Fig. 1

The spatial distribution and characteristics of the two types of torreya trees in the ancient torreya population. a Spatial distribution of grafted torreya (GT) and non-grafted torreya (NGT trees). The panel on the left indicates the locations of the six sites (A, B, C, D, E, and F) in the ancient torreya tree system. The panel on the right indicates the distribution of torreya trees in the seven to eight plots at each site; blue, red, and green dots indicate individual GT, NGT male, and NGT female trees, respectively, and the dot size indicates the age group (see Additional file 1: Table S1). Tree age ranged from 100–400, 400–700, 700–1000, and 1000–1300 years in group I, II, II, and IV, respectively. b The abundance of GT and NGT trees, and the ratio of female to male NGT trees. Values are mean ± SE. c The percentage of GT and NGT trees in each age group. d Flowering period of GT and NGT-trees. Blue, green, and red lines along the X axis indicate the duration of flowering, and bars indicate the percentage of GT trees, NGT female trees, and NGT male trees with 30 to 100% of flowers open. The insert indicates the average number of flowering days (from initial flowering to flowering completed) of individual GT, NGT female, and NGT male trees; the insert also indicates duration of flowering per plot (from the date when the first tree in a plot began to flower to the date when the last tree in the same plot completed flowering) for GT, NGT female, and NGT male trees. Values are mean ± SE. GT grafted torreya, NGT non-grafted torreya