The Mexican hot chocolate flower, Cosmos atrosanguineus , is well known in cultivation but is thought to be extinct in the wild.
Stocks grown in the UK come from a very narrow genetic base, possibly from one original plant.
Because of this lack of genetic diversity and the finding that the species is self-incompatible, Tim Wilkinson has been developing cryopreservation as a method for storing the known clone safely, pending the location of others. Tim Wilkinson transferring frozen meristems of Cosmos atrosanguineus into liquid nitrogen. Tim has now succeeded in regenerating plants from tissue stored in liquid nitrogen. Before storage, meristems were encapsulated in alginate and treated with a high concentration of sucrose to protect them from freezing damage. After such treatment, shoots could be regenerated from the meristems by rapid thawing and culture on recovery medium.