Dryas octopetala var. asiatica, a glacial relict plant species, is now fragmentally distributed in wind-blown fellfields in middle-latitude mountains in northeastern Asia. Because of the specific habitat requirements of this species, its isolated distribution, and therefore restricted gene flow between populations, there is concern that the population will decline with global warming. To assess the reproductive viability of D. octopetala var. asiatica growing in a southernmost population in its

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... geographical distribution in the Tateyama Range of central Japan, we examined the maturity and germinability of seeds under various thermal conditions in laboratory experiments. We compared the viability and germination behavior of the seeds of this relict species with those of a snowbed alpine species, Sieversia pentapetala, commonly distributed in alpine regions in Japan. The seeds of D. octopetala var. asiatica showed lower maturity and greater susceptibility of seed germination, i.e., fewer seeds germinated in the warmest thermal condition (35•Ž) in D. octopetala var. asiatica than in S. pentapetala.