Floral Characteristics and Breeding Systems of an Endangered Species Cypripedium japonicum | 濒危植物扇脉杓兰的花部特征与繁育系统

Chinese. 通过野外观测,运用杂交指数（OCI）,花粉萌发试验,去雄、套袋、人工授粉等方法对扇脉杓兰开花特性、花粉活力、柱头可授性、繁育系统进行研究,并对其柱头表面和花粉进行扫描电镜观察。结果表明：扇脉杓兰4―6月份开花,群体花期23天,单花花期12～16天。开花当天柱头即具有可授性,柱头可授性持续期为14天左右。花粉活力在花朵刚开放时最高（95%）,至花朵凋谢之前仍保持较高的活力（70%）。雌雄生殖单位在持续时间上有较长的相遇期。开花时柱头略高出花药,在花朵开放的整个过程中雌、雄蕊的相对位置始终不变。扇脉杓兰杂交指数OCI=4。自然条件下,扇脉杓兰的结实率仅为5%。人工自花授粉、异花授粉的结实率分别为90%和95%,表明扇脉杓兰是高度自交亲和的。而套袋后不采取措施和去雄的花均不结实,表明扇脉杓兰不存在自动的自花授粉、无融合生殖,因而扇脉杓兰必须通过一定的媒介传粉才能繁衍后代。

English. Cypripediumjaponicum, a perennial herb of Orchidaceae, with unique flower shape, brilliant flower color, ornamental and medicinal value. Due to over-harvesting and the environment changes,a large number of wild populations of C. japonicum reduced, and some genetic resources lost. The species is in endangered, and listed as a national endangered plant. Consequently, it is essential to execute studies on floral characteristics and breeding systems of C. japonicum for understanding its extinct mechanism. We conducted a field investigation, and experiments of pollen germination test, emasculation, bagging and artificial pollination, and applied out-crossing index, to study the flowering character, pollen viability, stigma receptivity, breeding system of C. japonicum in natural populations. We also observed surface pattern of pollen and stigma by using an electron microscope. Results showed that： C. japonicum bloomed from April to June and the flowering span was 23 days among populations. The life span of one single flower was approximately 12 - 16 days. The stigma receptivity started from bloom and lasted for 14 days, and the pollen viability was high in the whole florescence. The stigma exceeded stamen in position and the relative difference in position between the stamen and style remained unchanged in the whole flowering process. The total value of OCI was 4. Seed setting propagation coefficient of C. japonicum was low under field conditions, with only 5%. Based on the results of emasculation, bagging and artificial pollination experiments, C. japonicum is self-compatible and can＇ t self-pollinate autokineticly and has no syngamy. Thus, the breeding system is pollinators depended.