Seed germination and dispersal strategy of Trillium apetalon (Trilliaceae): a typical temperate woodland perennial in Japan

Seed dispersal and germination mechanisms of Trillium apetalon Makino were investigated in field populations and under experimental conditions. Seeds mature in mid‐June in lowland populations, and in late July to early August in montane to subalpine populations. In the field, seed dispersal and germination proceed in distinct phases. Mature seeds, each with a large soft seed elaiosome, are dispersed by ants. Following dispersal, the radicle elongates first, but the cotyledon is still covered with the seed coat. The first true leaf (plumule) develops, and then the cotylendon (d) disappears. Subsequently, the first radicle (b) disappears, but a single new root (bl) is formed, with an old radicle trace (f). Finally, the first radicle disappears completely and then a single root is formed. Approximately 70% of all seeds produced germinated in the field. Approximately half germinated in the autumn following dispersal and approximately 20% of the remaining seeds germinated in early summer, but a few remaining seeds germinated in late summer of the succeeding year, more than a year and half after seed dispersal. Light conditions did not affect germination, but seeds lost their viability under dry storage conditions. In the field, litter cover may be important because it moderates temperature and retains moisture. The hydrocarbons contained in the seed elaiosome obviously play a role, attracting ants for seed dispersal.