Brugmansia

Taxonomy

Linnaeus first classified these plants as part of Datura with his 1753 description of "Datura arborea". Then in 1805, C. H. Persoon transferred them into a separate genus, Brugmansia, named for Dutch naturalist Sebald Justinus Brugmans. For another 168 years, various authors placed them back and forth between the genera of Brugmansia and Datura, until in 1973, with his detailed comparison of morphological differences, T.E. Lockwood settled them as separate genera, where they have stayed unchallenged since. The genus Brugmansia is placed in the tribe Datureae.

Species

Currently, there are seven recognized species:

These species are then divided into two natural, genetically isolated groups. The section Brugmansia sect. Brugmansia (the warm-growing group) includes the species B. aurea, B. insignis, B. sauveolens, and B. versicolor. The section Brugmansia sect. Sphaerocarpum (the cold group) includes the species B. arborea, B. sanguinea, and B. vulcanicola.

Two of these species were challenged by Lockwood in his 1973 doctoral thesis. First, Brugmansia vulcanicola was said to be a subspecies of B. sanguinea, but this was refuted by Lockwood's former mentor, R. E. Schultes in 1977. Second, Lockwood proposed that the species B. insignis was instead a hybrid of the combination (B. suaveolens × B. versicolor)× B. suaveolens. This was later disproved by crossbreeding experiments done by the Preissels, published in 1997.

Distribution and habitat

Brugmansia are native to tropical regions of South America, along the Andes from Venezuela to northern Chile, and also in south-eastern Brazil. They are grown as ornamental container plants worldwide, and have become naturalized in isolated tropical areas around the globe, including within North America, Africa, Australia, Asia, and Europe.

Ecology

Most Brugmansia are fragrant in the evenings to attract pollinating moths. One species lacking scent, the red-flowered Brugmansia sanguinea, is exclusively pollinated by the sword-billed hummingbird. Brugmansia have two main stages to their life cycle. In the initial vegetative stage the young seedling grows straight up, usually on a single stalk, until it reaches its first main fork at 80–150 cm (2.6–4.9 ft) high. It will not flower until after it has reached this fork, and then only on new growth above the fork. Cuttings taken from the lower vegetative region must also grow to a similar height before flowering, but cuttings from the upper flowering region will often flower at a very low height.

One example of plant/animal interaction involves the butterfly Placidula euryanassa, which uses Brugmansia suaveolens as one of its main larval foods. It has been shown that these can sequester the plant's tropane alkaloids and store them through the pupal stage on to the adult butterfly, where they are then used as a defense mechanism, making themselves less palatable to vertebrate predators.

Brugmansia seed dispersal was probably formerly accomplished by mammalian megafauna, extinct since the Pleistocene. Brugmansia has long been extinct in the wild as their fruits now shrivel on the plants without progeny. They have been maintained in cultivation as a source of psychotropic drugs, as well as for ornamental purposes, following the loss of their evolutionary seed dispersal partner by humans.

Historical uses

Brugmansia are most often grown today as flowering ornamental plants.

Brugmansia contains deliriant hallucinogenic tropane alkaloids (atropine, scopolamine, and hyoscyamine), which cause delirium and hallucinations. In modern medicine, these tropane alkaloids found in Brugmansia and other related members of Solanaceae have proven medical value for their spasmolytic, anti-asthmatic, anticholinergic, narcotic, and anesthetic properties, although many of these alkaloids, or their equivalents, are now artificially synthesized.

Brugmansia species have also traditionally been used in many South American indigenous cultures in medical preparations and as an entheogen in religious and spiritual ceremonies. Medicinally, they have mostly been used externally as part of a poultice, tincture, ointment, or where the leaves are directly applied transdermally to the skin. Traditional external uses have included the treating of aches and pains, dermatitis, orchitis, arthritis, rheumatism, headaches, infections, and as an anti-inflammatory. They have been used internally much more rarely due to the inherent dangers of ingestion. Internal uses, in highly diluted preparations, and often as a portion of a larger mix, have included treatments for stomach and muscle ailments, as a decongestant, to induce vomiting, to expel worms and parasites, and as a sedative.

