Brugmansia comprises seven species — B. arborea, B. aurea, B. insignis, B. sanguinea, B. suaveolens, B. versicolor, and B. vulcanicola. Brugmansia are native to tropical regions of South America, along the Andes from Venezuela to northern Chile, and also in south-eastern Brazil. No wild plants have ever been confirmed, and all seven species are listed as Extinct in the Wild by the IUCN Red List. Human cultivation has ensured the genus' continued survival.
The Plants
Brugmansia are large shrubs or small trees, with semi-woody, often many-branched trunks. They can reach heights of 3-11 m (10-36 ft). The name "angel's trumpet" refers to the large, pendulous, trumpet-shaped flowers, 14-50 cm (6-20 in) long and 10-35 cm (4-14 in) across at the opening. They come in shades of white, yellow, pink, orange, green, or red. Most Brugmansia are fragrant in the evenings to attract pollinating moths. The sword-billed hummingbird is the exclusive pollinator of Brugmansia sanguinea.
The seven species are divided into two natural, genetically isolated groups. The warm-growing group is the section Brugmansia, and the cold group is the section Sphaerocarpum. Brugmansia are grown as ornamental container plants worldwide, and have become naturalized in isolated tropical areas around the globe.
A young seedling grows straight up, usually on a single stalk, until it reaches its first main fork at 80-150 cm high. It flowers only after reaching this fork, and then only on new growth above the fork. Both woody and leafy tip cuttings are used to propagate Brugmansia.
Scent Chemistry
The floral essential oil of Brugmansia suaveolens changes dramatically between the freshly opened night blossoms and the rose-colored senescent blossoms of the following day. The white blossoms were dominated by 1,8-cineole (72.1%), (E)-nerolidol (11.7%), α-terpineol (5.3%), and phenethyl alcohol (3.2%). In the rose-colored blossoms, 1,8-cineole falls to 2.0% and (E)-nerolidol to 1.9%, while megastigmatrienones rise to 35.5%, nonanal to 17.4%, terpinen-4-ol to 10.5% and heptanal to 10.2%, and phenethyl alcohol is no longer detected.
Headspace sampling of Brugmansia × candida showed floral volatiles rich in (E)-β-ocimene (38-52%) and 1,8-cineole (5-19%), with smaller amounts of phenethyl alcohol (1-3%) and (E)-nerolidol (5-6%). A headspace analysis of Brugmansia suaveolens reported a sample dominated by benzenoids, predominantly methyl benzoate (18.7%), as well as 1,8-cineole (25.5%) and geraniol (17.9%). Geraniol, methyl benzoate, and nerolidol floral emissions of B. suaveolens peaked between midnight and 4:00 am.
The theaspiranes and megastigmatrienones are C13 nor-isoprenoids derived from carotenoids, and are notable components of tobacco and other members of the Solanaceae. In Brugmansia suaveolens, 50 volatile compounds have been identified in the flowers and leaves, most of them in the flowers.
Brugmansia suaveolens
Brugmansia suaveolens, called Brazil's white angel trumpet, is a species of the nightshade family native to south-eastern Brazil. It was originally endemic to the coastal rainforests there, where it grows below 1,000 m along river banks and forest edges. It is a semi-woody shrub or small tree, growing up to 3-5 m tall, with oval leaves up to 25 cm long. The large pendulous flowers are pale yellow before opening, open at night to white flaring corollas, and turn a rose color the following day. They are about 24-32 cm long. The Latin epithet suaveolens means "with a sweet fragrance". The flowers hang half-closed during the day and return to their peak in the evening.
There are thousands of cultivated Brugmansia hybrids, and the majority have at least some B. suaveolens heritage. As a result of human interaction, the species can now be found growing in residential areas throughout much of South America, and occasionally in Central America, Mexico, California, Greece, Africa and parts of Florida.
Chemically, B. suaveolens is well studied: 59 alkaloids have been identified in its mature and immature flowers, fruits, corolla, roots and flower nectar.
Toxicity
All parts of Brugmansia are potentially poisonous, with the seeds and leaves being especially dangerous. The toxic effect is attributed mainly to the tropane alkaloids atropine and scopolamine (hyoscine), and hyoscyamine is also present. These alkaloids can lead to anticholinergic toxidrome and delirium. Effects of ingestion can include confusion, tachycardia, dry mouth, constipation, tremors, delusions, mydriasis, and death.
Alkaloid concentrations differ markedly in all parts of the plant and vary with the seasons and the level of hydration, so it is nearly impossible to determine a safe level of alkaloid exposure. In the flowers of B. suaveolens, atropine and scopolamine average 0.79 and 0.72 mg per gram of dry plant, and the flower nectar also contains scopolamine. A woman who rubbed her right eye after touching the leaves and flowers of Brugmansia suaveolens presented with a dilated right pupil.
