The waters of the Amazon fluctuate as much as 45 feet in years of heavy rainfall, meaning plants growing along the river are alternately subject to flooding in the wet season and dry soils in the dry season. To tolerate these extreme habitats, some Amazonian plants have evolved adaptations to both situations. A perfect example is the Amazon water lily (Victoria amazonica), which has adjusted its annual life cycle to the rise and fall of the rivers by growing rhizomes and new leaves from seeds, flowering at high water, fruiting as the water recedes, and surviving low water levels as seeds—each one surrounded by an impervious seed coat that protects against desiccation.
In our continuing discussion on botanical taxonomy, we now delve into the discovery of the Brazil nut and explain where it fits into the plant kingdom. But don’t be mistaken—when I say “discovery,” I am referring to the scientific naming and classification of the species rather than the first physical discovery of the plant by humans. Nearly all economic plants were discovered and given common names long before scientists became aware of them.
As part of their travels to the New World (between 1799 and 1804), the German scientist Alexandre von Humboldt and the French botanist Aimé Bonpland traversed the Rio Orinoco, making natural history collections and observations along the way. At one point, they subsisted for three entire months on rancid chocolate and plain rice alone. Fortunately, these explorers came upon Brazil nut collectors, allowing them to feast on great quantities of Brazil nut seeds. They were also impressed by the magnificent tree itself, and so interested in obtaining its flowers that Humboldt offered an ounce of gold to any one of the collectors who could find and retrieve them—an impossible task, as fruiting Brazil nut trees were not in flower.
Nevertheless, the expedition made collections of the leaves and fruits, and Bonpland described the species as Bertholletia excelsa Bonpl. Although the authorship of this species is sometimes attributed to both Humboldt and Bonpland, it is clear that the latter is the author of the scientific description and name for this species. Bonpland dedicated the genus to Claude Louis Berthollet, a chemist who, along with Antoine Lavoisier, developed a system of modern chemical nomenclature.
Last week I discussed how the scientific names of plants change because of the law of priority. This time around, I explain how names change due to differences in species concepts, leaving the question of “what is a species” for future posts. For now, all you have to know about this complex topic is that a species is a population of plants that plant taxonomists recognize as being different from other populations. In addition, a useful species concept is one in which the morphological and molecular characters used to circumscribe species are also apparent to non-botanists. For example, non-botanists should be able to identify one species from another based on character differences.
In simplest terms, botanists are classified as those who recognize relatively small differences in plant populations as distinct species (splitters), versus those who consider certain kinds of variation to be normal within a species (lumpers). Many animal species include considerable variation in their circumscription as evidenced by the recognition of humans, dogs, and cats as single species. Generally speaking, zoologists have broader species concepts than botanists with the latter tending to split species more than the former. Botanists with different philosophies about splitting and lumping may cause name changes.
Memorizing scientific names can be an exasperating experience for nature lovers, especially when learning that those names occasionally change for complicated reasons. Last week I discussed the structure of scientific names based on the Linnaean binomial system. Now, I explain some of the most common ways scientific names change based on the law of priority, a rule stipulating that the first name validly published for a species is the correct name for it. Be aware that this may not be the most beginner-friendly topic, but it is integral to understanding the complex business of botanical nomenclature.
The rules of botanical nomenclatures are formalized in the International Code of Nomenclature (ICN), which is updated every five years at the International Botanical Congresses; the most recent such congress took place in Melbourne, Australia, in 2011. Although the ICN defines the rules for naming plants, it does not provide guidance for determining if a species is distinct from other published species, thus justifying a new name. The taxonomic validity of species is determined by reviewers of scientific papers in which names are either proposed or changed, as well as by the acceptance of the names by the scientific community in their scholarly works such as Floras.
Understanding the botanical naming system can be a difficult task for beginners—classification hierarchy, plant name changes, and name selection all have to be taken into account. But rather than tackle this important botanical puzzle all at once, we instead begin with the most basic piece: species names. The rules discussed here apply not just to the Brazil nut family, but to every plant found in all the world’s habitats, and have much in common with zoological nomenclature.
