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

AUGUST 14, 2016

*****

DOUBLE-DECKER MILLIPEDE
On the outside washing trough, one millipede perched atop another, looking like a double-decker about an inch long (25mm), shown at http://www.backyardnature.net/n/16/160814mp.jpg

I figured that they were mating. When I first saw them, the head end of the one on top was curved over the bottom one's side until the bottoms of their head-areas pressed against one another; It looked like one was nibbling at the throat of the other. Their rear ends didn't seem to be doing anything. In the above picture, they'd just stopped the "nibbling." You can see them just looking around, and have a better view of the armor atop each body segment, at http://www.backyardnature.net/n/16/160814mq.jpg

But, had that "nibbling" really been millipede sex? On the Internet I learned that among millipedes there are rainbows of mating structures and mating styles. In some millipede types, males deposit packets of sperm called spermatophores, which females pick up and insert where they're needed. In all other millipede groups, males bear one or two pairs of modified legs, called gonopods, with which sperm are transferred to the female. Gonopod location varies between groups. In some they're at the rear of the body, but in the vast majority of species they're on the seventh body segment from the front. Some species reproduce without sex -- parthenogenetically -- having few, if any, males.

On the Wiipedia Millipede Page I read that among the vast majority of millipede types, copulation occurs with the two individuals facing one another. To get the female receptive, the male may tap the female with his antennae, run along her back, offer edible glandular secretions, or, in the case of some pill-millipedes, stridulate, or "chirp." While copulation is taking place, in most millipede types, the male positions his seventh segment in front of the female's third segment.

So, I figure that the throat-nibbling I'd seen was a case of the twisted-around male getting or having his seventh segment in position against the female's third, and that it was millipede sex, or almost sex, before I disturbed them.

But, what kind of millipede among the approximately 12,000 known species do we have? I had a head start on the issue because back in Texas we found a millipede of very similar structure and size, which volunteer Bea in Ontario identified to genus level, shown at http://www.backyardnature.net/n/a/milliped.htm

The Texas millipede belonged to the Family Eurymerodesmidae so I began by looking for common millipede species in that family occurring in the Yucatan. Two very similar, very common, invasive "weedy" species very similar to those in our photos turned up. One was Orthoorpha coarctata, the other Oxidus gracilis.

The main difference between the two species visible without dissection is that on Oxidus gracilis the pale, backward-pointed, ear-like things (the lateral keels or "paranota") on the sides of each mid-body segment is proportionally longer and pointier than on Orthoorpha coarctata. On that shaky basis, I'm guessing that what's in our photos is OXIDUS GRACILIS, often known as the Greenhouse, Hothouse, Short-flange, or Garden Millipede.

Greenhouse Millipedes are thought to be native to Japan but they've been introduced practically worldwide. In the tropics they roam the ground, while in the temperate zone they prefer greenhouses. Around the Hacienda, at least during the rainy season, they're very common.

Most millipedes feed on decomposing vegetation, feces, or soil organic matter, helping in the decomposition of plant litter, and I'd guess that that's what ours are doing. At the Diplopoda.Org website the point is made that in the tropics where earthworm populations are low, millipedes play an important role helping microbes decompose leaf litter.

*****

SILKLEAF
Along a weedy trail in the Hacienda's woods an herb about a foot tall currently bears one or a few clusters of white flowers above relatively large, heart-shaped leaves, as shown at http://www.backyardnature.net/n/16/160814lg.jpg

Wildflower admirers might recognize the leaves as typical of certain members of the Composite or Daisy Family, the Compositae, such as the sunflowers and cockleburs, plus the flowers are a little like those of the eupatoriums, also in the Composite Family. Up close we see flowers that are definitely Composite Family, at http://www.backyardnature.net/n/16/160814lh.jpg

One Composite Family field mark obvious here is that each flower's five blackish anthers are united at their sides into cylinders surrounding the ovary's wishbone-shaped style. Also, the many flowers are clustered tightly together into a head, or capitulum, subtended by leafy bracts forming the capitulum's "involucre." A look at the involucre is shown at http://www.backyardnature.net/n/16/160814li.jpg

Among Composite Family involucres, you seldom see such a loose arrangement of overlapping, leaf-like bracts, so this is an important field mark. If you look much closer at the individual flowers in the head, the "florets," other good features appear, as shown at http://www.backyardnature.net/n/16/160814lj.jpg

Among the composites, a very important field mark always is the floret's pappus -- the structure that may or may not exist where the corolla's base connects with the cypsela-type fruit. In the above picture, the floret at the center-left seems set into a crown-like structure atop the cypsela, and that's exactly the kind of pappus this one is described as having, a "coroniform," one very unlike the white hairs and stiff bristles more commonly seen in other species, so this is a great field mark.

