Making Herbarium Specimens

 

In this activity, you will be collecting leaves that display the characteristics that were pointed out in your Taxonomy laboratory.  Once you find a leaf that is an example of a botantical characteristic of interest, you will mount it in the same fashion that a botanist would.

Selection of Specimens:     

1. Collect only reproductive plants.  Do NOT collect specimens without flowers and/or fruits.
2. Select specimens that illustrate as completely as possible the characters of the various parts of the plant.  Whenever available, roots, tubers, bulbs, stems, leaves, flowers and fruits should be represented.  There should be a generous supply of flowers and fruits to be used in the study of the specimen.
3. As a general rule, small plants or ones which by folding can be made to fit a herbarium sheet (12 x 18 inches) should be collected entire.  For very small plants, collect multiple individuals.  Large plants (shrubs, trees) should be represented by branches possessing flowers, fruits, and leaves.
4. Don’t collect in national or state parks without a permit.
5. Avoid unnecessary trampling of adjacent plants while collecting.  Be environmentally sensitive!

Collection and Preservation 

1. Care of specimens between collection and pressing.

Most plants may be kept fresh for several hours if held in a plastic bag.  Add a few drops of water to a Ziploc bag to raise the humidity and allow transpiration.  Freshness of specimens may be prolonged by refrigeration, but do not freeze.  Most students find fresh material easier to identify than when dried. Saving extra portions for later identification is a good idea.  THE BEST METHOD IS TO PRESS IMMEDIATELY AFTER COLLECTION.  

Useful accessories:

Clippers- for woody plants

Digging tool- to excavate roots for all herbaceous plants!

Large plastic bags- enough for your various stops and types of plants.

Masking tape- plants put into plastic bags should  be taped and assigned a number.

Pencil or ball point pen- your collection numbers and entries should be made in ink or pencil that will not run if they should get wet…it sometimes rains in the field.

Handlens- required for identifying plants. 

2. Pressing specimens

When pressing specimens, arrange the material as naturally as possible and avoid excessive overlapping of parts.  Spread out inflorescences and flowers to show as many details as possible, and attempt to show both leaf surfaces.  Parts too bulky (pine cones, acorns, large dry fruits) should be labeled with tags and kept in paper bags. 

Always number the newspaper sheet prominently in accord with the number designated for the specimen in your field notebook.

The best order of materials in a plant press are:

            Cardboard: blotter: newspaper sheet: blotter: cardboard

Close the press and tighten straps as tightly as possible. 

3. Drying specimens in the plant press

If the plant press contains an adequate number of cardboards and blotters and is placed in or on a drier, it should not be necessary to change the blotters.  Most plants will dry within two or three days. If the press is not placed in a drier, the blotters should be changed periodically.  Plant specimens should be removed when they are dry and placed in a dry, insect-proof case.

FAILURE TO CHANGE WET BLOTTERS OR TO ADEQUATELY DRY SPECIMENS WILL RESULT IN MILDEW FORMATION AND UNACCEPTABLE SPECIMENS. 

4. Field Information

When making collections record the following information:

1. Date
2. Locality (exact directions and elevation)
3. Notes (Field conditions, plant description)
4. Name

Note: for a name to be correct, the author or authority must be included. This information can be obtained from the Missouri Botanical Garden web page (www.mobot.org). Click on W3 tropicos from the menu on the left of the page, and type in the species of interest in the box and hit return. The next page will give you the genus, species and the authority).

 

You will submit up to 15 specimens.  Part of the fifteen should include examples of

·         Parallel venation

·         Simple pinnate

·         Compound pinnate

·         Simple palmate

·         Compound palmate

Note the venation patterns for these samples in the Notes section.  Make two of each if you would like to keep your specimens, as your submitted specimens will not be returned.  You will be graded on the quality of your collection.