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Guide
to herbaria online
In an era of computerized databases, digital
imaging, molecular analysis and DNA sequencing, it seems little
short of quaint that research institutions would continue
to place so much importance on the collection and preservation
of dried plant specimens. Herbarium techniques have changed
little in several centuries: collectors still gather pieces
of plants, flatten and dry them, and then glue or tape them
to sheets of stuff paper, labeling each with the date and
place of collection. To botanists, however, even the most
sophisticated electronic representations cannot substitute
for the real thing. "Each and every herbarium specimen is
a voucher documenting a plant growing at a certain site at
a certain time," according to a fact sheet produced by the
University of California. "As such, herbarium holdings worldwide
collectively provide the raw data underpinning our scientific
knowledge of what kinds of plants exist, what their diagnostic
features are, what range of variation exists within each,
and where they occur. If herbaria ceased to exist, our monographs
and floras would consist of hypothetical abstractions, no
longer tied to the concrete data from which they were derived."
Access to herbarium collections at most institutions generally
is limited to professional researchers. Amateur botanists,
however, may increasingly take advantage of modern communications
technology to examine plant specimens from around the world.
The following Web sites serves as a good starting place for
those wishing to explore virtual herbaria.
For those undertaking such an excursion, it
may be helpful to understand a few common terms used by botanists
and taxonomists.
- botany The scientific
study of plant life.
- family A group
of plants sharing common features and distinctive characteristics
and comprising related genera; the taxonomic category above
genus and below order.
- genus (pl. genera)
A group of closely related species. The taxonomic category
ranking above a species and below a family.
- herbarium An organized
and cataloged collection of plant specimens. 2. A specialized
room or building with constant levels of temperature, moisture
and restricted light where plant samples are stored in a
designated pattern in large light proof cabinets, allowing
samples to remain useful and to be retrieved for study and
comparison for centuries.
- herbarium specimens (alt.
herbarium samples, alt. herbarium mounts) Pressed, dried
plants fastened to sheets of paper, which serve as permanent
records of a species as it appeared at a given time and
place.
- order A category
of taxonomic classification ranking above the family and
below the class.
- species A population
or series of populations whose individuals have the potential
to freely breed with one another and that is discontinuous
in variation from other populations or series of populations;
a fundamental category of taxonomic classification that
ranks below a genus.
- taxon (pl. taxa)
A group of genetically similar organisms that are classified
together as a species, genus, family, etc.
- taxonomy (adj.
taxonomic) The classification of organisms based on genetic
similarities.
- type specimen By
accepted convention, a single specimen of each species is
designated as the "type specimen." The type specimen gains
its importance in its role of anchoring nomenclature. It
is the name-bearer, providing an unequivocal way of linking
a name (and abstractions connected to that name) with a
single representative of the species. All other specimens
are linked to the name secondarily, by virtue of their acceptance
as members of the same species.
Glossary sources: GardenWeb,
University
of California |
