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Plant Material Collection Guide

Plant Material Collection Guide

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Role of Plant Materials Centers and Conservation

The NRCS Plant Materials Program selects conservation plants and develops innovative planting technology to solve the nation's most important resource concerns. Just as with most things in nature no two plants are alike, meaning that plants vary among species. This variability influences the adaptability of a plant to different environments.
Plant Materials Centers (PMC) evaluate this variability among plant species and select plants that will perform the best in the environment of concern. For over 70 years, Plant Materials Centers and Specialists have provided essential and effective plant solutions for critical habitats, environmental concerns, management practices, and key farm and ranch programs. The Plant Releases and technology developed at PMC's are incorporated into the NRCS Field Office Technical Guide (FOTG) and become standards for conservation practices implemented on public and private lands. Over 70 percent of the plant species listed in the FOTG were selected by the Plant Materials Program.

Why Perform Plant Collections?

This is your opportunity to provide a dramatic conservation impact. NRCS Plant Materials Centers have identified several key species to address resource concerns in Texas, Oklahoma and Louisiana; we need your help. To help identify these plants the PMC's rely on NRCS Field Office Conservationist, private landowners and other state and federal agencies in the field. You have expert knowledge of plant communities in your area and can perform field collections for the Plant Materials Program. Who knows, perhaps the plants you collect will become the next vegetative conservation solution for your area and beyond!

What to Collect?

NRCS sends out a bulletin every year which lists the high-priority species. A detailed description of each species and photographs are available on the Texas NRCS website under Plants Collection. It is important to become familiar with the list prior to field season so that collection opportunities are maximized. Wildflower populations must be identified during flowering because it is difficult to locate the plants after the colorful blossoms have gone to seed. Know what to look for and mark the site for later visitation to collect seed. A GPS unit is a valuable source to reliably record accurate site locations.

Where to Collect?

Never collect seed from a yard, lawn, garden, park, or any other obviously cultivated site! Seed should be collected only in a wildland setting. It is important to obtain a complete genetic representation, so sample from many plants, not just a single plant. Plant populations growing in unusually harsh conditions are very good candidates for collection. Collect as much seed as possible over an entire area that is environmentally similar in associated plant community composition, soil type, aspect, and elevation. This means, for example, the same habitat type, ecological site, etc. Most of the high-priority species have a very large geographic distribution, so it will be necessary to conduct several collections across all the counties within a natural resource area. Always obtain prior permission from the landowner to collect seed.

When to Collect?

Collecting seeds at the correct time is crucial for propagation to be successful. The best time to collect seed is when the largest amount of seed is ripe or filled. The actual time of flowering and fruiting will vary from year to year, with precipitation and temperature as the driving factors. In general the interval between bloom and seed maturity is about 4 weeks. Cool moist weather may lengthen the interval while hot dry weather may shorten it. It is necessary to periodically monitor plants for seed maturity. Seed is usually ready to harvest when it feels firm. Hand cut a cross-section in a few representative seeds to determine stage of maturity. Figure 1 illustrates the difference between immature seed in a soft dough stage, as compared to mature seed in a hard stage. Seed in the firm dough stage will continue to mature into viable seed. The trick is to avoid collecting seed that is green, or immature, but also to harvest prior to shatter and dispersal. For more information refer to 'Determining Seed Fill in Grasses' brochure developed by the Knox City Plant Materials Center.

Determining Seed Fill in Grasses  (PDF; 660 KB)

Figure 1
Seed fill - soft dough stage and hard stage Immature, soft dough stage on the left, and mature, hard stage on the right; note the green seed fill of the seed on the left.

How to Collect

A physical examination of the seed is crucial, take time to visually inspect for signs of immaturity.


