The seeds from the other 10 species were similarly sh lived
in the ageing experiment with a mean P50 value of 21.3 d
(S.E. 2.10; Table 1). All these seed-lots were aged under the
same conditions, 60% RH at 45 8C, as a larger comparative
longevity screen currently being conducted—a study which
contributes to the Millennium Seed Bank Project. The mean P50
value for more than 150 species included in the screen to date is
75 d