May 10, 2018
YUCATAN CAESALPINIA'S AMAZING GLANDS
At https://www.backyardnature.net/yucatan/caesgaum.htm we look closely at a very common, conspicuous tree in the Yucatan, the Yucatan Caesalpinia. On that page our flower close-ups show tiny, stalked glands at the base of the flowers' petals and on their stamens' filaments. Now I've noticed another kind of gland, this one quite unusual, and since Yucatan Caesalpinias aren't well documented, certain folks may be glad to hear about them.
My attention was drawn to them when, because of recent rains, most Yucatan Caesapinia trees in our area began breaking their dry-season dormancy by opening up their buds to release new stems bearing tiny leaves. The masses of immature stems and leaves as they break from their buds look like some kind of fat, deformed, hairy, yellow-green insect stuck in the axils of last season's leaves, as shown at https://www.backyardnature.net/n/18/180510cs.jpg
A close-up of the blob focusing on a doubly-compound, or "bipinnate," leaf arising from expanded bud scales is at https://www.backyardnature.net/n/18/180510ct.jpg
The glands arise at the tips of the midribs, or rachillas, of the seven main leaf divisions, or pinnae, looking like greenish golf clubs. Notice that the hooked tips of some glands bear tiny hairlike appendages, effectively increasing each gland's exposed surface area. An even closer look, better showing the glands' attachment to the rachilla tips, is at https://www.backyardnature.net/n/18/180510cu.jpg
Often we've seen glands that apparently were providing something desirable such as nectar to ants and other invertebrates, but my impression is that these glands are to ward off visitors who might nibble on the leaves' soft tissue.
While watching a tree with numerous expanding buds, several times I saw ants climbing the stems and exploring among the older leaves as well as these emerging ones, apparently looking for prey. Several times ants embarked into the enlarging mass of stems and leaves, started to climb one of the gland-bearing pinnae, but each time turned around before reaching the tip. My impression was that they left the area faster than they'd come. One ant climbing a pinna simply fell off onto the ground. Was he clumsy, or did he encounter some kind of chemical in the air surrounding the pinna-tip gland that shocked him so violently he simply wanted to escape from the area as quickly as possible?
A few days after the above photos were taken, and the new leaves were nearly as large as last year's, at the tips of most pinnae the stalked glands were missing, but on some, brown, shriveled, dried-up stalks still could be seen. However, now most new leaves and stems on most trees were heavily infested with an especially tiny aphid, so the glands didn't prevent that.
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WHITESEED MANGA'S YELLOWING FLOWER HEADS
At https://www.backyardnature.net/yucatan/manganse.htm we look at an acacia-like tree, the Whiteseed Manga, one of which roots on the opposite side of the deep pit extending to beneath the hut's porch. It reaches for sunlight with branches that cross the pit and almost touch the hut's thatch roof. Therefore, it was hard to miss the fact that this week the tree reached its peak in flowering. You can see a skipper taking nectar from one of its hundreds of flower clusters at https://www.backyardnature.net/n/18/180510cn.jpg
In that picture notice that certain of the clusters are white -- the whiteness contributed by stamen filaments radiating from individual flowers in the cluster -- while others are yellowish. The yellowness appears when white stamen filaments wilt and turn yellow. The white clusters remain white only during the morning of the first day the cluster opens; in afternoons and for several subsequent days, until the flowers fall away, the clusters are yellow. A close-up showing a white flower cluster with fresh stamen filaments beside a yellow one with drooping filaments, is at https://www.backyardnature.net/n/18/180510co.jpg
In both of the above pictures, skippers are taking nectar from white clusters, not the older yellow ones. Having watched the flowers for several hours, I've not seen a single butterfly or bee land on a yellowed cluster.
This is the tree's way of signaling to its pollinators that their time would be better spent visiting younger flowers, which are white. I've read that to insect eyes yellow flowers are much less visible than white ones, so it all makes sense.
I read that Whiteseed Mangas are highly regarded by beekeepers for their nectar production. That information is hard to reconcile with my having seen much fewer pollinators visiting flower clusters on several trees than seemed normal. For ten minutes during one recent morning just when I thought pollinators would be busiest, I stood beside a Whiteseed Manga in the clearing below the hut, and saw not a single butterfly or bee, not even a small, native bee, visiting any cluster.
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CYDISTA TRUMPET VINE'S WHITE FLOWERS
At https://www.backyardnature.net/chiapas/cydista.htm we look at a prettily flowering woody vine, or liana, met with in Chiapas, in 2016. On that page you'll see that the handsome blossoms are mostly pale yellow. This week the same species has been flowering here, but our vines produce mostly white flowers, as shown at https://www.backyardnature.net/n/18/180510cy.jpg
A closer look at the flower from the side is at https://www.backyardnature.net/n/18/180510cz.jpg
These white flowers are in line with information in the literature, which reports white- and yellow-flowered forms of Cydista potosina. The stems of our white-flowered vines are much more strongly squared in cross section, with sharp, almost winged corners, than those seen on the yellow-flowered Chiapas plants, but that may be caused by differences in climate, vine age, and other factors. You can see our Yucatan vine's strongly angled stem at https://www.backyardnature.net/n/18/180510cx.jpg
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GIANT BARREL CACTUS
During my recent camping trip in the highlands east of Saltillo, 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), where trees were just starting to appear, I found the handsome barrel cactus shown at https://www.backyardnature.net/n/18/180510ec.jpg
Among features important for identification purposes we can see that this is a large, ±spherical cactus, with spines arising in clusters from atop conspicuous vertical ridges pleating the cactus's body. Clusters of spines are shown close up at https://www.backyardnature.net/n/18/180510ed.jpg
Notice that the clusters arise from spots known as areoles. In the picture, five spines arise from each areole. The fifth spine may escape you at first, for it's smaller and much slenderer than the others; it arises at the base of the largest, thickest spine, and points upward.
