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Conserving Threatened Plants

CREW scientists in the Plant Research Division work to conserve threatened plant species that cannot be conserved through conventional seed banking methods—known as exceptional plants.  To do this, we focus on developing protocols for banking threatened exceptional plants using plant tissue culture (in vitro technologies) and cryopreservation.  Our goals are:

  • To develop protocols for growing threatened species in tissue culture and for cryopreserving them, so that genetically diverse collections of these threatened plants can be banked in CREW’s CryoBioBank, as insurance against future extinction.
  • To use tissue culture methods to propagate threatened plants to support their restoration in the wild
  • To facilitate conservation of exceptional plants through the training of students, interns, and young scientists, and globally through the Exceptional Plant Conservation Network

When seeds are banked, they first must be dried to a very low moisture level (something most seeds are adapted to doing in nature), and then the dried seeds are put into a freezer and kept at -20oC (-4oF), where they will last for many years.  An example of large seed banks of wild plant species is the Millennium Seed Bank Partnership in England, the European Native Seed Conservation Network (ENSCONET), the collaboration of the Center for Plant Conservation in the United States with the National Laboratory for Genetic Resource Preservation (USDA), the National Seed Bank Partnership in Australia, and the Germplasm Bank of Wild Species in China.

Threatened Exceptional Plants
The CREW Plant Division focuses on Threatened Exceptional Plants (TEPs) or those threatened plant species for which seed banking is not an option for long-term ex-situ conservation. Ex-situ conservation is the conservation of plants away from their native habitats. It includes growing plants in places like botanical gardens as living collections or conserving the species as seeds in a seed bank. Seed banking is a very effective and efficient method for preserving plant genetic diversity for long periods of time in a small space. However, not all species are adapted to the methods required for current conventional seed banking.
Exceptional Species
Exceptional species, however, are plants that will not survive the conditions of seed banking, are short-lived in seed banks, or they have no seeds available to the bank.  Fortunately, there are other methods that can be used to preserve exceptional species, including cryobiotechnologywhich combines the methods of cryopreservation with in vitro biotechnologies.  These methods are used in the CREW Plant Division to propagate TEPs and store them long-term at -196oC (-321oF) in liquid nitrogen in CREW’s CryoBioBank.

Crew Plant Lab

To learn more about some of the species the CREW Plant Lab is working, expand one of links below.


The Local Flora Project’s goal is to understand how changes in our region over the past 200 years have affected local flora.

CryoBioBank® is a cryostorage facility for long-term germplasm storage of seeds and tissues of threatened plants.