Researching the Aging and Longevity of Rare Plant Seeds

Astragalus bibullatus in Fruit. Attempts to establish a new population of A. bibullatus began in 2001.

How Long Do Rare Seeds Live in Frozen Storage?

High rates of plant extinction have led botanical gardens to use seed banking as a cost effective conservation strategy. Thus, the CPC National Collection is maintained primarily as seeds that are stored in “orthodox” storage at -18 C in the freezers of botanical gardens. CPC’s seed banks aim to keep seeds alive for decades or centuries as safeguards against the loss of wild populations. Because most research has been conducted on crop species, no one actually knows how long many rare plant seeds can survive in seed banks.

To ensure better stewardship of rare plants, CPC’s national office, its network of botanic gardens, and the National Laboratory for Genetic Resource Preservation (NLGRP) were recently award an Institute for Museum and Library Services National Leadership Grant (MG-245983-OMS-20) to test aging and longevity in wild rare plant species seeds in a new way. Recent research with crop species shows that biochemical indicators can reliably measure seed aging and predict seed longevity. RNA integrity number (RIN) has shown particular promise as a metric of seed aging. Applying this new technology to wild species will be especially useful for curators, given the enormous variation wild seeds display in germination requirements and storage behavior.


Abies fraseri
Abronia umbellata ssp. brevifolia
Agalinis skinneriana
Aletes humilis
Amaranthus pumilus
Amelanchier nantucketensis
Amorpha herbacea var. crenulata
Amsonia tharpii
Anemone patens var. multifida
Arctostaphylos catalinae
Aster furcatus (Eurybia furcata)
Astragalus albens
Astragalus bibullatus
Astragalus cremnophylax var. hevronii
Astragalus hypoxylus
Astragalus linifolius
Astragalus magdalenae var. peirsonii
Astragalus tegetarioides
Berberis nevinii
Besseya bullii
Bidens torta
Boechera parishii
Bonamia ovalifolia
Calochortus umpquaensis
Campanula scabrella
Carex comosa
Carex oronensis
Castela emoryi
Castilleja kaibabensis
Castilleja levisecta
Ceanothus cyaneus
Ceanothus roderickii
Charpentiera elliptica
Chrysopsis floridana
Cimicifuga elata
Cirsium pitcheri
Clarkia biloba ssp. australis
Clarkia lewisii
Clematis socialis
Clermontia kakeana
Cordylanthus maritimus ssp. palustris
Cyanea angustifolia
Dalea foliosa
Deinandra increscens ssp. villosa
Deinandra mohavensis
Dicerandra immaculata
Dodonaea viscosa
Dubautia menziesii
Echinacea tennesseensis
Echinocactus horizonthalonius var. nicholii
Eragrostis variabilis
Erigeron parishii
Eriogonum crosbyae
Eutrema penlandii
Festuca ligulata
Geum geniculatum
Gilia leptantha ssp. leptantha
Hedeoma diffusum
Hesperocyparis abramsiana
Hesperocyparis forbesii
Hibiscus dasycalyx
Horkelia hendersonii
Hymenoxys texana
Kalmiopsis fragrans
Lasthenia burkei
Leiophyllum buxifolium
Liatris novae-angliae
Lilium parryi
Linum carteri var. carteri
Lomatium bradshawii
Lupinus westianus var. aridorum
Lycium sandwicense
Malacothamnus clementinus
Metrosideros polymorpha var. polymorpha
Nolina brittoniana
Orcuttia californica
Osteomeles anthyllidifolia
Oxypolis canbyi
Oxytropis campestris var. chartacea
Packera franciscana
Paysonia stonensis
Penstemon clutei
Penstemon peckii
Penstemon shastensis
Phacelia formosula
Physaria globosa
Physaria obcordata
Pityopsis ruthii
Plagiobothrys hirtus
Poa mannii
Pogogyne nudiuscula
Polemonium eddyense
Polemonium occidentale ssp. lacustre
Polyscias racemosa
Ptilimnium nodosum
Purshia subintegra
Remirea maritima
Remya kauaiensis
Rhus kearneyi ssp. kearneyi
Sarracenia oreophila
Schoenoplectus tabernaemontani
Senecio ertterae
Sesbania tomentosa
Sidalcea nelsoniana
Solidago plumosa
Tephrosia angustissima var. corallicola
Thermopsis macrophylla
Tumamoca macdougalii
Vaccinium boreale
Vaccinium crassifolium ssp. sempervirens
Warea amplexifolia
Ziziphus celata

Goal of Study & Accession Definitions

The overarching goal of this study is to compare the germination-based viability and RNA integrity of seeds held in frozen storage for 15+ years to seed recollected or regenerated from the same plant population. We are testing the hypothesis that RNA Integrity or (RIN) can linear proxy of seed health in storage that can be used to inform curation and management decisions surrounding rare plants.   Please see grant project narrative for full details.

