Abstract
This study was carried out in the western part of metropolitan Tokyo in an attempt to prevent the local extinction of Cephalanthera erecta (Thunb.) Blume. Seven quadrats (1×1m to 1×7m in size) were established around C. erecta populations under the forest canopy from April 2006 to January 2008. Plant height, the number of leaves and flowers, and the length and width of each leaf were measured. In mid-June 2007, 23 of 194 individuals were dug up, their roots were cut into 2-cm pieces, and cross-sections were examined. The percentage of cells infested with mycorrhiza in each root section was determined. The percentage of cells infected with mycorrhiza clearly increased from basal to apical and in branching roots. Significant positive correlations were found between the amount of infecting mycorrhiza and the numbers of leaves and flowers, leaf area, and drymatter production of C. erecta. It is thought that greater mycorrhiza infection may increase the biomass of C. erecta. Therefore, in situ conservation of the population of C. erecta that is associated with mycorrhizal fungi is quite important.