With such distinctive features, it was easy to figure out that this was LAGASCEA MOLLIS, a common weed throughout nearly the entire tropical world. It's thought to be native of Mexico and Central America. Among its English names, Silkleaf may be the most commonly encountered

Silkleaf is fairly common here in weedy areas, and often you see several individual plants forming a small community. A research paper by Elizabeth Murillo and others, available on the Internet, explains why that might be: Silkleafs are "allelopathic." That means that they produce chemicals that retard the growth of other plants around them. Murillo's study found that Silkleaf extracts have a "significant effect on cellular division and radicular growth" (early root growth) on oat seedlings. Since oat plants are grasses, this raises the suspicion that Silkleaf might not be the best weed to have in fields of rice, corn, sugarcane, wheat and rye, which are all grasses.

*****

CAT'S-TONGUE
Right beside the hut door, a weed I didn't pull up because I wanted to see what it was, has begun flowering and fruiting, and it was worth waiting for. You can see it leaning into the sunlight so that I see it when I look out the door at http://www.backyardnature.net/n/16/160814pv.jpg

The plant's opposite leaves (two at each stem node), the curve-tipped flower clusters and the purplish flowers all suggest the Verbena Family. A closer look at the five-lobed, slightly asymmetrical corollas and shallowly toothed leaves increases the impression, as shown at http://www.backyardnature.net/n/16/160814pw.jpg

A side view of a flower is at http://www.backyardnature.net/n/16/160814px.jpg

A peep into the blossom's throat shows only two stamens, but two more are hidden lower down the corolla tube, and that's just like the Verbena Family, seen at http://www.backyardnature.net/n/16/160814py.jpg

However, the bladder-like pods that develop as soon as the flowers are pollinated and the corollas fall off are unusual and unlike other members of that family I can recall, seen at http://www.backyardnature.net/n/16/160814pu.jpg

If you tear away one side of a pods, the fruit revealed inside is about as weirdly shaped as you could want, shown at http://www.backyardnature.net/n/16/160814pz.jpg

The literature describes the mature fruit of this species as a pair of prickly nutlets contained within the persistent calyx. Also, the fruiting calyx is reported as bearing hooked hairs that cling readily to passing my creatures. If that's the case, what do the fruit's prickles seen in our photo do? From what I can see, one of their jobs is to keep the bladder from collapsing as the fruit matures.

This is PRIVA LAPPULACEA, in at least one publication referred to as Cat's-tongue, found throughout the American tropics, extending north as far as southern Texas and Florida. In Mexico it's reported as being an "aggressive and dangerous weed" mainly in tree plantations and orchards. The online Biblioteca Digital de la Medicina Tradicional Mexicana says that traditionally a tea of Cat's-tongue along with the spiny Ortiga is drunk for the infirmity bomaje, which is a kind of hip pain.

*****

TROPICAL CRABGRASS
In thin soil atop limestone bedrock, along a weedy path through the Hacienda's woods, a cluster of grass flowers caught my attention looking exactly like a flowering head of the North's Common Crabgrass, Digitaria sanguinalis. You can see what I mean at http://www.backyardnature.net/n/16/160814dg.jpg

Crabgrass arrays its spikelets in a few narrow, spike-like racemes radiating from the top of a stem, like the spreading-out toes of a chicken foot. Such flowering heads, or inflorescences, are said to be "digitately" arranged, and other common grasses that do it include Bermuda Grass and Goose Grass. In these grasses, all the spikelets arise from one side of a flat inflorescence-branch, or rachilla. You can see a top view of one of this grass's gracefully curving, ribbon-like rachillas, with spikelets peeping out from beneath it, at http://www.backyardnature.net/n/16/160814dh.jpg

The undersides of the same rachillas, showing the spikelets, are seen at http://www.backyardnature.net/n/16/160814di.jpg

Any close look at a grass requires a glance at the ligules formed where the grass blade meets and wraps its sheath around the stem. Our path-side grass's is shown to be very different from the line of hairs seen on many grasses. Instead, it's a papery or "membranous" one, as shown at http://www.backyardnature.net/n/16/160814dj.jpg

All these features seem to me just like those of the North's Crabgrass. However, that species, Digitaria sanguinalis, isn't listed among the several Digitaria species found in the Yucatan Peninsula. Of the ones listed, ours matches DIGITARIA CILIARIS, sometimes known as Tropical Crabgrass.

The Digitaria ciliaris page of the online Manual of the Alien Plants of Belgium states that the species "... appears to be the (sub-) tropical counterpart of the more temperate D. sanguinalis. Typical plants of both are easily distinguished ... but more or less intermediate forms regularly occur and the specific boundaries, if any, remain unclear." It's surprising that Tropical Crabgrass occurs in chilly, rainy little Belgium, but it's explained that the species' seeds regularly turn up in commercial birdseed mixtures, including pheasant feed, sown there by gamekeepers.