For simplicity, hereafter, the seed currently held long term storage will be referred to as the “original accession” and seed that participants re-collect or regenerate is known as the “fresh accession.”

Partner Instructions

Species Target List & Seed Quantities

  • Make one “fresh” seed collection from each target species listed in your contract. Fresh collections should either be made from the same population as the “original accessions”; from ex-situ plants of shared wild provenance; or from plants grown or bulked from seeds of a seed collection held in long term storage for 15 years or more – known as the “original accession.” The specific quantity of seed required for testing may vary depending on the size of seed and inclusion in the different experimental groups. Changes to the list of approved species or accessions recollected in the study must be approved in advance via email correspondence with CPC Contact, Dr. Katie Heineman (

Recollecting & Processing of “Fresh Accession”

  • Participants will obtain permits necessary to collect the “fresh accession”.
  • While acquiring seed for testing is a first priority, collectors should make a good faith attempt to make a full population level conservation collection according to the CPC Best Practice guidelines, meaning, in most cases, that seed not set aside for testing should be collected & stored along maternal lines.
  • Clean, process, and send seeds to NLGRP within 90 days of collection to ensure that “fresh seeds” used in the study are of similar maturity.
  • Send seed intended for testing in the specified quantity in a single bulk packet that integrates over available maternal lines. Participants may send the additional seed for back up storage to NLGRP simultaneously or later in the collecting season if more time is needed to process.
  • All seeds collection should be processed & sent to NLGRP no later than  August 31, 2023 (and no more than 90 days after your most recent seed collection).

Material Transfer of Fresh & Original Accessions to National Laboratory for Genetic Resources Preservation

  • Process and send fresh seeds to NLGRP within 90 days of collection to the address below. We encourage that the “original accession” be sent in advance of the fresh collection if possible, but both should arrive at least concurrently:
    • Chris Walters and Lisa Hill
      1111 South Mason St.
      Fort Collins, CO 80523-0001
  • Email CPC staff ( and Lisa Hill at NLGRP ( prior to sending seed to ensure NLGRP is able to receive your package and to verify that an adequate quantity of seed for testing.
  • Use the online NLGRP submission form on the CPC member resources section of the CPC website to submit data associated with each accession (
  • Send seed intended for testing in a single bulk packet that integrates over available maternal lines. Participants may send the additional seed for back up storage to NLGRP simultaneously or later in the collecting season if more time is needed for processing.
  • Fresh and frozen sent for the first time from a CPC Participating Institution for this study will enter the NLGRP collection under the CPC-NLGRP Material Transfer Research Agreement. Details regarding this agreement can be found here.
    • To release of seed for testing currently held under a Material Transfer Research Agreement at NLGRP (AKA “Research Storage” AKA MTRA), contact Lisa Hill:
    • To release seed for testing currently held under a Material Transfer Agreement at NLGRP (AKA “Blackbox Storage” AKA MTA), contact Stephanie Greene:
  • Seeds should arrive at NLGRP no later than August 31, 2023 (and no more than 90 days after your most recent seed collection).

Reporting & Invoicing

  • Prior to submitting your invoice for collections, collectors must ensure that:
    • Both the “original” and “fresh” test packets have been received by the staff at NLGRP in Fort Collins
    • Data for the fresh recollection has been entered through the NLGRP submission form on the IMLS
    • You have posted one photo and one conservation update per contracted species via the CPC website at 
      • The “conservation update” will consist a one paragraph narrative description of the recollection or seed bulking process or lessons learn through past seed curation of this species.  Any photo of the species biology (flowers, fruits, habitat, field work) would be acceptable.
  • Submit invoice via provided Invoice Template IMLS to no later than September 30, 2023.

Inventory of Seeds Received by NLGRP

Where will the seeds be tested for RNA analysis?
      The CPC National Office is granting the contracts and the lab work will take place at the National Laboratory for Genetic Resources Preservation in Fort Collins, Colorado in the lab of Dr. Chris Walters.
How should I process seed intended for testing prior to sending to NLGRP?
      Please process seeds intended for testing as you would for long term storage. Please clean seeds and dry them to ~30% RH at room temperature. Place seeds intended for testing in a bulked packet and ship overnight to NLGRP within 90 days of collection. You may take additional time to process the full population level seed collection.
How do I pay for shipping to NLGRP?
      There is no grant line or purchase code for shipping. The shipping costs are part of the $2800/collection reimbursement you will receive upon invoicing.
Do I need to track time and expenses? 
      Nope! You just need to provide proof subcontract deliverables as outlined on the Invoice Template IMLS