SUCCESSION
From the hut's porch, seated in a classic red, plastic, curve-backed Disfruta Coca-Cola chair next to its matching red table-- disfruta means "enjoy" -- the view across the deep pit is one of a young forest. No tree trunk is thicker than my arm, and the trees rise no higher than the hut's ridge.
The view brings to mind the day I stood atop the water tower seeing that the whole ranch was covered with trees a little lower and paler than those along the property's perimeter. That's because trees on the ranch are younger. Fifteen years ago when the owner bought the property, it had just been burnt in accordance with Maya slash-and-burn technology.
The ranch's yearly burning ended then. Among the weeds covering the ranch the next rainy season were untold numbers of germinating Wild Tamarind seedlings that by the second rainy season mantled the entire ranch with fast-growing, chest-high Wild Tamarind saplings. By the third rainy season the ranch's vegetation already looked like a young forest, but one consisting of little more than Wild Tamarind.
Now, sitting in my red Coca-Cola chair, at eye level from my Coca-Cola seat on the hut's porch I see Whiteseed Manga, Grape Tree, Yucatan Persimmon, Yucatan Caesalpinia, Limestone Senna and other species specially adapted to thin, dry soil atop limestone bedrock. However, I don't see a single ferny-looking, acacia-like Wild Tamarind's leaf. This, despite the forest's canopy being thick with them. That's because during those early days of the forest's formation, young Wild Tamarind trees shaded the ground and sheltered it from drying-out wind. That created a welcoming environment for seeds of many tree species to sprout, but under such conditions Wild Tamarind seedlings can't compete.
So, fifteen years ago, Wild Tamarind was a "pioneer species," a kind of first responder to the awful wound that decades of ranching and yearly burning had inflicted on the natural environment here. Conceivably someday yet other species than what I see now will form a "climax community" here atop my knoll. At that time, the same species forming the canopy will be those emerging as seedlings on the forest floor, and the forest will be "in equilibrium."
I like to sit in the red plastic Coca-Cola chair seeing and thinking about all this -- about the impulse and genius causing the forest irresistibly to evolve toward ever more diverse assemblages of species, with ever more numerous and sophisticated interactions among individuals and species, the forest structure over time ever more complex, investing more and more energy in maintaining its ever more intricately interrelating nutrient cycles and cycles of flowering, fruiting and going dormant, while at the same time always responding to populations of pollinators, hungry herbivores, diseases, all with their own, interrelating and evolving systems, on and on and on...
My mind isn't adequate for grasping more than the fundamentals of what's going on, but I sense that the whole thing is most meaningful to me when I experience it less intellectually than symphonically, and less symphonically than spiritually. Moreover, this forest's basic pattern of development seems to be harmonious with the blossoming and forthcoming of the whole Universe. I think of the forest at teaching how to conduct my own life, because -- as much as anything else I know -- this forest and its universally repeated patterns reveal what the Universal Creative Impulse wishes of its creations.
Forest succession is just one such teaching pattern. There's also the pattern of evolution of Life on Earth from simple to complex, and -- remembering that everything is natural -- the evolution of music from its first bangings to Beethoven and Bach, of the history of computer science from abacus to today's supercomputers, the history of any large, complex human community from its first pioneer no now, on and on.
Teaching patterns are everywhere. One just needs a red plastic Coke chair, or something like it, and the will to spend time paying attention, and reflecting on what's beheld.
*****
Best wishes to all Newsletter readers,
Jim
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