Most BRIT research is generally described either as floristics (what species grow where) or as systematics (names and definitions of species and genera and their evolutionary inter-relationships). The whole field often is referred to as taxonomy. BRIT botanists work primarily in the herbarium, field, and library, and they collaborate with other institutions and universities on molecular studies requiring specialized equipment and techniques.
In floristics, BRIT scientists study "what plants grow where" (see previous page).
In systematics, BRIT scientists work to ...
* clarify definitions of species (or, in many cases, to recognize the existence of species previously unknown to science, see new species),
* make hypotheses about evolutionary relationships among species, genera, and families, and
* apply consistent and correct nomenclature.
Much of BRIT research falls into the following categories:
* Floristic treatments
why: To document geographic diversity and to provide a format that allows plants to be identified and associated with pertinent information.
Floristic treatments summarize information about plant species (the flora) that grow in a particular area, usually providing at least short descriptions and a means of identification. The area may be a local park, a county, a state or portion of it, or a larger geographic or political region (as in "North America"). For larger areas, the data probably are derived primarily from accumulated herbarium collections; for smaller areas, intensive field surveys may be required.
* Distribution records
why: To provide current information on geographical diversity.
When a species is first discovered in a state or other region, it often is reported in literature. The discovery might reflect a recently expanding geographic range (as in many non-native weeds) or simply the occurrence of a native species that is relatively rare (not previously encountered) in the area concerned. Such information eventually is incorporated into floristic treatments.
* Definitions of species and genera: One species or two? Two species or one? One genus or two?
why: To provide the basic 'units' necessary to fully and accurately describe biological diversity.
Variants within what has been recognized as a single species often prove to be justifiably treated as distinct species. Such variants might have been named as "varieties" of the species, or they might have been completely unrecognized and unnamed. In other cases, the distinction between two species might prove to be untenable, resulting in both species being 'lumped' into a single one. Evidence to support these kinds of decisions comes mostly from morphology, geography, hybridization, and chromosomes.
* Species new to science
why: To provide the basic 'units' necessary to fully and accurately describe biological diversity.
These may be based on new discoveries, often in a newly-explored area with unusual habitats. Or, a new species may have been collected many times previously but unrecognized as a distinct species (usually 'lumped' with some other species and identified as that species) —essentially the same as "two species rather than one" as above. See New species described by BRIT scientists.
* Evolutionary relationships
why: To allow greater predictability of features of a species or group, based on the assumption that closely related species have greater similarity because of common ancestry.
Most evolutionary studies involve 'reconstruction' of the evolutionary history, represented by a branching diagram (”tree”) that shows a common ancestor and its descendants. The tree might show relationships among species or among genera or families. The most reliable data are nucleotide sequences in DNA or RNA molecules that come from the nucleus or chloroplasts within cells.
* Classification
why: To provide a means of consistent communication about evolutionary relationships and/or similarities.
In order to show relationships within a group of species (or genera), they are grouped into hierarchical categories and given formal names. Ideally, the hierarchy of relationships reflects evolutionary relationships, based on the best available hypothesis. The classification itself sometimes may represent the best available hypothesis of relationships.
* Nomenclature and typification
why: To ensure that names of plants are as stable and as clear in concept as possible. Clarity of communication among all users of botanical information is essential.
Botanical nomenclature is based on the 'principle of priority' (the first validly published name for a species or genus is the correct one) and various other rules. Names of new species must be accompanied by a 'type'—an actual specimen cited in publication to anchor to the concept of the new species. Studies of nomenclature and typification usually have a legalistic and non-biological ring, but they are necessary.
HERBARIUM and LIBRARY: research tools in floristics and systematics
The BRIT-SMU-VDB Herbarium is an accumulation of approximately 1 million plant specimens collected by thousands of botanists over more than two centuries. Each specimen is labeled with geographic locality, date of collection, and ecological information. Herbarium specimens underlie the production of floristic studies, and provide evidence of species occurrence at a given location. About half of the collections are from Texas, Oklahoma, Arkansas, Louisiana, Alabama, Florida, and Tennessee. The Herbarium also has significant collections from elsewhere in the world, including those from special international projects such as the Philippines Flora and the Andes to Amazon Program.
The collections also provide the prime resource for studies of definitions of species and genera, new species, and evolutionary relationships and classification. Because DNA and RNA molecules may remain intact for many years, it is possible to obtain molecular samples from dried herbarium material.
The BRIT Library, with its large collection of books and journals, plays a major role in floristic studies, species identification, and nomenclatural research, and it provides information pertinent to definitions of species, classification, and evolutionary relationships.
Floristic literature from various parts of the world is especially significant as non-native plants become more and more diverse and abundant in North America. Historic volumes in the BRIT library often are essential in determining the correct name for a species. Valid scientific names of plants began to be published in 1753, and publications from the 18th and 19th centuries may have a direct bearing on establishment of the correct name. Journals and periodicals provide detailed reports of historical and current research. It can be a number of years before this information is summarized in books, and even then, critical details often remain only in the journals.
