How to Make a Plant Collection
Before You Start . . .
First you need to consider what your purpose is in collecting plants, and what kinds of plants will serve that purpose. Many educational and craft uses of plant collections can be satisfied by cultivated plants and garden weeds. Before collecting plants in the wild, you should understand the legal issues of the ownership of the land and its resources, and the ethical issues of possible damage to wild plant populations and to endangered species. The California Native Plant Society's policy on collecting plants for educational purposes is well worth reviewing.
More and more the conservation ethic is to collect in the wild only when it serves a long-term research purpose, such as documenting what occurs in an area that is proposed for development, or discovering what grows in an area that has not been much explored. But these collections must be placed in permanent storage in order to serve their documentary purpose, and once in a scientific collection they can continue to contribute to science in many other ways.
Where to collect
It is legal to collect plants only with the permission of the owner of the property on which they are found. Government agencies that manage land generally grant permits only to researchers working for an approved institution, such as a university. Private landowners are often willing to allow judicious collecting if asked. Do not collect illegally.
What to collect
If the plant is small, take the whole thing, roots and all, or even several of them. If large, get a branch about 10 inches long, with leaves, flowers, and fruits, if possible. A "sterile" specimen (one with leaves only) may be impossible to identify. Even an old empty seed capsule can be helpful if that's all you can find.
The date the plant was collected and the location as exactly as possible. Record anything that the specimen won't show, for example, the size of the plant, flower color, whether the plant is woody or not, etc. Note what kind of a place the plant was found, e.g., in gravel at stream edge, in shade under live oaks, in sidewalk crack outside Walmart. If you bring your plant to the museum for identification, we might want to keep it for the herbarium. If so, we will need all the information you can give for the label. If you will be preparing your own labels for us, they must be printed on acid-free bond paper.
How to press a plant
Place the specimen in a folded newspaper sheet. Write the date and collection locality on the newspaper. Arrange the plant so that all parts show, for example, don't get the flowers between layers of leaves. Separate the specimens with corrugated cardboard for air circulation (and blotters or paper towels to absorb moisture, if you like). Place the stack between boards and strap them tightly or place a heavy weight on top. Put the stack where there is good air circulation--it is air, not heat, that dries plants. Don't cook them.
Examine the plants daily and change blotters as needed. Remove plants from the stack when they are dry (stiff and no longer cool to the touch). You can kill insects in dried plant specimens by freezing them for three or four days, and keep them pest-free in a tightly-sealed plastic bag.