Variation and allometry of seed weight in Aeschynomene americana

One hundred and fifty seeds from each of 72 Aeschynomene americana populations with world-wide origin were weighed individually and the mean and distribution of seed weight were calculated and compared between populations. Mean seed weight varied less than five-fold between populations with about 80% having a mean seed weight between 2-3 mg. However, differences between the largest and smallest seeds (2-8 mg) ranged two-17-fold within populations. Populations that had larger mean seed weights also had larger maximum and minimum seed weights but not larger standard deviations than those with smaller mean seed weights. Seed distributions for populations with a mean seed weight less than or equal to 2 mg were positively skewed while those for all populations with a mean seed weight greater than or equal to 4 mg were negatively skewed. Populations that flowered later produced smaller seeds than those that flowered earlier. (C) 1998 Annals of Botany Company.