Illustration by Daniels & Daniels HOMEMADE PRESS drives water out of plant tissue, preserving the specimens. The cuttings should be layered between paper towels and corrugated cardboard.

The museum of natural history nearest you probably harbors an impressive collection of local plant life. Across the U.S., these archives provide an excellent physical record that current and future biologists can use to track how native plants have fared in response to natural and human forces. Historically, amateurs have played a key role in shaping the botanical record, most notably since the Northwest expedition of Meriwether Lewis and William Clark, who preserved and returned hundreds of plants that were then unknown to science. Today each new summer brings an army of botanical enthusiasts scouring the countryside, searching for fascinating flora.

To aid budding botanists, I thought I'd share some museum tips for specimen preservation. You can use these techniques to help add to the official record or simply to engage your family in a rewarding outdoor adventure. Just don't run afoul of the law. Whether on private or public land, collect only if you have permission to do so from the authority responsible for the property. Specimen preservation begins in the field. I suggest photographing each plant before cutting it to keep a record of it in its natural setting. Also, mark on photocopies of a topographical map the exact locations of your finds. Paste these sheets into your field notebook. If the plant is under 15 centimeters (six inches) tall, collect the entire thing, roots and all. Otherwise, cut off a representative part, including flowers, fruits and any seed pods, which can often identify a plant better than its leaves. Tag each specimen with a small paper tab and record in your notebook the species' common name and scientific name if you know it, the date, and any details that a future botanist may need to know. Until you have finished your day's collecting, keep your cuttings hung upside down in the shade to minimize any crimping of their stalks as moisture begins to evaporate from their tissues.

Because cut plants deteriorate quickly, process them as soon as you get home. Begin by dipping each specimen in warm and slightly sudsy water, followed by gentle agitation in clean water to remove the soap. This process will kill bacteria and dislodge tiny crawlers. Thoroughly dry the foliage by blotting it with a paper towel.

Illustration by Daniels & Daniels C-CLAMPS help to secure the setup.

Plants are best preserved by pressing and drying them. Begin by placing three layers of paper towels on top of a stiff board that measures about 30 by 45 centimeters (12 by 18 inches). Then gingerly lay out your cleaned plant, making sure to display different views (front and back) of its leaves. Large flowers should be split with a sharp knife and opened flat with their internal parts face up. Place three more layers of paper towels on top, followed by a sheet of corrugated cardboard and three additional layers of paper towels. Then lay out your next specimen. You can stack up to 10 cuttings this way.

Place a second stiff board on top of the stack and apply steady, firm but gentle pressure to drive water out of the plant tissue and into the absorbent paper. Use a weight or four large C-clamps positioned near the corners. Or if you prefer, you can buy a professional press from a biological supply house. One of the largest is BioQuip in Gardena, Calif. (310-324-0620; product no. 3115; $40). Or check out Fisher Science Education in Burr Ridge, Ill. (800-955-1177; product no. CQS17670;

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