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Excerpts from Jim Conrad's
Naturalist Newsletter
entry from field notes dated July 2, 2022, taken on Cerro de la Cruz, at an elevation of ~2885m (~9465 ft), just south of the community of El Pinar, Amealco de Bonfil, Querétaro, MÉXICO, (~N20.17°, ~W100.17°)
TEPOZÁN
On Cerro de la Cruz's lower eastern slope the locals over the years had haphazardly cleared away most of the trees but here and there amid the resulting scrub and grass -- still droughty gray and brown after a long dry season and a very late rainy season -- small trees still occurred, such as the one shown above. Most of its leaves had fallen off, probably as a water-saving adaptation. Up close the branches looked healthy, issuing new leaves despite the lack of rain:
The heavy coating of white hairs on young stems and leaf undersides was another water-saving adaptation. Wrinkled, or "rugose," leaf surfaces such as seen above have been suggested as an adaptation to cold temperatures by Han Wang and others in their 2022 study "Leaf morphological traits as adaptations to multiple climate gradients." A thick coat of hairs to cut down on water loss and wrinkles for the chill: That's about right for a lone tree on this high-elevation, wind-swept field.
The hairiness was spectacular. Hairs displaying this kind of curdled-milk woolliness are said to be "floccose" when they exhibit tufts of soft, woolly hairs which tend to rub off. Young leaves were less hairy on top, and older ones hardly hairy at all on top, plus older woody branches weren't floccose at all. So many variables influence a species' evolution that particular features seldom can be explained by any specific need, but in general it can be said that white hairs reflect solar radiation, and dense hairs cut down on water evaporation and damage from temperature extremes. Whatever the case, this tree seems to find satisfaction in heavily coating its youngest parts with flocculose white hairs.
Several plant families are capable of producing trees with such white floccosity, so it was fortunate that a few of this tree's limbs bore the panicle-type inflorescences seen above. In that picture, the yellow item looking like an empty milkweed pod husk must be a dried-up leaf. Also in the picture it's seen that branch tips can be squared in cross section. And notice on the stem at the far right how the white hairs are being worn off the older part. These are all good hints for the plant family our tree belongs to but, seeing them, I still wasn't sure which.
The inflorescence's tiny parts weren't little fruits, as I'd anticipated, but rather dried-up flowers, as seen at the far left in the above picture, where a black, puckered corolla emerges from a black, hairy calyx. Later I realized that our plant was dioecious -- having male flowers on one tree, female on the other -- so possibly these are spent male flowers. However, usually male flowers, once they've dispersed their pollen, simply fall off. Another possibility is that the tree, anticipating the rainy season's normal arrival in May, flowered on schedule, but when the rains didn't develop the tree aborted the flowers, saving water.
The flower's size and shape provided the identification break-through, for we've seen a similar combination of such small flowers in panicles on woody plants white with a coating of dense hairs. It was the Escobilla Butterflybush, occurring in lower, more arid central Querétaro. Butterflybushes, the genus Buddleja, nowadays usually are placed in the Snapdragon/Figwort Family, the Scrophulariaceae. With this insight our tree's identity was easy to figure out.
It's BUDDLEJA CORDATA, distributed throughout most of upland Mexico, into Guatemala. It occurs in a wide variety of environments, from highland fir, pine and oak forests, to disturbed sites of many kinds, including abandoned fields and even weedy parts of towns, and over a large elevation range, from 1000-3200 meters (3300-10,500 ft). In rainier areas it can grow 25 meters high (82ft). It bears no English name, but in Spanish our tree and similar species commonly are called Tepozán.
The Flora del Bajío describes our tree as a bush or a tree, and indicates that as a bush can remain as short as 1.5m (5 ft). Three subspecies have been recognized for the species; ours is the typical one, the only one found in this area, subspecies ordata. In genera, this is a very variable plant.
The Atlas de las Plantas de la Medicina Tradicional Mexicana Tepozán page tells us that branches of our tree, often along with other plants, traditionally have been boiled in water for washing mothers who have just given birth, to prevent them from getting chilled and having a cold. This sounds like the Doctrine of Signatures -- that herbs "sign" or signal to us humans how they should be used for cures. In this case, the woolly covering of the tree's younger parts might be the sign.
Beyond that, the leaves can be boiled and applied as a poultice to wounds, sores and bruises, plus the leaves can be toasted and crushed with pork fat to make a healing ointment. Other recipes are provided for stomach aches, children with diarrhea, general infections, kidney problems, headaches, snake bite, rheumatism, cough, diabetes, nosebleed, cancer, dish-washing disinfectant, cramps, and more.
In fact, numerous studies find that several Buddleja species, including Tepazón, contain the glycoside called verbascoside, known to be effective against various inflammations and to kill Staphylococcus aureus bacteria, which can cause various kinds of infections and food poisoning. The 2021 study by Gladys Chirino-Galindo and others entitled "Verbasoside-enriched fraction from Buddleja cordata Kunth ameliorates the effects of diabetic embryopathy in an animal model" found that Buddleja cordata extract "...reduces the frequency and severity of fetal malformations produced by chemically induced diabetes, and additionally partially ameliorates the diabetic condition."
Entry dated November 9, 2023, from notes taken near Cascadas de La Piedad waterfall 3kms NW of the community of San Pablo, municipality of Almeaco de Bonfil; beside canyon of La Piedad; N20.1017°, W100.0041°, elevation 2360 meters (7750ft); extreme southern Querétaro state, MÉXICO
FLOWERING, SHRUBBY TEPOZÁN
Just below the rim of the canyon, the above flowering woody bush glowed in a narrow beam of intense morning sunlight. It certainly didn't look like the isolated, gnarly, late-season tree documented in the preceding entry. The large, much-branched, panicle-type inflorescences were distinctive, the leaves were simple, and the lower stems were woody.
Inflorescence branches where white-woolly, but the woolliness quickly diminished below the inflorescence's base.
The 2003 treatment of Buddleja species in the Flora del Bajío describes our Buddlea cordata as dioecious -- male flowers and female flowers appearing on different plants, so that individuals are either male or female. Above, the flower at the picture's top, left bears five stamens with yellow anthers, but no sign of an ovary is seen, so our plant is male. Here's a closer look at one of our plant's leaves:
At the picture's top, left it's seen that leaves arise in pairs along the stems.
Undoubtedly, Buddleja cordata displays flexible habitat requirements, and its growth form and general appearance varies according to its environment. This adaptability hasn't gone unnoticed by Mexican campesinos, people working on the land. The 2021 study by Gonzalo Halffter Salas and his team entitled "Evaluar la Salud Ambiental en Zonas Ganaderas de Veracruz y Chiapas Utilizando como Indicadores a los Escarabajos Estercoleros," noted that in Mexico's Veracruz state thirteen woody plants provided livestock forage while serving as "living fences," cercas vivas, in "agrosilvopastoral systems." Agrosilvopastoral systems comprise a subset of the agroforestry concept. The study found Buddleia cordata serving as one of those species.