How to Store and Preserve Plant Specimens Collected in the Field

Collecting plant specimens in the field is a fundamental practice for botanists, ecologists, conservationists, and hobbyists alike. Proper storage and preservation of these specimens are crucial to ensure their longevity and usefulness for research, education, or herbarium collections. This article explores the best practices for storing and preserving plant specimens collected in the field, covering preparation techniques, drying methods, packaging, labeling, and long-term storage considerations.

The Importance of Proper Preservation

Plant specimens provide valuable information about biodiversity, plant taxonomy, ecology, and environmental changes over time. Improper handling or storage can lead to decay, mold growth, insect damage, or fading of important morphological features. Preserving specimens correctly maintains their scientific integrity and usability for decades or even centuries.

Preparing Plant Specimens in the Field

Collecting the Right Material

When collecting plant specimens, it is essential to gather parts that best represent the species. This typically includes:

Leaves: Essential for identification but should be healthy and undamaged.
Flowers or Fruits: Necessary for reproductive features that aid in accurate identification.
Roots or Stems: Provide additional structural characteristics; roots should be collected carefully to avoid damage.
Whole Plants: For small plants like herbs or seedlings.

Avoid collecting diseased or heavily damaged plants as these may not preserve well.

Ethical Considerations and Legal Permissions

Before collecting, ensure you have the necessary permits or permissions from landowners or relevant authorities. Avoid over-harvesting from rare or endangered populations to minimize ecological impact. Collect only what is necessary for study.

Initial Handling and Documentation

Immediately after collection:

Place specimens between sheets of newspaper or clean paper to prevent wilting.
Avoid stacking wet specimens together as this promotes mold growth.
Record detailed field notes including location (GPS coordinates if possible), date, habitat description, collector’s name, and any notable observations about the plant’s environment or condition.

Drying Plant Specimens

Drying is a critical step that halts decomposition by removing moisture from tissues. The goal is to dry specimens quickly but gently enough to retain color and structural details.

Pressing Plants

Use a Plant Press: The typical plant press consists of two wooden frames tightened with straps or screws. Place each specimen between sheets of absorbent paper (newspaper works well).
Arrange Specimens Carefully: Spread out leaves and flowers so they do not overlap excessively and key features remain visible.
Include Absorbent Layers: Alternate specimen sheets with blotter paper or cardboard to absorb moisture.
Apply Pressure: Tighten the press firmly but not overly tight to crush delicate parts.
Ventilation: Keep the press in a warm, dry place with good air circulation to speed drying.

Using Alternative Drying Methods

If a traditional plant press is unavailable:

Microwave Drying: Can be used for small specimens on low power settings with blotting paper; proceed cautiously to avoid burning.
Silica Gel: For succulent or fleshy plants that do not dry well with pressing; bury small parts in silica gel crystals to absorb moisture.
Field Dryers: Portable electric dryers can accelerate drying under controlled temperature and humidity.

Duration of Drying

Drying time varies depending on plant thickness and environmental conditions but typically ranges from 2 days to 2 weeks. Regularly check specimens every 24 hours and change blotter papers if damp.

Mounting and Labeling Dried Specimens

After drying, mounting the specimens on archival-quality herbarium sheets enhances their preservation and ease of handling.

Mounting Techniques

Use acid-free paper measuring approximately 11.5 x 16.5 inches (standard herbarium size).
Attach specimens using one or more of the following:
White glue (e.g., PVA glue) sparingly applied.
Strips of archival tape or linen tape wrapped around stems or leaves.
Sewing with fine thread through thicker stems for added security.

Avoid excessive glue that can darken over time or damage the specimen.

Creating Labels

Each mounted specimen should include a label with:

Scientific name (genus and species)
Common name(s)
Collection date
Geographic location (detailed locality + GPS coordinates)
Habitat description
Collector’s name and collection number
Notes on phenology (flowering/fruiting stage), abundance, associated species

Labels should be printed or handwritten in archival ink on acid-free paper and securely affixed to the sheet’s lower right corner.

Packaging and Transporting Specimens

If immediate mounting is not possible in the field:

Keep dried specimens between clean sheets of paper.
Store them flat in rigid folders or cardboard boxes to prevent bending.
Avoid exposure to moisture during transport—use waterproof covers if necessary.
Keep insect repellents like naphthalene balls away from specimens as they may cause chemical damage; instead consider safe insect-proof storage solutions after arrival at base facilities.

Long-Term Storage of Plant Specimens

Proper long-term storage preserves plant specimens for future reference and study.

Environmental Conditions

Maintain consistent environmental parameters:

Temperature: Ideally between 15–21 °C (59–70 °F).
Humidity: Low humidity around 30–40% RH helps prevent mold growth.
Light Exposure: Store in dark conditions away from direct sunlight to preserve color and prevent fading.

Herbarium cabinets are designed for these conditions with sealed doors and sometimes climate control.

Pest Management

Insects such as beetles, moths, and silverfish can severely damage dried plants.

Periodically inspect collections for signs of infestation.
Use freezing techniques—freeze new collections at -20 °C (-4 °F) for a few days to kill insects before integrating into main collections.
Employ integrated pest management strategies including traps and monitoring rather than chemical pesticides which may harm specimens.

Handling Practices

Always handle mounted specimens carefully:

Support entire sheet when moving—avoid flexing which can cause brittle fragments to break off.
Use clean hands or gloves to prevent oils from transferring onto specimens.

Digitization through high-resolution scanning also reduces physical handling needs while making data widely accessible.

Special Considerations for Different Plant Types

Some plants require tailored preservation methods:

Succulents and Fleshy Plants

Difficult to dry flat without distortion; often better preserved by:

Air-drying without pressing, then storing in sealed containers with silica gel.
Photographing fresh appearance before drying due to color loss.

Mosses, Liverworts, and Lichens

Collected on small substrates like bark; dried slowly without pressing too hard to maintain texture.

Woody Plants

Leaves alone may be collected; woody stems require longer drying times due to higher moisture content—sometimes split longitudinally before pressing.

Conclusion

Storing and preserving plant specimens collected in the field is a meticulous process that demands attention from initial collection through long-term curation. By following proper techniques—including ethical collection practices, effective drying methods, secure mounting with accurate labeling, careful packaging during transport, controlled environmental storage conditions, and pest management—plant specimens can remain valuable scientific resources indefinitely. Whether for academic research, conservation efforts, or personal study collections, investing time in proper preservation ensures that these botanical treasures continue contributing knowledge across generations.