A particular challenge for ex situ genebanks is the maintenance of genetic integrity. Contamination with non-self pollen or inadequate handling during multiplication will inevitably downgrade genetic identity. Molecular markers are used at IPK to control this potential problem by maintaining both the seed harvested from the most recent multiplication and a herbarium voucher specimen collected from the initial multiplication. The cereal herbarium collection includes samples of both the grain and intact spikes of each accession. Pilot DNA fingerprinting studies have revealed that in self-pollinating species such as wheat (Triticum), a high degree of identity is preserved, whereas in open pollinating species such as rye (Secale), allele frequencies can shift over time.