Several South American cultures have used Brugmansia species as a treatment for unruly children, so that they might be admonished directly by their ancestors in the spirit world, and thereby become more compliant. Mixed with maize beer and tobacco leaves, it has been used to drug wives and slaves before they were buried alive with their dead lord.

In the Northern Peruvian Andes, shamans (curanderos) traditionally used Brugmansia species for initiation, divination, and black magic rituals. In some Latin American countries such as Colombia and Peru, members of the genus Brugmansia are reportedly used by malevolent sorcerers or "bad shamans" in some ayahuasca brews in attempt to take advantage of tourists. The species that are typically used for these purposes include Brugmansia suaveolens and Brugmansia arborea among others.

Toxicity

All parts of Brugmansia are potentially poisonous, with the seeds and leaves being especially dangerous. Brugmansia are rich in scopolamine (hyoscine), hyoscyamine, and several other tropane alkaloids that can lead to anticholinergic toxidrome and delirium. Effects of ingestion can include paralysis of smooth muscles, confusion, tachycardia, dry mouth, constipation, tremors, migraine headaches, poor coordination, delusions, visual and auditory hallucinations, mydriasis, rapid onset cycloplegia, and death.

The hallucinogenic effects of Brugmansia were described in the journal Pathology as "terrifying rather than pleasurable". The author Christina Pratt, in An Encyclopedia of Shamanism, says that "Brugmansia induces a powerful trance with violent and unpleasant effects, sickening after effects, and at times temporary insanity". These hallucinations are often characterized by complete loss of awareness that one is hallucinating, disconnection from reality (psychosis), and amnesia of the episode, such as one example reported in European Archives of Psychiatry and Clinical Neuroscience of a young man who amputated his own penis and tongue after drinking only one cup of Brugmansia sanguinea tea.

In 1994 in Florida, 112 people were admitted to hospitals after ingesting Brugmansia, leading one municipality to prohibit the purchase, sale, or cultivation of Brugmansia plants. The concentrations of alkaloids in all parts of the plant differ markedly. They even vary with the seasons and the level of hydration, so it is nearly impossible to determine a safe level of alkaloid exposure.

In 2022 The BMJ reported the following case: A woman in her 50s presented to the emergency department with blurred vision and pupil asymmetry for 3 hours. The right pupil was dilated, while the left was normal. A detailed history revealed that she had been pruning plants in her garden, when the blurred vision started. She did not complain of any other symptom. When all tests proved normal, she was finally asked to provide a photo of her garden. Brugmansia suaveolens (angel's trumpet) was identified in the picture. On asking specific history, she reported rubbing her right eye after touching the plant's leaves and flowers. Anecdotally, this case demonstrates the tendency for active compounds in Brugmansia plants to easily be transferred to the hands when handling the plant.

Cultivation

Brugmansia are easily grown in a moist, fertile, well-drained soil, in sun to part shade, in frost-free climates. They begin to flower in mid to late spring in warm climates and continue into the fall (autumn), often continuing as late as early winter in warm conditions. In cool winters, outdoor plants need protection from frost, but the roots are hardier, and may resprout in late spring. The species from the higher elevations, in B.section Sphaerocarpium, prefer moderate temperatures and cool nights, and may not flower if temperatures are very hot. Most Brugmansia may be propagated easily by rooting 10–20 cm (4–8 in) cuttings taken from the end of a branch during the summer. Several hybrids and numerous cultivars have been developed for use as ornamental plants. B. × candida is a hybrid between B. aurea and B. versicolor; B. × flava is a hybrid between B. arborea and B. sanguinea; and B. × cubensis is a hybrid between B. suaveolens, B. versicolor, and B. aurea. There are cultivars producing double flowers, and some with variegated leaves. The cultivars B. × candida 'Grand Marnier' and 'Knightii' have gained the Royal Horticultural Society's Award of Garden Merit.