Collecting and Pressing Plants

Html Editors: Dr. Jochum Wiersma & Tracy Allrich

One of the most useful references for proper plant identification is a collection of dry plant specimens. Collection of dry specimens are usually found in educational or research institutions (herbarbia), but can also prove useful on an individual basis for a farm or region.

  1. Value of Collecting and Pressing Plants
    1. Very helpful way of learning to know plants
    2. Can secure plant specimens when they are in flower and identify them later.
    3. Can Check with an expert if you are not sure if identification.
    4. The pressed specimen serves as a useful reference to help identify other specimens found or received later for identification.
    5. A collection of plant specimens provides a record of plant species of an area.
  2. Equipment needed for collecting and pressing plants
    1. Digging tool to collect root samples or dig entire specimen plant if desired.
    2. Pocket knife or pruning shears to clip off desired portion of plant.
    3. Plastic bags of assorted sizes to keep plants from drying out until they can be pressed.
    4. Sheets of folded newspaper to place plants in for pressing.
    5. Cardboard and blotter sheets for insertion between specimens in plant press.
    6. A plant press constructed of two sheets of plywood or a lattice design of wood strips nailed together and bound with straps or a rope to apply pressure.
    7. A field notebook to take notes about the plant specimen. Include data collected, location where collected, notes on size of plant if entire plant is not collected, type of root, flower color, whether plant has milky juice, odor, or any other characteristics that will be lost when the plant is collected.
    8. Index cards to label mount. A camera.
    9. If possible, take a closeup colored slide of the plant before collecting, include a second closeup slide of identifying characteristics, if possible.
  3. Collecting Plants
    1. Locate and Collect a representative plant, or collect a range of flower color, type, etc.
    2. Collect a plant with flower or fruit parts present if possible.
    3. Collect roots of plant or if roots are too large, note carefully type of root system.
    4. If plant is dioecious, collect both male and female plants, if possible.
    5. If plant has basal leaves which are different from leaves on stem, collect samples of these -- or collect whole plant.
    6. If possible, arrange to collect plants in vegetative as well as flowering stages.
    7. Number the plant by taping a tag to plant or numbering the plastic bag in which plant is placed. Use a corresponding number in plant notebook to record details about plant.
    8. Do not dig or unnecessarily destroy rare or uncommon plants. Plants like showy ladyslipper, or Jack-in-the-pulpit should be photographed rather than collected unless plants are plentiful in the location or if to be used for a worthwhile educational display. Obtain permission before you collect plants on private property, State Parks, etc.
  4. Pressing Plants
    1. Place the plants in a once-folded newspaper (approximately 15 1/2 X 11 1/2 inches in size). Number the newspaper to correspond with the plant.
    2. Arrange the plant so the floral parts and other identifying characters are well displayed.
    3. Place the folded newspaper with its plant specimen enclosed between blotters of approximately the same size as the folded newspaper and enclose in plant press. (Plant press and divider cardboards should also be this size or slightly larger).
    4. Apply weight or pressure to plant press by use of weights, straps or tightened rope.
  5. Drying Plants
    1. Specimens should be dried before mounting them for permanent storage in order to obtain a durable sample.
    2. Place plant press in a drying oven for 24 hours at a temperature of 100-125oF. Large fleshly specimens may need 43 hours of drying time.
    3. If a drying oven is not available, dry the specimens in a warm and dry environment (indoors). Replace newspaper and blotters as needed if they become too moist (every day or as needed). Dry for 3 to 5 days.
  6. Mounting Plants
    1. Materials Needed:
      • glue (such as Elmer's)
      • water
      • brush
      • piece of 10" x 15" glass or cookie sheet
      • scrapbook paper sheets (100% cotton fiber) or good quality poster board (16 1/2" x 11 1/2").
      • tweezers (2 pairs)
      • waxed paper
      • linen strips
      • labels
    2. After the specimen is dried you can proceed to the final mounting. Procedure:

3.      Dilute glue with water (2:1) and spread it evenly over the glass or cookie sheet using a brush.

4.      Place dried specimen on glue-covered glass and press softly to assure complete and uniform gluing.

5.      Lift plant specimen from glass with two pairs of tweezers and carefully place it on the scrapbook paper sheet.

6.      Place and glue identification label (see model) at the lower right hand corner of the page.

7.      Cover plant specimen and scrapbook paper sheet with waxed paper; place blotter on top and underneath the scrapbook paper sheet.

8.      Uniformly press with books or bricks for one day.

9.      If necessary, a few gummed linen strips could be used for better fixing of the specimen to the herbarium paper.

Remember: Only one specimen should be mounted per sheet.
Dry Specimen Label Herbarium of
Somewhere, Usa Scientific Name:

    • Common name(s):
      Latin name:
      Family:
      Growth cycle:
      Habitat:

Collected by:

Date:

Place:

 

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Additional Comments:

  1. Methods for Mounting Large Weed Specimens

In many cases, weed specimens will be too large to mount on the sheet. There are several solutions to this problem.

    1. Bending Plant
    2. Sectioning plant: Omitting duplicate sections of plant
    3. Sectioning plant: Cutting plant into sections and mounting each


Maker Your Own Plant Press

A good plant press can be built from thin plywood, strips of wood cut from an apple box, create, or other thin, strong wood. You also may obtain 48 - inch wood lath from a local lumber yard. Make the press the standard size and construction. Standard size is 12 inches wide and 18 inches long. Slatted construction is best so that plant specimens can dry properly. You will need:

  1. Four pieces of wood 18 inches long, 1 inch wide, and 1/4 inch- 3/8 inch thick.
  2. Sixteen pieces of wood 12 inches long, 1 inch wide, and 1/4 inch thick.
  3. At least 32 small nails (smaller than shingle nails) or 1/2 inch screws.
  4. Hammer and square for assembling. Use half of the material for each of the two sides of the press.
  5. Two straps or ropes about 4 feet long to bind the press.
  6. A supply of newspaper for pressing.
  7. A dozen or so pieces of corrugated cardboard 12 inches by 18 inches. These can be cut from clean cardboard boxes.
  8. A supply of several sheets of heavy blotter paper 12 inches by 18 inches. These can be cut from felt building paper that is not tarred. Succulent plants may need blotter change every day. If blotter paper is not available, you can use additional folded sheets of newspaper between specimen sheets.



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