The ability of seed of native Western Australian species to be stored
using cryopreservation methods was investigated by subjecting seed of
90 native species representing 84 genera and 33 families to storage in
liquid nitrogen. Seed of 68 native Western Australian species were ge
rminated after storage in liquid nitrogen for two weeks following trea
tments which involved direct plunging into liquid nitrogen or slow coo
ling at 0.4-degrees-C min-1 in 15% dimethyl sulphoxide (DMSO) or slow
cooling at 0.4-degrees-C min-1 in 35% DMSO. The largest number of spec
ies (37) responded positively to direct plunging without pretreatments
, with only 10 species responding to slow cooling in 15% DMSO. Thirty
one species had enhanced germination and 10 species depressed germinat
ion after any of the liquid nitrogen treatments. There were no trends
in a species ability to survive liquid nitrogen storage and freezing r
egime, moisture content, seed size or taxonomic relatedness. However,
hard seeded species belonging to the families Caesalpinaceae and Papil
ionaceae showed a consistently high degree of tolerance to liquid nitr
ogen storage. Significant physical damage to seed and cotyledons only
occurred in Templetonia retusa (Papilionaecae) and this was alleviated
by nicking the seed coat. This study indicates that seed of a large p
roportion of native Western Australian species may be amenable to stor
age in liquid nitrogen and that at least 40% of the listed rare and en
dangered species of Western Australia could be maintained in this way.