Seed dormancy of northern landscaping plants requiring two winters from seed dispersal to shoot emergence above ground.

通过室内和室外试验，揭示了日本北部极具应用前景的园林绿化树种--金鸡儿和菊花种子的萌发特性。两种植物的种子均于10月在室外散播，种子在次年6、7月出根，播种两年后的5月出芽。这意味着种子从种子散布到出苗需要大约20个月，其中包括两个冬天。种子散布后立即发育的胚胎体积较小，与种子从胚乳中吸收营养的吸器出根几乎是一致的。在两种种子中，低温层积提高了胚根出苗率，但温度和光照的交替抑制了胚根出苗率。

We revealed the germination characteristics of seeds of Convallaria keiskei and Maianthemum dilatatum, which are promising species as landscape materials in northern Japan, by laboratory and outdoor experiments. In both species, seeds were dispersed in October outdoors, roots emerged from seeds in next June or July, and shoot emerged in May two years later of seed dispersal. This means seeds require about 20 months including two winter from seed dispersal to shoot emergence. Embryos in seeds immediately after dispersal were small and developed at the almost coincidentally with root emergence from seeds functioning as haustorium absorbing nutrition from endosperm. In both seeds, percentages of radicle emergence increased by cold stratification but alternating temperatures and light inhibit them.