A species name consists of two parts—Gustavia augusta, for example. The first part of the name is the genus and the second is the species epithet, each of which is either in Latin or Latinized words from other languages, especially Greek. Known as binomial nomenclature, Carl Linnaeus is considered the first to use this system, which he employed in his Species Plantarum—long regarded as the starting point for plant nomenclature. As such, a name used in Species Plantarum has priority over other names published for the same species at a later date.
Gustavia augusta L. was published in a later, 1775 edition of Species Plantarum, but afterward the same species was published as Gustavia antillana Miers in 1874. In this case, Gustavia augusta is considered the correct name, and G. antillana is accepted as a synonym.
In telling the tale of one of the great Amazonian explorers, C.V. von Martius, I wrote that, “… Martius was carrying with him 20,000 botanical specimens which served, and continue to serve, as the basis for countless botanical studies, including Flora Brasiliensis which remains the only published complete Flora of Brazil to this day.” To clarify, I was not suggesting that Flora Brasiliensis contains all Brazilian species, but that it is the only Brazilian Flora that included all documented plant species in Brazil at the time of its writing. In fact, there are at least twice as many species known in Brazil today as there were back then!
When I talk to other botanical enthusiasts about wildflowers of the northeastern United States, our conversations often return to the same question: “Where have all the spring wildflowers gone?” The most obvious response is that there are too many deer eating understory plants in our forests. However, that is only one of several reasons explaining the loss of spring wildflowers, among which is the presence of invasive plants which outcompete many species of our native flora. One of the worst invasives, the Japanese barberry—Berberis thunbergii DC—has had a major impact, leading me to rate it as one of the most noxious invasive plants in the northeast.
After seeing what I have to say, I would love to know if you can nominate an invasive species nearly as bad as this resource glutton!
Scott A. Mori is the Nathaniel Lord Britton Curator of Botany at the The New York Botanical Garden. His research interests are the ecology, classification, and conservation of tropical rain forest trees. His most recent book is Tropical Plant Collecting: From the Field to the Internet.
Studying plants in the field is the best way to acquire knowledge about them. Unfortunately, when a specialist does not live where the plants grow, it is difficult to study them in situ. In this modern age, the availability of digital photography and the internet makes it possible for local botanists to collect and photograph plants, then send the data and images to specialists. Although I prefer to see plants in their natural environments, new technology yields information that I could never have collected on my own!
One of my collaborators is Alex Popovkin, a Russian-born editor who works remotely from his small cabin in rural Bahia, Brazil. Alex has been passionate about plants since kindergarten, where he made daily observations of the development of a potted nasturtium planted by his teacher. He also observed the house plants his father cultivated on window sills in their St. Petersburg home. As a high school student in the early ’60s, Alex cared for tropical plants, and among other tasks penciled their Latin names on wooden labels at the Botanic Garden of the University of St. Petersburg as part of his work-study curriculum. His first botany mentor there was Dmitri Zalessky, the garden’s director at the time.
As mentioned in previous posts, my main research focus is the classification and ecology of the Brazil nut family (Lecythidaceae) in the New World tropics. The Brazil nut–the largest nut in a can of mixed nuts, for reference–and the cannon ball tree are the best known plants of this family, the former for its economic importance and the latter as an ornamental tree in tropical botanical gardens. Because I have been studying this group of plants for nearly 50 years, many people are surprised when they learn that there are still new species to be discovered.
For many years I had known of a large-leaved species of the Brazil nut family that had been collected in southwestern Colombia, but I was not able to identify the species; the few available collections were poorly prepared and the collection area was not safe for botanists to visit. Therefore, when I was invited to give a lecture at the fifth Colombian Botanical Congress in April of 2009, in San Juan de Pasto, I immediately accepted the invitation–this was relatively close to where the mystery plant grows and, more importantly, it was then safe to travel there. Coincidentally, the congress field trip was to the Reserva Natural Río Ñambí, a beautiful private cloud forest reserve known for the 29 species of hummingbirds found there, as well as for its spectacular plants, many of them epiphytes covering the trees. One of those trees happened to be the very plant that I had my eyes on for so many years!