PREPARING PLANT COLLECTIONS
Plant collections serve as an important instructional tool in many plant orientated courses. They give the student firsthand experience in preparing plant specimens for the herbarium. While identifying plants by the use of "plant keys", the student learns both how to use the key, and how to recognize the important morphological characteristics of different plant taxa. In addition, while collecting in the field, the student is given the opportunity to observe how plants react with both the physical environment and with other organisms (both plant and animal) to form distinct communities.
The best plant collections are those which are neat, orderly, and which give detailed information both about the plant itself and the community from which it was extracted. The following discussion is provided here to help the student realize these objectives in his own plant collection.
I. COLLECTION OF PLANTS
The proper time to collect plants is when the plants are actively producing fruits and/or flowers. The entire plant including the shoots, roots, flowers, and fruits should be collected. Incomplete or senescent specimens are often very hard to identify with a taxonomic key. Incomplete specimens may lack an organ needed in the key, while old senescent plants tend to disarticulate when dried, leaving you with a pile of debris instead of a recognizable specimen.
Quite a bit of plant material may be destroyed during keying. Always collect sufficient material to provide specimens for dissection as well as for the herbarium.
II. PRESERVATION OF PLANT SPECIMENS
Plant specimens are generally preserved by drying. A "plant press" (see Figure A-1 in Gould, 1968) is good for drying plants because it prevents undue wrinkling and shattering of the specimens as they dry. Grasses my be air dried using a plant press. However, some type of forced or convectional air will dry the plants faster and retain the specimen color.
Proper use of the plant press is imperative if satisfactory results are to be obtained. The following series of steps should yield good results.
Instructions for Plant Pressing, Mounting , and Labeling
Pressing the Plants
1. Collect the plants that are typical of the species you would like to press (enough
for 2 herbarium sheets).
2. Collect all of the plant; roots, stems, leaves, and inflorescences (except for trees
and shrubs). Tree and shrub specimens are collected by clipping the last 12 inches
of the leafy branch with flowers and/or fruits.
3. Clean the loose soil from the plant’s root system.
4. Fold or cut plants so that they fit within a 21" x 17", single sheet, of newspaper.
5. Record the collected specimens with the number you record in your field notebook.
6. Separate the sheets of newspaper and neatly place the plant in between a folded
sheet of paper (change newspapers everyday if plant specimen is very wet).
7. Spread out the plant parts because you want the plant to dry without molding
or changing color. F.Y.I. newspaper absorbs excess plant moisture.
8. Place the newspaper between two pieces of cardboard.
9. Repeat this process, with one species per sheet, until the plant press is full.
10. Secure the press with straps. A tight press yields a high quality specimen.
11. Place the press in front of a fan for 96 hours.
12. After 96 hours (if dry ─ when held up they do not fold up), you may remove
the plants and mount then on paper using glue.
13. Identify the plant material.
14. Mount plants on paper as described below only as assigned.
After the plant specimens have been pressed, dried, and identified they are ready to be mounted.
1. Herbarium sheets, standard (white) tag or poster board are recommended for mounting sheets. Although herbarium sheets usually have to be ordered through biological supply outlets, poster board can be purchased at most stores selling office and school supplies. If you use tag board, four mount sheets can be cut from one board if each sheet is cut 11 inches by 14 inches. Three sheets can be cut if each sheet is cut 11 ˝ inches by 16 ˝ inches.
2. Placement of specimens is easy if plants have been pressed properly. The specimen should be placed upright with roots near bottom and should provide a pleasing appearance.
leave room in the lower right-hand corner for a 3" ´ 5" mount label.
3. A transparent glue (i.e., Elmer's glue) is preferred to spot weld the specimen to the sheet. Small weights, such as lead casts, large nails, heavy washers or large nuts will hold the plant in position while the glue is drying.
4. Each mount requires a label in the lower right hand corner. The label must be properly filled out (see below, and examples). Include collection date, plant name and authorities, associated plants, sun exposure, soil characters, collector, and collector's number etc.
1. Your field book is to record data about the plants and the collection site. The data should consist of at least the following parameters:
habitat geographic locations (GPS coordinates when possible)
elevation country, state, county of collection
associated species soil
plant height flower color at collection time
date of collection collector(s) and collection number
soil moisture relative abundance
2. The field book should have more data than your labels. This should be your memory and be prepared at the time and site of the collection.
3. All specimens of a single species receive the same collection number for a specific site. New locations require new numbers, even for the same species.
4. Data from the field book is used when making identifications and preparing labels.
Blank plant labels in WordPerfect format
LABEL: S.M. Tracy Herbarium Texas A&M University Plants of Texas, USA Brazos County Fumariaceae Corydalis micrantha (Engelm. ex A. Gray) White Corner of Barron Road and Vistoria Avenue in S College Station. open pasture, flat, elevation 320 ft., disturbed. Sandy loam soil, mesic. Plants about 25 cm tall, annual, flowers yellow. Associated genera Ranunculus muricatus, Northoscordum bivalve, and Medicago polymorpha. N 30.64773 W 096.29624 Ken Anderson 21 17 Feb. 2006