Appendices & Glossary - Botanical Research Institute of Texas

COLLECTING HERBARIUM SPECIMENS/APPENDIX EIGHT
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are, what range of variation exists within each, and where they occur” (B. Ertter, pers. comm.). To work
with the actual specimens collected by Carl Linnaeus, Alexander von Humboldt, Asa Gray, or Charles
Darwin not only provides us with valuable data but also links us in a tangible way with the origins of
modern science and our own disciplines. 3) Further, because many plants are available for only a small
part of the year and because it is impossible to have live specimens of thousands of species from different
regions readily available for study, herbaria provide the only practical way to have material of numerous
species to compare and study—they thus are important research tools. Without a major herbarium
such as BRIT (the official abbreviation of the herbarium of the Botanical Research Institute of
Texas), a book such as this would have been impossible to produce. In addition, herbaria serve as a
record or repository of the voucher specimens upon which all taxonomic articles, books, and research
are usually based (Boom 1996). In this way, other botanists can recheck and judge the validity of the
work; these are critical steps in the scientific process. Also, because of the wealth of information contained
in herbaria, they are essential research tools not only for taxonomists, but also for those in such
diverse fields as ecology, endangered species research, entomology, environmental science, horticulture,
medical botany, mycology, palynology, and even forensics. 4) Finally, herbaria serve important
educational purposes. These range from their use by advanced undergraduates or graduate students
learning taxonomic botany to grade school students learning about the importance of plants and the
natural environment in their lives.
COLLECTING AND PRESSING SPECIMENS
One of the most important considerations regarding plant collecting is to secure appropriate permission,
whether on private or public land. This is critical in order to maintain a working relationship between
landowners and botanists. It is particularly important to be sensitive to such landowner concerns
as not damaging fences and properly closing gates. On public lands such as parks and wildlife
refuges, there are often strict collecting regulations with legal sanctions for not following these rules.
When selecting plants, collectors need to be sensitive to whether the plant to be collected is rare and
whether the population will be adversely affected by having one or several individuals removed. Because
populations of many native plants have been dramatically reduced by human activities, this
concern is more important now than ever before. A rule of thumb sometimes given is the “1 to 20”
rule—for every plant collected, there should be at least 20 others left in the population (Simpson 1997).
Collectors should also bear in mind that certain plants (e.g., cacti, orchids) have special legal protection.
Once it is ascertained that there is an adequate population for collecting, individuals representative
of the range of variation in the population should be chosen. Individuals with herbivore or pathogen
damage should not be ignored (Condon & Whalen 1983; McCain & Hennen 1986a, 1986b), and in
fact they should often be purposefully selected because such specimens are “information-rich” (J.
Hennen, pers. comm.)—that is, they often contain fungi, gall-inducing insects, or other pathogens and
show characteristic plant responses to such organisms. Ideally, the entire plant, including roots or
other underground structures, should be collected or, in the case of trees, shrubs, vines, or other large
species, ample material representative of the plant should be obtained. Slender plants can be bent or
folded to form a V, N, or even W shape on the sheet in order for them to fit (sometimes the point of the
V can be stuck through a slit in the bottom of the newspaper to hold the plant in place). For tiny
plants, it is appropriate to collect a number of individuals for each specimen needed. A general rule of
thumb is that the folded half-sheet of newspaper used in the pressing process (a full sheet torn in half)
should be reasonably well-covered by plant material without excessive overlap or crowding. The best
specimens have both flowers and fruits—while this is often not possible, all specimens should have
some reproductive structures (either spores, cones, flowers, or fruits). Because most taxonomic keys are
based on reproductive characters, sterile specimens are often useless. In fact, many botanists collect
extra flowers or fruits to use in identification. Seeds, fruits, or other parts that become easily detached
and are in danger of being lost should be put in small paper envelopes or bags and kept with the
specimen. Extremely large structures (e.g., pine cones, large fruits) cannot be pressed and have to be
carefully numbered (to match the specimen from which they were detached) and stored separately.
The highest quality specimens are probably obtained by carrying a lightweight press into the field