The online Flora of China further explains why our Tropical Crabgrass might be so similar to the North's common Crabgrass with the remank that Digitaria ciliaris "...lies at the center of a complex of similar and somewhat intergrading, weedy species including D. bicornis, D. cruciata, D. henryi, D. radicosa, D. sanguinalis, and D. setigera. Occasionally intermediate specimens will be encountered that are difficult to place." Notice North America's weedy Digitaria sanguinalis in that list.

The Flora of China also tells us that about 250 crabgrass species -- members of the genus Digitaria -- are recognized worldwide. When you browse among the species you see that such neatly arranged chicken-foot flowering heads are not the rule for the whole genus. Many species distribute their rachillas along the stem, and some even array their spikelets not in racemes but in branching panicles.

Whatever the crabgrass along our trails here at the Hacienda end up being named, we can confidently say that down here in the Yucatan we have crabgrass, and it behaves and looks pretty much like the North's.

*****

TYPICAL AVOCADOS
We've already looked at avocado trees, Persea americana, but the avocado fruits we photographed then were a giant kind found in people's backyards around here, not looking much like the fruits usually found in markets. Nowadays at the Hacienda, small, more typical fruits dangle from limbs, just beginning to ripen, shown at http://www.backyardnature.net/mexnat/avocado.htm

*****

CHOCOLATE HABANEROS, & BEYOND
In the Hacienda's organic garden, rooted atop a traditional Maya kanché, the Maya gardeners Paulino and Pedro have some pepper plants growing, as shown at http://www.backyardnature.net/n/16/160814hb.jpg

At first I thought the chilies forming on them would mature into regular habaneros, but they never seemed to mature to the typical red state. Maybe they were being picked before they got red. But week after week passed and and the older chilies only managed to turn brown, as are those shown at http://www.backyardnature.net/n/16/160814hc.jpg

Finally I spoke to Paulino about it, who knows all things dealing with modern Maya life. He told me that he knew of three kinds of habaneros: red; white, and brown ones. These were the brown ones.

Looking more into the matter, on the Internet I found that Paulino's three habanero cultivars are just the beginning of a rainbow of habanero types and varieties. At the http://www.HabaneroMadness.Com website, 18 are listed, with such names as Caribbean Red, Condor's Beak, Golden and Mustard Habaneros, Scotch Bonnets, Peach and Peruvian White Habaneros, White Giants, Jamaican Chocolate, and more.

So, chocolate habaneros are growing on the kanché, but I have no idea which chocolate cultivar they are. They look liked Jamaican Hot Chocolates, which seems to be popular commercially, but that one is said to have originated in Jamaica. Though in most of Mexico the jalapeño is the main red pepper, in the Yucatan Peninsula habaneros are the overwhelming favorite. There's a good chance that what's on the kanché is an old type, maybe one that hasn't received a commercial name.

The world of chili-pepper taxonomy is rich and complex. Habaneros often are given the technical binomial Capsicum chinense, but many experts lump them into the larger species Capsicum annuum. A 2008 paper by RL Jarret and Terry Bere, appearing in HortScience 43(6) describe the genus Capsicum as embracing five cultivated species: Capsicum annuum, baccatum, frutescens, pubescens, and chinense. In Capsicum chinense, the habanero genus, the distinguishing field mark for the species is a constriction of the calyx. A side view of a flower on one of our kanché plants is shown at http://www.backyardnature.net/n/16/160814hd.jpg

I suppose that the constriction is the slightly narrowed area below the sepal bases.

On the ground next to the kanché the gardeners have sown very closely together numerous red peppers of another kind, so that the plants form a waist-high bouquet, as seen as http://www.backyardnature.net/n/16/160814hl.jpg

The plentiful peppers forming on these plants are much smaller and turn red like regular habaneros, are hot like regular habaneros, and their calyxes seem to show the same hint of a constriction observed on the kanché's chocolate habaneros, as shown at http://www.backyardnature.net/n/16/160814hm.jpg

Paulino doesn't think of these as habaneros, though. He calls them chili verde, meaning green chilies, though he clearly sees that they mature red. I don't know what to make of that. On the Internet our small peppers from plants on the ground beside the kanché look very much like those marketed as Red Dwarf Habaneros.

Often it's stated that habaneros are native to the Yucatan, but the above-mentioned 2008 HortScience paper says that the ancestral Capsicum chinense appears to have its origins in the western Amazon River basin, while the oldest known occurrence of Capsicum chinense is a 6500-year-old pod found intact in a cave in Peru. However, if habanero-type Capsicum chinense peppers were introduced into the Yucatan by the Spanish 500 years ago, there's been plenty of time for numerous cultivars to have been developed here in the Yucatan, some of them not to be found elsewhere.

