This is the only geopolitical region which extends from the Arctic circle to the Antarctic circle. This, in combination with other geographic factors, results in an impressive biological diversity — more than 100,000 species of higher plants occur naturally on these continents. At the same time it is or was the home to numerous indigenous groups speaking a multitude of languages. It is estimated that about 1,200 ethnolinguistic groups existed in 1492, but today about 420 (i.e., only a third) remain. Most of these belong to the poorest sections of society in their respective countries. Recent attempts to strengthen indigenous traditions have been diverse and it is to be hoped that these attempts succeed in improving the generally appalling living conditions and strengthening the local traditions. The Amazon basin and the Central American region are particularly diverse botanically. Historically, some regions of the Americas have distinguished themselves for the development of dominant cultures that left impressive religious and civil monuments, like the Maya, Zapotecs/ Mixtecs, and Aztecs (Nahua) in Mesoamerica, and the Inca in South America. In the case of the Aztecs, some written manuscripts or codices are available which record the use of plants for food, medicine, and many other purposes. The most important and oldest source is a herbal written in Nahuatl by Martin de la Cruz and translated into Latin by Juan Badiano. It was given to the King of Spain, Carlos V, in 1552. It was written rather hastily and has numerous color illustrations of medicinal plants. There have been several attempts to identify plants from this herbal and most of the identifications seem to be botanically sound. The major problem with this source is the European influence that being felt only 30 years after the conquest of Mexico-Tenochtitlan. Also the Nahuatl author attempted to show “European sophistication.”
Another important source is Fray Bernadino de Sahagun’s work. It is certainly the best source available for the early historical period. This Franciscan missionary arrived in Mexico in 1529 and worked there until his death in 1590. The methods he used compare favorably with modern ethnographic techniques. He posed questions in Nahuatl to a group of ten to twelve elderly informants, and their answers were recorded in Nahuatl by trilingual (Nahuatl, Latin, Spanish) student scribes. The questions were then developed into a more extensive questionnaire used in communities around Mexico-Tenochtitlan. He left several codices (among them the Codex Florentino, compiled ca. 1570) and on the basis of these documents he wrote the Historia General de las Cosas de Nueva Espana (published 1793). From an ethnobotanical point of view, the source is somewhat more difficult to use than the Codex Cruz/Badianus because there are fewer botanical identifications and these are less certain. The strength lies more than anything in its description and analysis of medicinal concepts.
Let us now turn to North America. Most of our knowledge about medicinal plant traditions on the continent is due to anthropological and ethnobiological research conducted mostly since the second half of the 19th century. An excellent summary of these data is provided by Moerman (1998), who summarizes fieldwork by ethnographers who recorded such oral traditions in the late 19th and early 20th centuries.
Guava Psidium guajava / Myrtaceae
A brief mention has to be made of guyava or guava, a Mesoamerican tree which is now pantropi-cally cultivated especially for its fruit. As is the case with many food plants, it is also used medicinally. The leaves and bark are commonly used in the treatment of diarrhea and some other gastrointestinal disorders. While it is not used biomedically, it is used in popular medicine and dates back to at least the Aztecs of the 16th century.
Passionflower Passiflora incarnata / Passifloraceae
In the days following their conquest of South America, the Europeans became interested in the passion flower. Its unique and very conspicuous flower reminded the conquistadors of the Passion of Christ, and they saw all the symbols of his suffering in the flower: the crown of thorns in the corona, the five wounds in the five anthers, the nails of crucification in the three stigma, the ten apostles (less Peter and Judas) in the five plus five lobes of the calyx and corolla, and the hands and whips of Christ’s persecutors in the tendrils and lobed leaves. The aerial parts (Passiflora herba) are today used in the treatment of nervousness and unrest.
Quinine tree Cinchona spp. / Rubiaceae
Cinchona, the quinine tree, raises a series of fascinating questions about indigenous plant use and drug development. It is uncertain whether species of this genus were used pharmaceutically by the native populations of tropical South America prior to or during the 17th century. According to Schneider and Tschirsch (1910), the bark of this species was not used medically to a great extent, and it was known to specialists as a remedy in the treatment of “fever” (malaria) only in a very limited region. Since it is still doubtful whether malaria was endemic to the Americas prior to the conquest by the Europeans, it would seem unlikely that the bark would have been of any relevance. The bark and its use was popularized by the Jesuits (“Jesuits’ powder”), and since 1687 it has been recorded in several lists of medicines (first in the “Arzneitaxe” of Frankfurt-on-the-Main, Germany). Its use as a remedy for malaria, and also for other forms of fever, spread very rapidly across Europe. In the mid-19th century the tree was introduced to Java and is now grown in many regions of the tropics. Quinine was isolated from the bark in the early 19th century and was obtained, for example, from the bark of C. pubescens and C officinalis in relatively large amounts. The structure of quinine was not established until 1951.
However, the bark was used for various ill-defined forms of “fever” until in 1880 LaVeran identified the organism responsible for the illness — eukaryotes from the genus Plasmodium. In 1897-1898 Ronald Ross and Battista Grassi demonstrated the life cycle of the parasite and its dependency on the Anopheles-mosquito were. Only at this stage was it possible to understand the mechanism of action of Jesuits’ powder, and this in turn allowed a rational phytotherapy using the isolated active ingredient, quinine. Since then a large number of quinine derivatives have been isolated. Another core ingredient is quinidine, a classic anti-arrhythmic drug.
This example demonstrates the long development process from initial observations (whether they were by the Jesuits or indigenous Americans) to several natural products used biomedically.
Wormwort, Epazote Chenopodium ambrosioides / Chenopodiaceae
The wormwort or wormseed is also known under its alternative Latin name, Teloxys ambrosioides, or its Aztec name, epazotl (modern mexican Spanish: epazote). It is another species with a long tradition of uses. Fascinatingly, it is used both as a spice for a variety of dishes, especially ones with Mexican black beans (frijoles), and as a medicine for gastrointestinal parasites. The name seems to be derived from the Nahua term for skunk, epatl, and relates to the rather unpleasant smell of the plant (some liken it to the urine of a skunk). As long ago as the 16th century, Fray Bernardino de Sahagun mentioned “epazotl” as a food. Today it is one of the most popular spices and is used medicinally as a vermifuge (to treat worms) as well as to reduce flatulence. It was included in many pharmacopoeias, including the ones of Mexico, the United States, and many European countries, but because of the toxic side effects (mostly of the essential oil) and a lack of evidence in support of its vermicidal effects, it has now been substituted by synthetic vermifuges. Once used worldwide as a medicine, it is today largely restricted to its region of origin, especially Mexico, where epazote is an essential part of the local cuisine and medical tradition, and also a powerful symbol for Mexican identity.
Zoapatle Montanoa tomentosa / Asteraceae
Zoapatle or cihuapatli (cihuatl, woman and patli, medicine) is a classic example of a women’s medicine and the main uses have been retained by the indigenous Mexican populations at least since the Aztec period. Sahagun described the use of its root for inducing labor (“which has the virtue to bring the new-born out”) and in combination with the Mesoamerican sweatbath temazcal. It was so famous with the midwives of this period that it was rapidly accepted as a medicine for regulating “menstrual irregularities” by the Spanish conquistadors. However, the very nature of its use made it a very controversial remedy, and even though it is still commonly used in Mexico, it is not currently used in biomedicine.