Magnitudinal Asymmetries in Seed Production in Vaccinium corymbosum: Anomaly or Not?

Analyses of the annual seed set taken from 208 shrubs of Vaccinium corymbosum at six locations in eastern North American from 1978 to 1999, showed that at each location, a group of individual plants retained the same rank among the others in the number of viable seeds produced per berry from year to year, and that the top five percent producers in the group produced approximately 25% of the total seed production, while on the low end a group of about half the plants contributed < 10% of the total. The relationship between the cumulative proportions of seed set per plant against the cumulative proportion of producers is consistent throughout the six locations, with some evidence of clustering of locations. At all locations, the proportion of seeds produced per plant or equivalently the total seed production per plant over the sampling period has right skewed distributions. At each location, the same proportion of plants produces the same proportion of seeds. The total number of seeds produced at each location are closely fitted by Weibull distributions with shape parameters less than 1, indicating that the more seeds a given plant has produced the more likely it will produce in the future.