Fig. 4. Mean out-crossing levels observed at each field sampling location in 1998, 1999, and 2000. Samples were collected at 1.8 m (6 ft), 9.4 m (31 ft), 20.6 m (68 ft), 35.8 m (118 ft), and 200 m (660 ft) from the field edge nearest to the adventitious pollen source. Data are the mean for 60 field transects in 1998, 93 transects in 1999, and 162 transects in 2000. The Y-axis error bars represent the 90% CI. Plotted distances are offset each year for clarity.