Fig. 5. Spring (April to May) and summer–fall (June–October) yield vs. species number sown for one site in Pennsylvania and two sites in Ohio. Open symbols are treatments unique to that site and closed symbols are treatments common to all three sites, dotted lines connect the mean for each number of species and solid lines are the regression for those means, vertical bars show mean standard error for each species treatment, symbols are means of three or four replicates. Data are revised from Barker et al. (2003).