PLANTS | ANIMALS | ECOLOGY | FUNGI | GEOLOGY | GARDENING | TOOLS
MEXICAN PLANTS & ANIMALS HOME
Excerpts from Jim Conrad's
Naturalist Newsletter
entry dated May 18, 2022, notes from a camping trip among hills within two kms of La Higuera, about 7kms ENE of Tequisquiapan, Querétaro state, MÉXICO
elevation about 2020m (6600 ft), near N20.57°, W99.85°
TORCHWOOD COPAL FLOWERING & FRUITING
On rocky, grassy slopes around La Higuera, a certain late-dry-season-leafless, somewhat picturesquely scraggly bush or small tree clawed at me as I backpacked through the scrub. A stiff twig got caught in a backpack strap and as I reached to free it I noticed a little, white blossom, only about 10mm across (0.3 inch), about the size of the nail on a small finger, shown above. In the landscape's parched, gray-brown condition, such a fragile looking little being was a pleasure to behold.
The vast majority of blossoms in the world of flowering trees and bushes have their parts in 4s, 5s or multiples thereof, the main exceptions being monocot trees such as the palms. Their flower parts occur in multiples of 3s. This blossom produces three petals, but it's obviously no palm. The main non-palm plant family capable of flower parts in 3s is the Euphorbia Family, so at first glance I figured that this was a "euphorb." The Euphorbia Family is a big one, especially in the tropics, so I knew to notice all the details I could, for later identification.
Some flowers had already been pollinated, the corolla ejected, and the ovaries had begun enlarging into immature fruits at various stages, as shown below:
An important field mark to notice in the above picture is that at the outermost tip of the largest immature fruit, in the picture's upper-right corner, you can barely make out three "sutures" radiating down the length of the future fruit, so it's clear that the ovary contained three compartments, or carpels, which is normal for the Euphorbia Family. Also, here and there on other parts of herbage emerging from the long-dormant bud are tiny, dark, shiny wart-like things, which are glands, probably exuding chemicals that attract pollinators, or repel herbage-eating insects, also OK for the Euphorbia Family. The small tree or bush bore a single, almost mature fruit, shown below:
It's like a tiny grape, including being covered by a frosty bloom, or "glaucescence," which helps protect the fruit from our late dry-season intense sunlight.
And then I noticed that from some buds leaves were just beginning to unfold:
This pinnately compound leaf is all wrong for the Euphorbia Family, whose vast majority of species produce simple leaves not divided into leaflets, as this one is. A few euphorb species produce compound leaves, but with leaflets all radiating from one spot atop the leaf stem, or petiole, as with clover leaves. This was confusing until I noticed the little tree's somewhat swollen trunk:
Not only was the trunk swollen, but when I looked around there was another tree like this one, but older, with an even more bloated trunk, plus the trunk's thin outer bark was peeling offing exactly like a species that during my years in the Yucatan and Chiapas was an everyday presence, and much noticed by the tourists I worked with, not only because of its unusual looking trunk but for the stories behind it -- the famous Gumbo Limbo, Bursera simaruba. Here's the older tree's trunk:
It turns out that about a hundred species of the genus Bursera are recognized, all native to the Americas, with the genus's center of diversity being the Mexican Pacific slope. About ten species occur in our general area, the Bajío, and Gumbo Limbo is one of them. The genus Bursera belongs to what's often called the Torchwood Family; it's the Burseraceae. The name Torchwood comes about because the wood produced in this family is very resinous and readily burns, like pine, and splinters of it can be burned torch-like. The resin and smoke from burning the dried resin smells good, so the dried resin often is burned as incense, and the fresh resin often is used medicinally. Frankincense and myrrh are dried resin from members of this family, and the copal burned as incense during ceremonies of indigenous Americans, particularly the Maya, is dried resin from various members of this family, including some Bursera species.
Our flowering tree often is known by the English name of Torchwood Copal, as well as Fragrant Bursera; it's BURSERA FAGAROIDES, distributed from arid southern Arizona (at least earlier, for it may have been extirpated) south in the arid Mexican uplands to about Mexico City. Earlier it was regarded as commonly occurring but now sometimes is hard to find, and in many areas it's disappeared completely, supposedly because people like to burn its fragrant wood. I read that, as with Gumbo Limbo, you can stick an unrooted stem of this species into the ground, it'll root to form a living fencepost, and eventually you can have a fence attached to a line of trees. I've not seen that in this arid zone, however.
Knowing that this tree was a Bursera, a certain feature of our little three-cornered flower was realized: Nearly always flowers in the Torchwood Family, the Burseraceae, are unisexual with trees being either male or female. Our flower on a fruit-producing and therefore female tree displays both a functioning ovary, the female part, plus obvious stamens, which are pollen-producing male parts. So, do we have one of the those very unusual in-between flowers? On the Internet it's seen that on male trees the flowers' stamens are much more prominent than on our flower, and the ovary much reduced. Apparently the smaller stamens on our tree's flower are vestigial and sterile.