Whatever the case, it's a real treat to see these old cultivars being grown here, and it's a treat to eat them along with my daily meal of beans, eggs and tortillas. Regular habaneros are so hot that I don't notice much taste to them, but the chocolate ones, to me, add a smokey flavor I associate with barbecue from back in my non-vegetarian childhood in Kentucky. The flavor doesn't register when the peppers are eaten alone, but comes out when diced and mixed with fried eggs and beans, with added oil, vinegar and lime juice.

*****

AFTERNOON STORMS
On most afternoons nowadays there's at least a little rain, sometimes a simple shower, sometimes a real gully washer. Early mornings are cloudless with sunlight glowing in treetops, but the trees are too lush and dense for slanting beams to reach the ground, where it remains dark and a little somber. During the day's first coolish hour or two you wish you could join the birds preening atop the tallest trees and snags.

By ten o'clock, already clouds are forming, usually scudding low from the east. They remind me of dirty wads of cotton blowing across recently harvested, November cotton fields back in Mississippi, fiber the cotton picker missed, ending up tangled in dead cocklebur stems at the field's edge.

Around noon, something interesting usually happens. Morning's low-scudding cloud tatters have dissipated, leaving white, evenly spaced cumulus clouds drifting calmly across blue sky. Now there's more open sky than cloud cover, so for three or four hours sunlight is very intense, the air heats up fast, and a sense of tension grows, because such scorching, glaring sunlight-energy can't just keep adding up. Something has to give.

The afternoon's first thunder starts up as early as 2 PM, sometimes as late as 6, but usually in between. Occasionally nobody shows up for my 4 PM garden walks because it's stormy, but we get lots of English folks who don't seem to notice the rain. Last Monday the rain came down so hard that when I got to the office the fellows laughed, saying that no one would show up, but that day I had three different families who hadn't met, all from England.

The day's first thunder always surprises me, because usually it's a loud boom. You wonder why you hadn't heard softer boomings leading up to it. Had the quieter ones been there, just that you hadn't noticed them, or had some atmospheric trick suppressed distant thunder to a certain point, then suddenly it gave way, letting the thunder through? Whatever the case, nowadays afternoon thunder is so natural that somehow it's comforting when that first boom does come, like an old acquaintance you may or may not get along with coming down the road every day, who'd you miss if he skipped a day.

These afternoon storms have little to do with weather fronts, and I can't see much correlation between the daily weather forecast and the rains we get. Over the whole Yucatan, afternoon air simply gets so hot that great convection currents begin stirring, hot, humid air sweeps upward, cooling, condensation takes place, and that condensation falls as rain while attendant electrical discharges spark gigantically between cloud-zones of relatively positive and negative charges. The storms form randomly like mushrooms on the forest floor, and drift overhead as part of this or that air stream, usually from east to west.

So, that's one way to look at these afternoon storms, analytically, and there's something to that approach. In fact, I enjoy weather so much that each day I check the constantly changing conditions responsible for our local weather. For example, a good general overview covering the region from the US to northern South America is provided at http://smn.cna.gob.mx/tools/DATA/MainSlider/imagen_interpretada.jpg

As hurricane season develops toward its peak in October, from time to time I check in at http://www.nhc.noaa.gov/gtwo.php?basin=atlc&fdays=2

There sometimes you can watch on a day-by-day basis low pressure systems get organized off the coast of western Africa, drift across the Atlantic as they grow into tropical storms, and maybe ultimately form hurricanes. Then you watch fascinated, wondering whether this one will hit here, or careen off somewhere else. Once a hurricane enters our region I watch its hypnotic counterclockwise motion tighten, maybe forming an eye, and when that eye forms, you know that someone is in for a lot of trouble.

The other way to enjoy storms is just to wake up each morning ignorant of what the maps show and the forecasters predict. The morning has a certain feeling, a certain smell, sound carries a certain way and the birds show a certain behavior, the sky has a certain opaqueness or clarity, and there's greater or lesser dew on vegetation than normal, and then you wait to see if what you feel turns out to mean anything.

When it's especially hot, humid and several of your natural cycles are dipping to their low points at the same time, this latter way of dealing with afternoon storms is the default one. Then, when the first thunder comes, what a luxury to crawl in under the mosquito net and listen to the booms develop, or diminish, and watch the light filtering between the wall polls soften, or harden.

If you're lucky, around 3:30 you'll awaken to cool mist drifting through the hut as silvery rivulets of rain run off the thatch, making homey splattering sounds.

There's no teaching here or deep insight to be analyzed. Just afternoon storms that are good to pay attention to.

*****

Best wishes to all Newsletter readers,

Jim

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