  • There should not be any remaining sign of flowering parts, such as anthers, stamens, or petals on the plant. Try to collect seed during dry weather because excess moisture is fatal to seed viability.
  • Remove a small portion of the inflorescence and rub vigorously in the palm of the hand to loosen the seed from the stalks. It may be necessary to use a hand lens or other eye aid to get a close enough look to identify the seed.
  • Carefully sort through the chaff for seeds and check readiness by clipping with a fingernail clipper or cutting with a knife.
  • The seed is ready to harvest when the endosperm is firm. No moisture should be present when the seed is cut or rubbed in the palm of the hand. Mature seed ranges in color from tan to dark brown, and rarely is green. It will be necessary to check several plants in the immediate area, as ripening will vary among individuals. Waiting a few days may result in a more fully mature seed crop.
  • Native legumes are very often attacked by seed predators. Carefully cut open a few seed and inspect for the presence of live larvae. Make sure there is not just an empty shell left behind after the insect consumed and vacated the seed. Another clue is the presence of a minute entrance hole where the insect accessed and vacated through the seed coat.
  • Use a sharp utensil, such as scissors, knife, or clippers to remove the inflorescence and a small amount of stalk. In many instances where the size of the area and number of plants is moderate, it is just as easy to hand-strip. It is best to harvest only the inflorescence or seed structure, as unnecessary vegetation such as leaves and stems, add undesirable moisture and bulk. In the case of indeterminate flowering (different stages occurring on a plant at the same time), a greater amount of material should be harvested to allow more seed to mature.
  • Gloves may be needed for handling the sharp or thorny capsules and pods of some species.
  • Collect as much seed as possible, while only taking approximately 20 percent of the total seed crop in a given area.
  • At this time of the year, many of the plants will be very dry and brown in appearance. If possible, choose only to harvest from healthy, robust plants.
  • Carefully place material in paper sacks with adequate room for air circulation to promote drying.
  • Do not store seed for any length of time in plastic sacks! Plastic holds moisture and increases temperature and humidity, which very quickly promotes mold and damages the seed.
  • Label each sack with the species, collector's name, and the date.
  • Complete in full.

NRCS-ECS-580: Plant Collection Information (PDF; 64 MB)

Record a description of all physical characteristics, such as elevation, aspect, slope, soil texture, annual precipitation, MLRA, associated species, and ecological condition. Accurately record site location with the use of both a GPS unit and a topographical map to document the township, range, and section, and the proximity of landmarks, such as geographic formations, roads, rivers, bridges, structures, land ownership, etc. This is important because it may be necessary to re-visit the site sometime in the future.

After transporting, leave the sack open and periodically stir up the contents to promote drying. It is best if material can be spread out on a flat surface to dry at room temperature. When curing is complete, temporarily store the bag in a place that is cool and dry until it can be sent to the Plant Materials Center requesting the collection.

Where to Send?

Mail or deliver seed collections to the following address:

James E. "Bud" Smith Plant Materials Center
3776 FM 1292
Knox City, TX 79529-2514

East Texas Plant Materials Center
6598 FM 2782
Nacogdoches, TX 75964

Kika de la Garza Plant Materials Center
3409 N FM 1355
Kingsville, TX 78363

The PMC processes the material to clean seed, assigns an accession number to each viable collection, and periodically installs initial evaluation plantings to test the performance of individual collections against one another. Assigned accession numbers are sent to the original seed collector(s) so they also can track the reported performance of the material throughout the testing and selection process. Superior performing material will proceed to comparative evaluation plantings, seed increase, field evaluation plantings, and eventual selection and release for distribution to the commercial seed industry.

How Does this Help?

The NRCS Field Offices play a vital role in the continued testing and selection of native species that help to conserve and protect the natural environment. The PMC's plant releases will, with the assistance of the Field Offices and others who collect seed, continue to grow and be beneficial in biomass production, carbon sequestration, erosion reduction, wetland restoration, water quality improvement, streambank and riparian area protection, and other special conservation treatment needs.

Need More Details?

Additional information can be found in the following references:

Plant Materials Collection Guide, USDA NRCS Boise, Idaho, Technical Note Plant Materials No. 1, December 2003.
Collecting Plant Material, USDA NRCS Brooksville, Florida, Technical Note No. 35, 1997.
Collecting, Processing, and Germinating Seeds of Wildland Plants, J.A. Young and C.G. Young, Timber Press, October 1986.

If you have any questions, please contact one of the following:

Rob Ziehr, Plant Materials Specialist
Phone: (254) 742-9888