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Processing of Specimens

Processing dried specimens involves four steps:

1. Identification,
2. Label preparation,
3. Mounting, and

The first three are critical in producing a high-quality, final product.

Specimens need to be correctly identified. If you have any doubt, send a duplicate specimen to a taxonomic expert for confirmation. Negotiate and document a definite time to complete the identification when you make the request, otherwise you may wait a long time for the information. If the taxonomist will not be paid, it is usual to collect duplicates and offer some of the collection to keep. If the taxonomist is paid for the work, then all the specimens are usually returned to the collector, unless specified otherwise. When the material is returned, the positively identified specimens will be an important addition to your herbarium. Plants should not be processed until the identification is certain.

To identify plant specimens you will need a basic knowledge of taxonomy and nomenclature, familiarity with the morphological characteristics of different plant families, access to a library of regional floras (and taxonomic papers to supplement these floras ), and the ability to use a herbarium reference collection.

Identification technique

The following suggestions may help in the identification process:

1. Try to have more than one plant of a species available to dissect, or have extra flowers on hand.
2. Dissect fresh material if possible, or use thoroughly moistened dry material.
3. Have at least two different identification keys, since each may use different methods to arrive at genus/species.
4. As you proceed down the key, note the numbers so you have a record of the route taken.
5. Double-check all identifications using the key and herbarium specimens if available.

The correct identification of a specimen is not always easy. A significant portion of the local flora may belong to taxonomically difficult groups. For example, many of the Asteraceae, Cyperaceae, Poaceae, Potomogetonaceae, and numerous genera such as Astragalus, Castilleja, Draba, Lupinus, and Salix are difficult to identify

Labeling

 Each specimen collected should be labeled and the labels should contain  the following information

• The flora
• The scientific name
• Vernacular name
• Local name
• Locality
• Habitat
• Description of the plant characteristic
• Economic importance of the plant
• Frequency – the seasons when is the plant common
• The collectors name

Mounting

Mounting the pressed plants involves skill and patience but can provide much satisfaction when the task is complete. Mounting techniques have changed considerably in the past 10 years, as has the quality of mounting supplies.

All supplies should be of museum quality since the longevity of the specimens is directly related to the substances with which they are in contact.

Before starting, have ready acid-free mounting paper, cardboard sheets, glue in small, flexible, plastic squirt bottles, wooden spacer blocks, weights, needle and linen thread (optional), paper seed envelopes (Kraft coin envelopes), and identified specimens with completed acid-free label.

The best work area is a large surface such as a high counter or a drafting table with an appropriately sized stool. Ideally

this area should be separate from the herbarium to prevent insects from being introduced into the main collection. Natural light makes the job more pleasant. Remember that the specimen(s) may have to be removed at some time and large amounts of glue make this task impossible. The following suggestions should ensure a high-quality collection:

• Wear appropriate PPE; mounting can be a very messy business.
• Arrange supplies so the work can proceed in sequence, from left to right, or vice versa.
• Place the specimens to be mounted at one end of the table, with a garbage can nearby ready for waste plants or dirt.
• Glue the label to the bottom right corner of the herbarium sheet.
• Annotation or determinavit labels, if present, should be placed directly above or to the left of the main label. If they are too far apart, the incorrect identification on the main label may be used because the smaller annotation label is not noticed.
• Run a bead of glue only along the top edge of the label. Field labels or other information can be folded and affixed underneath. Make a note on the label if any extra information is glued under the herbarium label (e.g., additional information beneath). These should be rotated in location so you don’t end up with a bulge on a stack.
• Leave space on the sheet for seed and fragment packets and for accession stamp/number—usually near the upper edge.
• Remove any soil clinging to the roots or stems. Gently crush with the blunt end of the probe, rub the roots between your fingers over the garbage can, or lay on a flat surface and tease with a dissecting probe.
• Use scissors or pruning shears to trim large specimens to fit the sheets.
• Make sure that important parts are not cut off.
• Sometimes the last particles can be dislodged by tapping the root gently on the inside of the garbage container. Try this only on robust specimens,as it will damage others.
• Place a sheet of mounting paper on a cardboard sheet. The cardboard makes it easier to move the finished product and stack it for drying.
• Arrange the plants on the mounting paper.
• Vary the arrangement of specimens on the sheet to avoid otherwise sloping stacks that will cause problems in storage (brittle plants will break under lopsided conditions).
• Salvage any valuable loose material, such as seeds or flowers, and place them in paper or wax paper packets (see Figure 6 for folding method).
• Glue fragment packets near the upper edge or sides of the sheet after the specimens are mounted.
• Avoid placing anything right at the edge of the mounting sheet, as it may stick out and get damaged. Leave approximately one and a half inches around sides for ‘‘finger space’’ to allow the sheet to be picked up without damaging the specimen.
• Hold the specimen down with weights, such as plastic-coated lead bars or large metal washers, until the glue dries. You can dip the washers in acrylic floor wax before using.
• Attach the specimen to the mounting paper with thin ribbons of glue running from the paper across the plant part to the paper .The glue should not cover any parts necessary for identification, for example, the nodes and ligules of grass

For aquatic specimens  Aquatic plants require special care when the mounting sheet is removed from the newsprint. Specimens may adhere to the newsprint in several places.

• If specimens have been dried on thin mounting sheets, the paper may have become wavy during the drying process. You may want to glue the thin sheet to another sheet of mounting paper for more rigidity.
• Affix labels so that important parts are not obscured, and place glue where required

Accessioning (Cataloguing)

The final step before filing the mounted or packaged collections in the herbarium is to assign accession numbers and to record the specific associated data in a computer-based file or an accession book. The amount of information recorded varies, but the more information you record, the more valuable the specimen is for future researchers.

 These records become the index for the herbarium collection. In some larger, more progressive institutions, the labelling program serves a dual purpose, and accession numbers are assigned and recorded automatically when the labels are produced. This system saves time in a large collection. An accession book is adequate for a small collection. Accession numbers are assigned chronologically as specimens arrive, for example, starting with number 000001.