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This
means that we can house many more species than a greenhouse or botanical garden.
The largest herbarium in the United States has close to 10
million specimens. The UC Davis Herbarium has ca. 250,000 specimens.
How are herbarium specimens used? Each
specimen consists of both the dried plant specimen and a label. The dried plant is
used as an aid in plant identification. People compare their plant
samples with herbarium specimens to confirm that they are using the right plant
name. Evolutionary biologists also use the dried plants in their studies
of plant form. Biologists can look at specimens of a species from
throughout its geographic range and measure all the plant parts. Such
measurements are used in plant guidebooks worldwide. DNA: Over the past 20 years, another important use for
the dried plant on herbarium specimens has
developed. DNA can be extracted from the dried plant material, and this DNA is
analyzed to find out more about the relationships between plant groups.
The label on each specimen has information such as the plant name, the name
of the person who collected the plant, and when and where it was
collected. Often, information on the plant community it was growing in
(such as grassland, pine forest, etc.), the soil type, pollinators, or plant
uses are also noted on the label. Therefore, the label contains very important
data on when and where species occur and this information is included in plant
guidebooks worldwide. Herbarium specimen data can be used to track the
spread of noxious weeds and the demise of rare plant species. Herbarium
specimens are a historic record of where and when plant species have
grown. |
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Specimen of Monardella leucocephala
(an extinct species). Photo by Bill Rice. |
What types of plants are represented in the UC Davis Herbarium?
We
have algae, lichens, bryophytes, ferns, gymnosperms, and angiosperms
from all over the world. However, most of our collections are
angiosperms from California and other parts of the United States,
Mediterranean Europe, Mexico, and Ecuador. We are known for our
collections of California weeds and vernal pool plants, and our
grass collection is the finest in the state. Due to the research
interests of the previous two directors of the Tucker Herbarium,
we have a world-class collection of Quercus (Oaks) and
Euphorbiaceae (the spurge family). At the present, we have about 250,000 mounted and unmounted specimens.
Joe DiTomaso (Weed Scientist)
identifying a plant in the herbarium. Photo by Bill Rice. |
Who uses the UC Davis Herbarium?
Researchers and students from over 20 campus departments and
three colleges at
UC Davis use our collections and library. Three of our most frequent users are
UC Cooperative Extension, the UC Natural Reserve System, and the California State Veterinary Diagnostic Lab which sends us
poisonous plants to identify. Most
of our off-campus users consult us by phone or mail. This is
the case for UC Cooperative Extension farm advisors who send
us plants for identification from all over California. Many state and federal
agencies use our collections, as do private consulting firms and non-profits
such as the Nature Conservancy. Any member of the public is welcome to use the
UC Davis Herbarium or request our help.
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How are herbarium specimens prepared?
| Collecting:
Herbarium specimens are dried and pressed in a plant press like
the one shown at right. Freshly collected specimens are placed in
newspaper between blotting paper and cardboards. The wooden press is
at the two ends and is held tightly closed with straps. |
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| Mounting:
After the plant samples are pressed and dried, they are mounted with labels on
special archival 11 x 17 inch paper. The mounting process involves
detailed work to make certain all identifying characteristics are placed
appropriately on the paper.
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| Herbarium specimen:
The completed specimen |
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| Herbarium folder:
Once the specimens are properly mounted, they are placed within
folders. |
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| Herbarium case:
The folders at the UC Davis Herbarium are placed within metal cases and
arranged alphabetically by scientific name. |
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