This cactus belongs to a large group commonly known as barrel cacti, and several barrel cactus species display features more or like these. The field mark on the one in the photo distinguishing it from most other species is that large tuft of golden-white items at the cactus's very top, a close-up shown at https://www.backyardnature.net/n/18/180510ee.jpg
You can guess that those are old flowers, the corollas drying up and turning brown as the ovaries beneath them swell into fruits. I'd assumed that such flowering/fruiting remnants would remain on the cactus body for only a brief time during its yearly life cycle, which is what I've experienced with most other cactus species. However, on the Internet and in books, most images I find of the species show such tufts, so they must be long enduring and and somewhat distinctive for the species.
Happily 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 fine work I learn that our cactus is ECHINOCACTUS PLATYACANTHUS. In English it's known as the Giant Barrel Cactus, though other species may share that name. Echinocactus platyacanthus is endemic to the Chihuahuan Desert part of central Mexico, where often it occurs in abundance. It can grow up to seven feet tall (2m), and individuals over 400 years old have been encountered.
This cactus is much appreciated for its size and ornamental qualities, for which reason it's suffered from collectors. Even more threatening to its numbers are forest fines and livestock grazing. In Mexico the species is considered as vulnerable.
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FIRE BARREL CACTUS
It's embarrassing to admit that I didn't realize I had a second species of big cactus when I encountered in the same general area as the Giant Barrel Cactus the one shown at https://www.backyardnature.net/n/18/180510ff.jpg
I assumed that the reddish spines atop this cactus were what I'd see atop a Giant Barrel Cactus when it wasn't flowering or fruiting. In the above picture, my sunhat is 16½ inches across (40cm). The cactus is about 2.2 hats high, so it's a little over three feet tall (88cm). It wasn't until I was back in the Yucatan with the above picture on my laptop that I enlarged a view of the cactus's top and realized we had a second species. The evidence is shown at https://www.backyardnature.net/n/18/180510fg.jpg
Those white, hairlike items issuing from spine cluster bases aren't present on Giant Barrel Cactuses. Also, the spines themselves are a little different. In the end, it was those reddish spines at the cactus's top that enabled me to identify it in Alfredo Flores's Guía de Cactáceas del Estado de Coahuila as FEROCACTUS STAINESII ssp PILOSUS.
Being such an impressive species, it's known by several English names, including Mexican Lime Cactus, Mexican Fire Barrel Cactus, and just plain Fire Barrel. It's endemic just to the semi-desert, usually limestone mountains of northeastern and north-central Mexico, usually between 1600 and 2000 meters in elevation. Being so handsome, it suffers greatly from collectors, plus it suffers from local people who eat the flower buds. Habitat destruction by agriculture and ranching is its main problem, however. Fire Barrel Cactus can grow up to 10ft tall (3m).
Two Fire Barrel subspecies are recognized, our pilosus with wispy, white, wiry items around the spine base, and subspecies pringlei without the white, wiry items.
You can see where the Fire Barrel Cactus got its name in a picture taken when early morning sunlight backlighted its mantle of red spines, on a mountain slope right where semi-desert bushland started transistioning to scrubby forest, at https://www.backyardnature.net/n/18/180510fh.jpg
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WHAT IS "NATURE"?
A visitor to the hut told me I was lucky to "live in Nature." At that point I knew I've made a philosophical journey, because at first the remark seemed so silly.
For, I remember as a child on the farm in Kentucky when there was no talk of Nature at all. It wasn't a concept ever mentioned. It wasn't until the late 50s or so when we got TV that I understood from Walt Disney that Nature was pretty flowers, birds and butterflies, and Bambi.
When I began taking biology classes in college and saw a need to refine my definition, I decided that "Nature" was the forest, oceans, deserts and the like, but it ceased to exist when humans changed it in any way. Subterranean coal strata were part of Nature, but when the coal was dug out it became something unnatural, a product of human industry.
Now at age 70 it's perfectly clear to me that "Nature" is everything. That's why the hut visitor's remark confused me: Of course I live in Nature, like everyone else.
Maybe the biggest advantage of thinking like this is that when it's obvious that humans and our workings are natural, it's easier to accept that we, too, are subject to natural laws -- laws such as the ecological one that a community or individual can't endure unchanged for long while consuming more resources than the environment can provide. Just imagine how many of humanity's problems would not exist -- a big potential advantage -- if we'd all been respecting that law from the beginning.
The belief that everything is natural does not suggest that the Universe is like a big machine, and that the behavior of us natural things is mechanistic. For, there must be some kind of creative impulse that has sparked everything -- matter, life, mentality, feelings -- into existence, and keeps it evolving toward higher, ever more sophisticated states.
Nearly everything we humans see, think and do is indeed mechanistic, but those sparks of creation that brought the Universe into being, and the impulses directing the created things' evolution to ever higher levels, are sovereign urgencies doing new things right now. When we humans make a conscious effort to harmonize our thinking and behavior with that voluptuous process -- often refusing to honor thoughts and behaviors urged by our genetic programming -- we are exercising free will to participate in the creative evolutionary process. When we succumb to our genetic programming, we remain as machines.
At this point it's possible to notice something pretty: That is, it's as if Spinoza's "Nature = God" is an equation in which various forms of evolution are shifting things from the left to the right: Nature --> God.
This further sets the stage, at least for me, for thinking that maybe the notion that "All is One" is apt. It's just that the "One Thing" mysteriously has occupied Herself with dreams manifesting as us things of Nature. Gradually, as universal evolution shifts things to the right, The One Thing awakens.
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Best wishes to all Newsletter readers,
Jim
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